Fourth Edition - NCRS
Fourth Edition
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1956-57
Corvette
Technical Information Manual
& Judging Guide
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1956-57 CORVETTETECHNICAL INFORMATION MANUALANDJUDGING GUIDE
Summer 2000 - Fourth Edition
FOREWORD
This manual has been prepared through the assistance of many knowledgeable people whose names are listed below. The information contained herein is based upon research involving published data and inspection of numerous representative vehicles. This manual is intended to serve as a technical information and or judging manual only and not as a vehicle restoration guide. Every effort has been made to publish the most accurate information available at time of printing. Controversial information concerning that which there is not full agreement among knowledgeable people has either been indicated as such or omitted. However, incorrect or incomplete information may appear. Input concerning possible corrections, clarification or additions is encouraged and can be directed to the Team Leader listed below. Please enclose a stamped, self-addressed envelope if you wish a reply.
We wish to express thanks for the many hours of hard work donated by the Team Leader and the team members in assembling this NCRS Technical Information Manual.
|Roy Sinor |Scott Sinclair |
|National Judging Chairman |1956-57 National Team Leader |
|9575 North 177th East Ave. |153 Old King Rd. |
|Owasso, Oklahoma 74055 |Bolton, Ontario, Canada L7E 5R7 |
Revision Team Leader: Scott Sinclair, Bolton, Ontario, Canada
Revision Team Members:
Dave Ewan - New Jersey, Larry Richter – Oregon, Jim Frakes - New York, Dick Robinson – Pennsylvania, Marilyn & Dave Heitzman – Ohio, Gilbert Scrivner –Texas, Mike McCagh – Maryland, Dick Miller - Wisconsin
Manual Editor, Coordination and Quality Control: Vinnie Peters; Patchogue, NY
Except where noted, all material contained in this publication is the exclusive property of the National Corvette Restorers Society, Inc.. No portion of this publication may be reproduced in any way without the express written consent of NCRS. Any reproduction without such consent shall be deemed a violation of federal copyright law. Please direct all written requests to reproduce materials to Roy Sinor, National Judging Chairman, 9575 North 177th East Avenue, Owasso, OK 74055
1956-57 CORVETTETECHNICAL INFORMATION MANUALANDJUDGING GUIDE
PREFACE
NCRS Judging Standard
“Cars are to be judged to the standard of vehicle appearance, and as equipped, at the time and point of final assembly by the Chevrolet Motor Division of General Motors Corporation. Presentation for judging is to be in the condition normally associated with that of a Corvette which has undergone the then-current standard Chevrolet Dealer New Car Preparation for delivery to a purchaser, exclusive of any dealer or purchaser inspired additions, deletions or changes.”
Judging Purpose
The purpose of NCRS Flight Judging will be an effort by volunteer judging teams to determine how closely a vehicle appears to conform to the NCRS Judging Standard, and to recognize such vehicles and their owners with NCRS awards, when earned, that generally reflect the current degree of preservation and/or restoration. In addition, the purpose shall include the judges. transfer of knowledge to the owner on how that owner may wish to further improve their car to more closely match this Standard.
Purpose of this Manual
This manual was developed to provide technical data to evaluate the 1956-57 Corvette against the NCRS Standard. The intent of this manual is to present the Corvette produced as the norm, not the exception. Vehicles having a significant deviation from that norm, as presented here, must be documented by the owner. Any such documentation must be available to the judging team on the judging field in order to receive consideration. The purpose of this manual is not to be a guide to restore Corvettes. However, we recognize that this manual will inevitably be used for that purpose. We have pro-vided some additional information presented as reference material to aid the restorer. Corvettes are low production vehicles built by an assembly line process. As with any assembly line process, minor deviations occur. Some significant changes occurred such as the elimination or introduction of an option or by a running change necessitated by various reasons. We have tried to identify any milestone changes by identifying serial numbers. In most cases, these are approximate and should be viewed as such.
How to use this Manual
The manual is arranged in a manner to facilitate complete and efficient judging. The proper use of this manual will foster consistency in judging and improve our quality. Use this manual in conjunction with the latest edition of the Corvette Judging Reference Manual. Study both manuals and participate in the judging process.
The TEAM
This manual represents the efforts of a team of people. The TEAM has given their time and knowledge to produce this manual. The TEAM has given unselfishly hours of research, examination of vehicles, countless telephone calls, a mile of “fax” paper, hours of proofreading and coordination and computer time to give you this product. The TEAM hopes this manual allows you to enjoy this hobby as much as we do. I would like to thank each TEAM member who, without their support, this product would not be possible.
Fasteners and Finishes
This manual provides information on finishes and fasteners. In most cases, this information is from researching available reference materials and observing original examples. Fasteners are typically provided by several suppliers. This manual states all known headmarks; however, others may exist. The intent is to provide guidance, not to cause owners to change fasteners that are known to be original to their car. We also encourage owners to observe and document the fasteners and finishes on their particular car. We also encourage owners to send us documented data to improve our knowledge. Judges are encouraged to use common sense when using the data on finishes and fasteners provided in the manual and evaluate owner input. Plating finishes are often identified by several names. Cadmium and zinc plating identifies a plated finish that is silver in hue often referred to as “bright cadmium” or “silver cadmium”. Cadmium dichromate identifies a plated finish which has a gold hue often referred to as “gold cadmium” or “yellow cadmium”.
Scott Sinclair 1956-57 National Team Leader
Table of Contents
OPERATIONS SECTION 1
1. Ease of Start 1
2. Choke Function 1
3. Fast Idle Speed 1
4. Exhaust Sound, Leaks, Smoke 1
5. Water, Fuel, Oil Leak 1
6. Slow Idle Speed 1
7. Engine Noise, Vibration, Blow By 1
8. Windshield Washers 2
9. Windshield Wipers 2
10. Horns & Contact 2
11. Park Lights 2
12. Headlights, High & Low Beam 2
13. Front Turn Signals 2
14. Tail Lights 2
15. License Lights 2
16. Rear Turn Signal Lights 2
17. Brake Lights 3
18. Park Brake Function 3
19. High Beam Indicator & Turn Arrows 3
20. Turn Signal Canceling 3
21. Gauge Operation 3
22. Tachometer Operation 3
23. Park Brake Alarm (optional) 3
24. Heater & Defroster (optional) 3
25. Radio 4
STOP ENGINE 4
26. Clock 4
27. Courtesy Lights 4
28. Seat Adjustment 4
29. Neutral Safety Switch or Reverse Lockout 4
30. Ignition Switch 4
31. Cigarette Lighter 4
32. Cowl Vent 5
33. Stowage Compartment Latch & Lock 5
34. Windows 5
35. Doors & Trunk Latching & Locking 5
36. Interior Lights 5
INTERIOR SECTION 6
1. SEATING AREA 6
Seats, Backs and Trim 6
Seat Belts 6
Adjustment Handle and Tracks 6
2. CARPETING 6
Carpet Color 6
Carpet Weave 6
Carpet Binding & Heel Pad 7
Retaining Screws & Dimmer Switch Bezel 7
3. TRANSMISSION SHIFTER ASSEMBLY & CONSOLE AREA 7
Shifter, Boot & Knob 7
Floor Plate & Pattern Plate 7
1957 Ash Tray 8
4. INSTRUMENT PANEL PAD 8
Instrument Pad 8
Sewing & Fit 9
5. INTERIOR MIRROR AND DEFROSTER OUTLETS 9
Interior Mirror 9
Defroster Outlets 9
6. UPPER & LOWER INSTRUMENT PANEL PAINT 10
Upper Panel Color & Gloss 10
Lower Panel Color 10
7. STEERING WHEEL, TURN-SIGNAL SWITCH & MAST ASSEMBLY 10
Steering Wheel & Horn Button 10
Turn Signal Housing & Lever 10
Steering Column Mast 10
8. INSTRUMENTS & CONTROLS 11
Tach, Speedometer, Lighter & Gauges 11
Ignition Switch 11
Controls & Handle 12
9. RADIO, CLOCK, HEATER CONTROLS 12
Radio 12
Speaker/Power Supply 12
Speaker Grille 13
Clock 13
Heater Controls 14
10. PEDALS & AREA UNDER INSTRUMENT PANEL 14
Heater & Defroster Hoses 14
Cowl Vent 14
Insulation 14
Wiring 14
Pedals & Pads 15
11. PARKING BRAKE ALARM, COURTESY LAMP, DOOR SWITCH 15
Parking Brake Alarm & Handle 15
Courtesy Lamp & Door Switch 16
12. DOOR OPENING AREA, DOOR WEATHERSTRIPPING 16
Door Jambs, Hinges & Lock Pilars 16
Door Latches & Strikers 17
Sill Plates 17
Weatherstrips & Cowl Gutters 17
13. DOOR PANELS & COWL KICK PANELS 17
Door Panels 17
Door Panel Metal Moldings & Scuff Plate 18
Kick Panels 18
Arm Rests & Painted Upper Door Trim 18
Interior Door Controls 18
14. DOOR WINDOW REVEAL MOLDINGS & WINDOW POSTS 19
Upper Door Trim & Felts, Seals & Stops 19
Door Window Posts & Liners 19
15. TOP COVER TRIM, SEAT SEPARATOR & PACKAGE COMPARTMENT 19
End Straps 19
Top Cover & Seat Separator Moldings 19
Seat Separator & Package Compartment 19
16. INTERIOR ROOF AREA 19
16A. Interior of Hard Top 19
Headliner 19
Front Latches 20
Side Locator Pin Receivers 20
Interior Header, Moldings & Mounting Brackets 20
Convertible Top Rear Latches (if equipped) 20
16B. Interior of Soft Top 20
Front Latches 20
Rear Latches 20
Bows, Pads & Straps 21
Door Window Weather Seals 21
Front Header 21
Rear Bow Seal 21
17. TRUNK SECTION 21
Trunk Color & Paint Application 21
Weatherstrip 21
Wiring 21
18. HINGES, LATCHES, DIVISION PANEL, SCREWS & CLIPS 22
Hinges 22
Division Panel 23
Screws & Clips 23
19. TRUNK MAT, SPARE COVER & BOLT 23
Trunk Mat 23
Spare Wheel Cover & Bolt 23
Label(s) 24
20. JACK, HANDLE & LUG WRENCH 24
Jack 24
Jack Handle 24
Lug Wrench 25
Stowage Clips 25
21. POWER FOLDING TOP EQUIPMENT 26
22. OVERALL CLEANLINESS 26
EXTERIOR SECTION 27
1. BODY COLOR 27
Body Color 27
2. BODY PAINT 27
Body Paint 27
3. CONDITION OF FIBERGLASS & FIT 27
Fiberglass & Fit 27
4. TOP 28
4A. HARDTOP 28
Exterior Moldings 28
Rear Window 28
Side Windows 28
Weatherstrip, Window Channel & Side Window Seals 28
4B. SOFT TOP 28
Color & Material 28
Stitching & Bindings 29
Rear Window 29
Warning Label 29
5. WINDSHIELD GLASS & TRIM 30
Windshield Glass 30
Frame & Gasket 30
6. SIDE DOOR GLASS & METAL SURROUND 30
Side Door Glass 30
7. COWL VENTILATOR & WIPERS 30
Cowl Vent 30
Wiper Blades 30
Washer Nozzles 30
8. FRONT, REAR & SIDE EMBLEMS 31
Front Emblems 31
Side Emblems 31
Rear Emblems 31
9. FUEL FILLER AREA & GAS CAP 31
Filler Area Paint 31
Rubber Items & Clips 31
Gas Cap 32
10. GRILLE ASSEMBLY & RADIATOR FRONTAL AREA 32
Grille Frame, Center Bar, Grille & Teeth 32
Front Radiator Area 32
Horns 32
11. FRONT BUMPER AREA 32
Front Bumpers 32
Vertical Bumper Guards 33
License Plate Holder 33
Verticle Bumper Support Brackets 33
12. HEADLAMP ASSEMBLIES 33
Headlamps 33
Lamp Bezels 34
13. PARKING LAMPS 34
Parking Lamps 34
14. BODY SIDE TRIM & MOULDINGS 34
Moldings 34
Air Scoop 34
Door Handles & Locks 34
15. REAR BUMPER AREA 34
Vertical Bumpers 34
Tail Lamps 35
Trunk Lock 35
Rear License Plate Bracket 35
16. RADIO ANTENNA 35
Exterior Mounting 35
Interior Mounting 35
17. EXTERIOR REAR VIEW MIRROR 35
Exterior Mirror 35
18. WHEELS (including spare) 36
Wheels 36
19. WHEELCOVERS 36
Wheelcovers or Hubcaps 36
Ornaments 36
20. TIRES (including spare) 37
Tires 37
21. UNDERBODY & WHEELHOUSES 37
Underbody 37
Wheelhouses 37
Splash Pans 37
22. Overall Cleanliness 38
Overall Cleanliness 38
MECHANICAL SECTION 39
1. ENGINE COLOR 39
Engine Color 39
2. ENGINE BLOCK 39
Engine Block Casting Numbers 39
Engine Block Casting Date 39
Assembly Identification Stamping 40
Stamp Pad Surface Finish 41
3. CYLINDER HEADS 41
Cylinder Heads 41
4. VALVE COVERS 42
Valve Covers 42
1956 42
1957 43
Gaskets, Screws, Washers & Clips 43
5. AIR CLEANER ASSEMBLY 44
Carbureted Air Filter 44
Fuel Injection Air Cleaner 44
6. FUEL SYSTEM & INTAKE MANIFOLD 44
Carburetors 44
ID Tags 46
Intake Manifold 47
Thermostat Housing 47
Fuel Injection Unit 47
Thermostat Housing 48
7. ACCELERATOR LEVER & LINKAGE 48
Accelerator Lever on Firewall 48
Linkage & Springs 48
Powerglide Throttle Linkage 49
8. OIL FILLER TUBE, CAP 49
Oil Filler Tube 49
Oil Cap 49
9. FUEL PUMPING SYSTEM 49
Fuel Pump, Bolts & Adapter Plate 49
Fuel Filter 49
Fuel Lines 50
10. IGNITION DISTRIBUTOR & COIL 50
Ignition Distributor 50
Ignition Coils 50
11. SPARK PLUG WIRING & RADIO SHIELDING EQUIPMENT 51
Wire Supports, Grommets & Heat Shields 51
Ignition Shielding 52
Spark Plug Wires 52
Ground Straps & Capacitors 52
12. EXHAUST MANIFOLDS & PIPES 53
Exhaust Manifolds 53
13. ENGINE OIL 53
Ventilator Pipe 53
Dipstick Tube & Pressure Line & Fittings 54
14. MOTOR MOUNTS, WATER PUMP, FAN BELT 54
Motor Mounts 54
Water Pump 54
Fan Belt 54
15. OVERALL CLEANLINESS 54
Overall Cleanliness 54
CHASSIS SECTION 55
16. ELECTRICAL SYSTEM 55
Generator 55
Mount & Brace 56
Tach Drive Cable 56
Voltage Regulator 56
Horn Relay 56
17. ELECTRICAL WIRING HARNESSES 56
Main Harness 56
Ballast Resistor 56
Generator to Regulator Harness 56
Temperature Sending Unit 57
Power Top / Window Circuit Breaker & Wiring 57
18. BATTERY & CABLES 58
Battery 58
Retainer & Fastners 58
Cables & Felt Washer 59
19. HEATING SYSTEM 59
Heater Air Hose 59
Heater Coolant Hoses 59
Inlet Plenum or Block Off 59
20. WIPER MOTOR & WASHER SYSTEM 60
Wiper Motor 60
Washer System 60
21. BRAKE SYSTEM 61
Master Cylinder 61
Brake Lines & Blocks 61
Park Brake Cable 61
22. ENGINE COMPARTMENT BLACKOUT PAINT 62
Blackout Paint 62
23. UNDERSIDE of HOOD PAINT & WEATHERSTRIP 62
Paint Color 62
Paint Margin 62
Hood Weatherstrip 62
24. HOOD HARDWARE 62
Hood Hinges 62
Hood Support 63
Rear Latches & Hood Lock 63
25. ENGINE COOLING SYSTEM 63
Radiator Fan 63
Water Pump Pulley 63
Crank Balancer Pulley 63
26. RADIATOR SYSTEM 64
Radiator & ID Tags 64
Hoses & Clamps 64
Pressure Cap 64
Fan Shroud 64
27. FRONT SUSPENSION & STEERING 65
Front Suspension 65
28. STARTER SYSTEM 65
Starter Motor 65
Solenoid 65
Powerglide Relay 65
29. OIL PAN & FILTER 66
Oil Pan 66
Oil Filter Housing 66
Filter Screen Instruction 66
30. TRANSMISSION 66
30 A. Automatic Transmission 66
Filler Tube 66
Neutral Safety Switch 66
30 B. Manual Transmission 66
Bellhousing 66
Clutch Linkage 66
30 C. Speedometer Cable 67
31. CHASSIS & REAR AXLE 67
Frame, Brake & Fuel Lines 67
Frame Stencil 68
Rear Suspension 68
Mufflers, Tail Pipes & Hangers 68
32. OVERALL CLEANLINESS 69
Overall Cleanliness 69
33. REAR AXLE RATIO CODES 69
34. FINAL MONTHLY SERIAL NUMBERS 70
35. OPTIONS & ACCESSORIES 71
36. COLOR AND TRIM COMBINATIONS 73
OPERATIONS SECTION
Engine Off & Cold, Hood Open, Air Cleaner in Place, Car in Neutral or Park, Park Brake Set. Run Engine until # 25.
1. Ease of Start
There should be no excessive cranking of the engine to achieve start, although fuel injected models will normally require a little more time. Starter drag or engine backfire are deductible items. Judges are to note function of the choke operated fast idle at this time. If applicable, refer to Judging Reference Manual Section 2 # 19 for failure to start or lack of fuel.
2. Choke Function
On a .cold. engine, the choke and fast idle mechanism will .set. itself by depressing the throttle prior to engine start. Choke will activate in any temperature, even in desert heat.
3. Fast Idle Speed
Depending upon the ambient temperature, a fast or faster than normal idle will be observed upon start.
4. Exhaust Sound, Leaks, Smoke
Check in the engine compartment and underneath the car for leaks. Above normal amounts of smoke generated by engine wear or malfunction, or excessively rich fuel calibration or malfunction are cause for deduction.
5. Water, Fuel, Oil Leak
During all phases of the Operations check, judges and owners remain cognizant of fuel leaks, as opposed to minor signs of fuel staining. Should this occur, the owner must immediately shut off the engine. Additionally, no radiator cap is to be removed during any phase of the operations judging.
Judge this section both before and after STOP ENGINE. Check in the engine compartment and under the car. Very minor seepage of oil around seals is not deductible.
6. Slow Idle Speed
Once the engine is warm and the throttle is again depressed, the fast idle cam should retract to the warm or idle position. At this point, the engine should continue to run smoothly at the slow, normal idle speed.
7. Engine Noise, Vibration, Blow By
Unusual noises encompass such things as squealing fan belts, excessive valve lifter clatter, all 1956 and some high HP 1957.s have solid lifters, defective transmission bearings and notice-able internal engine noise which may be caused by excessive wear or impending mechanical failure.
8. Windshield Washers
Works with the key on, manual foot operated fluid pump, mechanically coordinated. To operate, depress foot pump, which will squirt a quantity of fluid on the central viewing area of both driver and passenger side of the windshield. Depression of pump, through a cable, will also cause wipers to operate until pump pedal is released, at which time they will return to the park position.
9. Windshield Wipers
Work with the key on, two speed electric, cable controlled. Clockwise rotation of wiper knob turns them on to slow speed, further rotation for high speed. Counterclockwise rotation causes blades to return to park and stop. After approximate 1957 Serial # 1400 a “slow park” feature was introduced where the wipers exhibit a noticeable pause about six inches above the central windshield trim, followed by a slower, more controlled return to the park position.
10. Horns & Contact
Check for proper function of both high and low note horns mounted in grille area.
11. Park Lights
By pulling headlight switch to first detent, the park lights turn on. The rear tail lights also turn on. The park lights will only operate in this mode, not when headlights are on.
12. Headlights, High & Low Beam
Pull headlight switch to full on position. Check for high and low beams.
13. Front Turn Signals
Work only with key in the on position. The two front park lights function as turn signal lights when activated by the turn signal lever on the steering column.
14. Tail Lights
The tail lights work with the key on or off and will operate with the light switch in the park position or the full on position.
15. License Lights
The license lamps illuminate by pulling the light switch to the park or full on position.
16. Rear Turn Signal Lights
The rear turn signals utilize the left or right brake light filaments and will be noticeably brighter than the tail lights. They operate by activating the turn signal lever on the steering column. They work only with the key on.
17. Brake Lights
With the key on or off, a slight depression of the brake pedal activates the rear brake lights. The brighter of the 2 filaments is utilized as the brake light.
18. Park Brake Function
With the park brake full on, in an appropriate gear, carefully attempt to move the car forward or backward to demonstrate the proper park brake function. The car should not move with engine at idle speed.
19. High Beam Indicator & Turn Arrows
Pull headlight switch to full on position and depress the floor dimmer switch. The red indicator light on the dash will illuminate to indicate the high beams being on. Check for green directional arrows on dash when activating the turn signals.
20. Turn Signal Canceling
With turn signal activated, turn steering wheel to left and right and return to center. Turn signal should turn off when wheel is returned to center position.
21. Gauge Operation
Check gauges for proper function, fuel, temperature, ammeter, oil pressure and tachometer. Unusual gauge reading or needle flutter should be noted and appropriate deductions made.
22. Tachometer Operation
Tachometer should work with engine running. Check for needle flutter or excessive noise in tachometer.
23. Park Brake Alarm (optional)
Works only with the key on. Equipped with a switch mounted flasher. In some cases may require up to one minute to begin flashing. It will remain lighted during warm up period.
24. Heater & Defroster (optional)
Rotate fan control to left for slow speed, right for high speed. Pull out temperature control and note air temperature change. Pull out defroster control to check for diverting air to the defroster duct outlets. Pull out air control during this check to check for additional flow and heat. Check at heater core for any sign of leakage.
25. Radio
(Standard equipment until April 1956 then optional)
Turn on by left knob which is on-off & volume control, allow radio to fully warm up. Right knob is manual station selector. Adjust both volume and confirm basic operation. With a strong station check the tone control located behind the volume control. The sensitivity selector is a winged handle under the right tuning knob. Start with middle position and see if radio seeks a station. Moving the selector to the left, the radio should only seek out strong stations. Fully to the right will result in more stations being checked. In remote areas the middle or right selection might result in constant scanning.
STOP ENGINE
26. Clock
Check clock for proper operation. Care should be taken to listen to the operation, confirming that it hasn’t been converted to a quartz movement. Check function of time set knob.
27. Courtesy Lights
Will operate with ignition on or off. A plunger style remote switch in each door hinge pillar activates the light when either door is opened.
Also check for operation by turning light switch all the way counterclockwise.
28. Seat Adjustment
Adjustment is made by pulling up on locking lever on front outboard side of each seat, and manually moving the seat forward or backward. Check to see that the seats lock in position.
29. Neutral Safety Switch or Reverse Lockout
Cars equipped with an automatic transmission are fitted with a switching device which will allow function of the engine starter only when the transmission is in Park or Neutral. Carefully confirm its proper function.
30. Ignition Switch
On 1956 & 1957 Corvettes the ignition switch has 4 positions. Lock, Off, On, Start. Check for operation and also check to see that the key can be removed when the switch is in any position. If the key was removed in the off or on position, in order to move to the lock position, the key must be reinserted.
31. Cigarette Lighter
The standard equipment lighter works with the key on or off. After being depressed, the lighter automatically functions by popping out after temperature is achieved. The lighter element should visibly glow.
32. Cowl Vent
The cowl vent locks in three positions, with the third being full open. Three clicks will be audible as the vent is opened. Check for binding or mechanical interference.
33. Stowage Compartment Latch & Lock
Located between the seats, the lockable door should open and close smoothly. The ignition key is utilized for locking and unlocking. The locked position is vertical with the key teeth down. To unlock, rotate clockwise 90 degrees with key teeth facing passenger.
34. Windows
Standard manual window cranks should operate smoothly to raise and lower the side windows without excessive effort. Binding should not be apparent. Check for play in the regulator and window sealing capability.
Optional power window equipped vehicles are fitted with a dual switch on the drivers door and a single switch on the passenger door. They operate with the ignition key in the on or off position. Check that all switches are functional. They are spring loaded and return to center position upon release.
35. Doors & Trunk Latching & Locking
Both doors may be locked and unlocked from the outside by means of the ignition key. Drivers door locks by rotating key clockwise towards rear of car; passenger door by rotating counter clockwise towards rear of car. Inside operation is achieved by rotating the lock mechanism knob. Excessive effort should not be required.
Exterior door handles are push button type; interior door unlatching is accomplished by pulling back on the pull type knob. Both inside and outside door handles should operate smoothly, and the doors should not have to be slammed shut.
The trunk is unlocked with the ignition key, teeth facing down and rotating the key clockwise. Excessive effort should not be required and the lock housing bezel should not rotate.
36. Interior Lights
Check for operation of dash lights in the following: Cigarette lighter well, speedometer (2 bulbs, left and right), tachometer light, clock light and the small gauge clusters. Each of the (two gauge) clusters share one bulb.
The radio dial light is wired independently of the receiver and will illuminate regardless of key position.
Check illumination and dimming function of all lights by rotating the headlight switch, which is equipped with a rheostat. Counterclockwise turning brightens lights, clockwise, dims. The lights should not flicker during rotation.
INTERIOR SECTION
1. SEATING AREA
Seats, Backs and Trim
Upholstery is a fine “hair-cell” leather grain vinyl, called .Elascofab.. The seats have a “hot pressed” waffle pattern central panel on the backrest and cushion, framed by a smooth bolster. Original waffle pattern central panels have a distinctive pattern, in that each was pressed separately and not cut from running waffle yardage. In some corners, square waffles change to triangular shaped imprints. Stitching color matches upholstery. Refer to the charts at the rear of this manual for correlation of interior trim color to exterior body color.
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Seat Belts
Seat belts were a dealer installed accessory. Do not deduct for incorrect seat belts, or lack thereof, as they were not factory installed and are considered safety equipment.
Adjustment Handle and Tracks
Seat track adjustment lever is chrome plated metal, located on the outboard front corner of each seat.
2. CARPETING
Carpet Color
Refer to charts at rear of manual for color combinations.
Carpet Weave
Carpeting should be installed so that weave runs diagonal to vehicle centerline. Correct weave is low loop. Carpet should fit flush to the floor with little or no bulges. The carpet is glued in place.
Carpet Binding & Heel Pad
Binding is leather grain vinyl matching carpet color. Driver’s heel protector pad is leather grain vinyl; black with red carpet (although a red heel pad with red carpet may have appeared on some cars), brown with copper (dark beige) carpet. Dimmer switch bezel is black rubber with red carpeting; may be painted to match copper carpeting.
Retaining Screws & Dimmer Switch Bezel
Size # 8 carpet retaining chrome oval-head Phillips are used through the floor. They have # 6 size finishing washers and the locations varied Two at the top and bottom inboard toe location, each side, would be considered normal, however, additional screws, up to six or eight total, may have been used on some cars.
3. TRANSMISSION SHIFTER ASSEMBLY & CONSOLE AREA
Shifter, Boot & Knob
Transmission shifting levers all have the same appearance; a round, tapered chrome shaft. The shaft passes through a black rubber dust shield which is mounted at the left side of a bright metal rectangular floor bezel containing a shift pattern diagram plate at its center, and a removable ash tray incorporated on the right. Rubber dust shield boot uses round shaft opening, not slotted as with later boot for four-speed shifter with reverse lock-out.
Shift lever spherical knobs appear generally as follows for all available transmissions: Early 1956 Corvettes to an unknown point (approximately 2/22/56) used a white tenite plastic knob; Later 1956 production to early 1957 production (approximately serial number 200) used a 1-1/ 2" diameter chrome steel knob; remaining 1957 production appears to have reverted back to the white tenite knob. It should be noted that chrome steel knobs have been found on some later model 1957’s. A hex nut without a lock washer was used as a jam nut under the shifter ball.
Floor Plate & Pattern Plate
The transmission shift pattern diagram plate for the 3-speed and Powerglide was made of zinc base diecasting or sheet zinc from start of production 1956 through approximately 1957 serial number 400. Later 1957 production shift pattern plates, including the 4-speed (introduced about May 1, 1957), are made of aluminum. The shift patterns are etched into the plate, and the pattern is highlighted in black paint. The shift pattern for the Powerglide was changed during 1956 as illustrated. Small chrome plated phillips head screws secure the shift pattern to the floor plate.
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1957 Ash Tray
The ash tray uses a spring-loaded lid with separate lid lift-knob which is chrome, not black. Interior of ash tray contains a cigarette snuffer, but does not contain cigarette holders.
[pic]
Correct 1956-57 floor console plate is located at left. Incorrect later design at right has rounded rear corners.
[pic]
1956-57 ashtray did not use cigarette holders as pictured at right.
4. INSTRUMENT PANEL PAD
Instrument Pad
Color should match vehicle interior color. Pad is made of same leather grain vinyl as seats and door panels.
Sewing & Fit
Pad may fit against instrument panel with slight gaps (up to 1/4. approximate). Pad ends at windshield butt are sewn as illustrated with approximately seven stitches per inch.
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5. INTERIOR MIRROR AND DEFROSTER OUTLETS
Interior Mirror
The stainless steel backed inside mirror is adjustable for vertical height, and two types were used. Generally, the 1956 Corvette uses a mirror base containing a thumbscrew, while 1957 uses a threaded base and shaft with chrome locknut; however, some overlap of mirror design usage may have occurred near model-year change. Mirror base mounts with point of teardrop facing forward; mirror head mounts with pivot at lower position. Mirror glass is shaded, and does not contain date coding or manufacturer identification. The mirror back is attached to the stem with two rivets, some 1957 mirrors will appear with three rivets and may display the “S” within a circle logo.
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Pictured mirror is 1957 variety; earlier version used a thumb screw at arrrow location for height adjustment, rather than lock nut.
Defroster Outlets
Windshield defroster outlet escutcheons are chrome, not painted, and all cars are so-equipped; even those without heater equipment. Also, although the Factory Assembly Manual for this series indicates otherwise, some authentic examples without heater equipment do have metal defroster inlet ducts mounted on the underside of the upper instrument panel.
6. UPPER & LOWER INSTRUMENT PANEL PAINT
Upper Panel Color & Gloss
Upper instrument panel is painted in exterior body color; except on Polo White models which use a red upper instrument panel surface, matching the red interior trim. A Chevrolet specification calling for a white upper instrument panel on 2nd design 1957 Polo White Corvettes with red interior or late 1957 Polo White with beige interior can be found by referring to the color chart at the rear of this manual. The upper instrument panel color was dulled with flattening compound in varying degrees from semi-gloss to flat.
Lower Panel Color
Refer to charts for lower instrument panel color. Note that the Chevrolet color chart for the 1957 Corvette specifies that later production lower instrument panels were to be painted beige, regardless of interior/exterior color combinations; however, evidence indicates that this specification may not have been followed for every red interior car.
7. STEERING WHEEL, TURN-SIGNAL SWITCH & MAST ASSEMBLY
Steering Wheel & Horn Button
The competition-type steering wheel uses a plastic rim molded with a leather grain, color-molded to harmonize with the interior trim (see color charts at the rear of this manual). The wheel has a center horn button, and three flat stainless steel spokes with circumferential finishing marks on the top side (radial direction on the bottom). The steering wheel is positioned at 10, 2 and 6 o’clock with the wheels straight ahead.
[pic]
Turn Signal Housing & Lever
The steering wheel hub and direction signal switch housing are painted gloss, same color as lower instrument panel (see color charts). Turn signal lever is chrome with a 9/32” thick chrome hex nut and may have a lock washer; lever knob is white plastic.
Steering Column Mast
The steering mast jacket (to steering gear housing) is painted gloss, same color as lower instrument panel (see color charts). Examples are known where beige columns were over-painted red at the factory.
Note that there should be a distance of 4" between the instrument panel and turn signal housing base. A smaller distance might indicate steering column replacement or modification, possibly for racing purposes.
8. INSTRUMENTS & CONTROLS
Tach, Speedometer, Lighter & Gauges
The battery-amp, oil pressure, fuel, and temperature gauges all have a chrome button in the center, and use rounded pointers and dot-markers as opposed to later model gauge line-markers. The fuel gauge has a red tag attached to the rear terminal, which is printed “connect sender wire to this terminal. Warning if hot wire touches sender will be damaged!” Standard 6,000 RPM tachometer, without redline, has an engine revolution counter. Speedometer registers speed to 140.
1957 Corvettes equipped with RPO 579E (283 HP with FI and cold air intake) used a steering column mounted AC 8,000 RPM tachometer. This tach and its mounting hardware were normally painted in lower instrument panel color (see 1957 color chart). The vacant instrument panel tachometer opening normally utilized an exterior body emblem on these models.
[pic]
Standard 6000 rpm tach with revolution counter is pictured at left; RPO 579E, 8000 rpm tach mounts to steering column. The tach bracket has the vendor logo “AMSCO” stamped into the upper portion.
The cigarette lighter was made by CASCO. It has a short heating element with a ceramic spacer behind the heating element. There is a guard over the element and a cone shaped washer between the knob and housing.
Ignition Switch
The ignition switch used a black plastic bezel with ”LOCK”, “OFF”, “ON”, and “START” in white lettering for switch position identification. All 1956’s, and early 1957’s to approximately serial number 1900, used a chrome backing rim with the bezel; later 1957’s did not.
Controls & Handle
Control knobs on the instrument panel are knurled stainless steel over black plastic, same design as used on the 1956 Bel Air. The three heater control knobs for optional fresh-air heater contain function identification.
Hood release is a chrome plated torpedo-shaped T-handle reading “HOOD LATCH” (letters painted black) with control cables crimped into the assembly.
9. RADIO, CLOCK, HEATER CONTROLS
Radio
The factory accessory radio (FOA 102) is a signal-seeking type with favorite station selector push-buttons. The signal-seeking touch bar is plain for 1956, while 1957 is engraved “WONDER BAR”. Either design of touch bar is acceptable for a vehicle near model year change.
Dial tuning indicator is white, same as frequency numbers. Frequency scale contains Chevrolet bow-tie emblem and Conelrad marks. Radio uses clear plastic identification bezels marked “VOLUME” and “SELECTOR” behind control knobs, and chrome plated tone and sensitivity winged ring knobs.
Corvettes without radio equipment have a radio receiver block-off plate in the instrument panel, painted lower instrument panel color. A die-cast plate with a single straight horizontal bar was used for 1956 and 1957; however, another plate, resembling a “starburst”, may also have been used on cars below (approximately) 1957 serial number 4100. Further, non-radio equipped cars used a black cardboard cover behind the speaker grille (with a “W” within a circle), filling the area used for the speaker and power supply unit. Full credit for authentic non-radio models.
Speaker/Power Supply
The speaker unit behind the instrument panel contains the radio power supply, with tube/s mounted horizontally. Tubes are covered with individual metal housings. Wiring should exit the radio unit on the speaker/power supply side. Other routings are passenger car applications. A transistor style power supply was utilized in later 1956 and 1957 with 50 cent sized transistors and three small transformers.
[pic]
Above: Signal seeking radio tuning bar is plain on 1956, engraved “Wonder Bar” in1957. Dial indicator is white.
Below: On non-radio equipped vehicles, an example of the die cast “straight bar” radio block off plate; speaker and power supply cover installation is at right.
[pic]
Speaker Grille
Radio speaker grille upper portion is painted dull black (not chrome) within chrome bezel with central blue painted Chevrolet “bow-tie” within a red, white and chrome shield emblem. Lower speaker grilles are painted same color as lower instrument panel; not chrome or black.
Clock
Check clock for correct Corvette application, not passenger car substitute. The Corvette clock has “F” on the left of the fast & slow adjusting screw.
Heater Controls
Corvettes without accessory heater equipment use three dummy control knobs (with bushings) which, lack function identification, each fastened to the instrument panel with a square nut and washer. Early 1956 models with re-circulating air type heater (to approximately serial number 1210) use a functional “PULL DEFROST” blower motor knob to the right of the speedometer housing, and dummy knobs for both temperature and air control positions (as used with later fresh-air heaters). [pic]
10. PEDALS & AREA UNDER INSTRUMENT PANEL
Heater & Defroster Hoses
Early 1956 models (to about serial number 1210) used 1955 Corvette re-circulating air heaters. An outside fresh air heater, improving air distribution and reducing the tendency of windows to fog, was then used shortly after start of production 1956. The fresh air heater air distribution box is made of formed cardboard, not metal. Defroster air hoses are fabric covered coiled wire.
Cowl Vent
Cowl vent mechanism is painted semi-gloss black, using a chrome knob; however, some early-1956 may appear with white plastic knob, same as 1953-55 design. Aluminum instrument panel side cowl supports appear on 1957 models, above approximately serial number 4300.
Insulation
Firewall insulation is black to dark-gray fiberboard with a laminated layer of insulation material, and is secured to firewall with rubber push fasteners. The insulation carries a manufacturer’s logo which is viewed as an .M. or .W. within a circle. Heater equipment was an accessory (FOA 101) and cars without heater equipment will have insulation covering the heater opening below the instrument panel. Check for aluminum cowl bracing, which was installed in 1957 about serial number 4340-4360, and continued until the end of 1957 production.
Wiring
Generally, all 1956 and early 1957 harness connectors are opaque Tenite II; remaining 1957’s are generally tan ABS plastic, except for some possible black usage during mid-1957.
On all 1956 and early 1957.s up to 12/18/56 the turn signal flasher was mounted on the lower instrument dash panel reinforcement bar just to the right of the steering column. After 12/18/56 the turn signal flasher was mounted on the cowl vent bracket. Turn signal flasher should be Tung-Sol AP 273 or Signal-Stat ZN232.
Deductions are appropriate for loose wires hanging below the instrument panel, or interior paint overspray on cowl vent mechanism, park brake lever sleeve, wiring, control and drive cables, etc.
Pedals & Pads
The correct clutch and brake pedal pads have vertical ribs, as does accelerator pedal. Windshield washer pump pedal (on cars so-equipped) uses a black rubber foot pad containing vertical ribs. The brake pedal on automatic cars is 2 ½” x 4” which is much larger than standard transmission cars.
[pic]
Parking Brake Alarm Courtesy Lights
11. PARKING BRAKE ALARM, COURTESY LAMP, DOOR SWITCH
Parking Brake Alarm & Handle
The parking brake alarm was an accessory (FOA 107). An alarm light with a red lens is located just below the speedometer. The alarm actuating switch and lamp flasher unit mount to the parking brake shaft sleeve, under the instrument panel. The wiring is tan in color, with a fuse located at the accessory junction block. Parking brake T-handle is chrome with vertical ribs.
If the vehicle is not so-equipped, a chrome metal plug (with flat surface, not convex) will cover the alarm light opening, and full credit can be given. However, deductions are appropriate if partial evidence of this accessory remains.
Courtesy Lamp & Door Switch
Courtesy lamps are mounted on each side, below the instrument panel. The lenses are white plastic, not clear. Although courtesy lights were an accessory (FOA 108), lamp openings exist even in those vehicles not so-equipped. Also, body harness contains wiring provisions for courtesy lights on vehicles not equipped.
The remote door opening switches used with courtesy lights mount in the door jamb area, and locations varied. These switches are unpainted and normally use brown plastic contact buttons. No switch mounting holes should appear on vehicles not so-equipped.
[pic]
This original example of the door jamb area shows excessive application of brush applied weatherstrip cement.
[pic]
Top rear of door weatherstrip is secured with a small metal clip attached under the rear upper door bright garnish molding.
12. DOOR OPENING AREA, DOOR WEATHERSTRIPPING
Door Jambs, Hinges & Lock Pilars
Door threshold, lock pillar filler panel, and door jamb areas including hinges, are painted in exterior body color. Also, the door rear end metal access covers and attaching screws are normally painted with exterior body color. The two large Phillips screws with tooth-washers at the end of each door (used to attach the inner door window rear run channel) are not painted, all other screws on rear of door are painted exterior body color.
Door Latches & Strikers
The unpainted cad plated door latch and unpainted striker were masked off during factory painting so slight overspray near edges is acceptable. The striker has a unique rubber bumper on inside area, held in place by a plated Phillips screw.
Sill Plates
Door threshold sill is stainless steel, and a textured stainless steel step plate (same design as lower door scuff protector) is located at the base of the lock pillar filler panel.
Weatherstrips & Cowl Gutters
Door perimeter weatherstripping contains a visible “S” (within a square) manufacturer’s logo molded into the rubber. This weatherstripping is cemented with brush-applied adhesive which appears yellow and may be excessive in its application. Also, a number of button-head push fasteners were used at the upper portions, both front and rear. The top rear end of each door perimeter weatherstrip is secured with a small metal retaining clip attached either under the rear upper door bright garnish molding (as pictured) or below the fiberglass lip. [pic]
Corvettes built after 1956 serial number 3844 (8/8/56) used newer side door weatherstripping for improved sealing. With late 1957 production a longer cowl gutter seal was applied to the underside of the cowl lip; earlier production 1956-57 Corvettes used a short gutter seal, which was applied to the top of the cowl lip. It should be noted that many early models may have been dealer retrofitted with these later door and/or cowl seals to correct water leak problems (as directed by the factory), and a moderate deduction is appropriate for such retrofit. Deductions are appropriate for missing pieces; condition of rubber; paint overspray on weatherstrips; and obvious replacement items.
13. DOOR PANELS & COWL KICK PANELS
Door Panels
Refer to the charts at the rear of this manual for correct trim color combinations. Leather grain vinyl covers the upper door garnish molding which is continuous with the instrument panel crown. Forward edge, which meets butt of dash crown pad, is sewn as illustrated. Door panel upper sidewall vinyl panels and cowl side kick panels are trimmed in waffle pattern leather grain vinyl. Door and kick panels have a distinctive pattern, in that each was pressed separately and not cut from running waffle yardage. In some corners, square waffles change to triangular shaped imprints. Also, in some areas, waffle pattern stops and does not extend to, or around, edges. The panels were attached with chrome plated #6 phillips oval head screws with finishing grommets which are crimped into the panel.
Door Panel Metal Moldings & Scuff Plate
A stainless steel horizontal decorative molding divides the door sidewall just above the built-in armrest, then slopes down toward the floor. A stainless steel textured metal scuff protector panel, at the bottom of the door, extends rearward from the decorative molding.
[pic]
Note the triangular imprint at the edge of waffle material in the above photo of an original door panel. Note the lower row of waffles shows absence of waffle square at the rear of this original kick panel.
Kick Panels
The cowl side kick panels have a rolled vinyl windlace at the edge of the door opening and are attached by oval-head chrome Phillips screws with metal finishing eyelets crimped into panel.
Arm Rests & Painted Upper Door Trim
The armrest and lower panel are in leather grain vinyl without the waffle pattern. A metal hand-grip insert, painted interior color, is used at each arm rest.The wide metal door trim panel is painted as a continuation of the lower instrument panel, thus matching the lower instrument panel in color (refer to color charts).
Interior Door Controls
Door release knobs are plain off white plastic. Manual window cranks, forward of the arm rest, are completely chrome. Power window equipped models use smooth chrome push-button regulators located below and forward of the interior door opening knobs; the driver’s door using a dual switch, passenger using a single. The inside door lock levers are chrome and should point towards the rear of the door.
14. DOOR WINDOW REVEAL MOLDINGS & WINDOW POSTS
Upper Door Trim & Felts, Seals & Stops
Side door window reveal garnish molding is polished stainless. Door end stainless molding attaches from the bottom. Inner and outer door window felt seals are attached to moldings with staples, not rivets. Original inner and outer horizontal window felt seals used a large diameter stainless steel beading (5/32" OD) which slipped over the smaller bead (I/8" OD) of the vertical felt channel.
Door Window Posts & Liners
A fixed, felt-lined window run channel with white stitching is riveted and screwed to the post. The top two attachments are rivets and the lower attachments are phillips head screws. At an unknown point about model year change a side-door-window-to-pillar-post seal was added at the top of the window post, riveted with the window run channel. This window-to-pillar seal may have been dealer retrofitted on earlier 1956 models, and a moderate point deduction is appropriate for this retrofit.
15. TOP COVER TRIM, SEAT SEPARATOR & PACKAGE COMPARTMENT
End Straps
The top compartment end straps are of the same vinyl and color as the seat upholstery; backing on underside is black with beige trim, gray with red trim. When the compartment lid is closed, these end straps snap to the top of the door lock pillar at the outer edge of each seat back. Early-1956 end straps use a round snap; later production through 1957 utilize a slotted channel snap.
Top Cover & Seat Separator Moldings
Cockpit garnish moldings at forward edge of the top cover are bright stainless, with moldings continuing down seat separator. Top cover opening button and ferrule as well as package compartment lock release button and escutcheon are bright metal.
Seat Separator & Package Compartment
Seat separator and interior of package compartment are painted exterior body color, not contrasting interior color. The seat separator lid is attached to the hinge with two clutch head screws painted exterior color. Four phillips head screws hold the stainless steel trim moldings in place and are unpainted.
16. INTERIOR ROOF AREA
16A. Interior of Hard Top
Headliner
The vinyl headliner is the same waffle pattern material used for the seats and door panels, matching interior trim color. The headliner is glued in place.
Front Latches
The correct front hold-down latches for 1956-57 have a shorter, more curved handle than the longer handled latches used with later models and as replacements (longer handle replacement variety may mar the 1956-57 headliner).
Side Locator Pin Receivers
Two designs of hardtop side locating pin receiver moldings were used. From start of production 1956 through early 1957 (approximately serial number 2500) a round hole molding was used just rearward of the doors. Later production 1957.s used a molding containing a slot, which allowed for hardtop fore and aft adjustment.
Interior Header, Moldings & Mounting Brackets
Side horizontal interior metal trim initially snapped into place, then changed to additional attachment with screws, three per side. Date of this addition is unknown. At rear of the hardtop, three hex-head shoulder bolts are used to secure it to the convertible top compartment cover (left, right and center). The interior moldings snap into place on ‘56 to mid ‘57 hardtops. Mid to late ‘57 show screws as the attaching method.
Convertible Top Rear Latches (if equipped)
The presence of rear convertible top latches should be checked if the vehicle is being judged with a hardtop, but also has a stored convertible top.
Correct 1956 through mid-1957 production (approximately serial number 4500) use 1st design latches containing integral attaching studs. Later 1957 production may use either 1st design latches, or 2nd design, which attach with separate Phillips-head screws.
Approximately April 1, 1956, a Corvette could be ordered with an auxiliary hardtop in place of the convertible top. Vehicles equipped with hardtop only will not have rear convertible top latches mounted on the convertible top storage compartment cover, and will not have soft top bracing supports behind the seats. Deductions are appropriate for hardtop-only models equipped with rear convertible top latches. Full credit can be given for hardtop-only vehicles, if there is no soft top evidence.
16B. Interior of Soft Top
Front Latches
The correct front hold-down latches for 1956-57 have a shorter, more curved handle than the longer handled latches used with later models and as replacements.
Rear Latches
Correct 1956 through mid-1957 production (approximately serial number 4500) use 1st design rear latches containing integral attaching studs, which mount to top compartment cover. Later 1957 production may use either 1st design latches, or 2nd design, which attach with separate Phillips-head screws.
Bows, Pads & Straps
Convertible top bows are painted gloss enamel to match soft top headliner color.
The White and Black soft tops have black pads and headliner; Beige top has beige pads and headliner (possibly changed to black pads and headliner approximately March .57).
Hold up straps connect lower rear bow to main bow above rear window (strap attached to lower rear bow with two chrome Phillips-head machine screws and gloss black painted retainer plate with vertical center indentation. Snap fastener loops are attached with round indented slotted head screws outboard of rear straps, and are used to secure lower rear bow to main bow when top is to be lowered into top compartment.
Door Window Weather Seals
Convertible top side rail weather seals should provide good contact with top of raised side door glass. Door window weather seals are black cloth-covered.
Front Header
Most 1956 convertible top front headers use a three-piece weather seal; late-1956 and 1957 uses a one-piece seal.
Rear Bow Seal
The rear bow seal is a mohair covered round foam design, which matches the interior top color, the rear catches should be properly adjusted to provide a seal between the rear bow and the top compartment cover.
17. TRUNK SECTION
Trunk Color & Paint Application
Trunk compartment interior area and underside of trunk lid paint color should match interior trim color. Trunk fender cavities may not have been directly painted, but rather oversprayed. Paint margin of exterior body color and trunk lid underside trim color is covered by trunk lid weather-strip.
Weatherstrip
Trunk lid weatherstripping is of the same type as door seal, containing an .S. (within a square) manufacturer.s identification logo. It was installed to trunk panel inner lip with the seam located at the bottom center, adjacent to latch mechanism. Yellow adhesive was brush applied and may have been excessive. Weatherstripping should not show signs of paint overspray.
Wiring
Deductions are appropriate for any wire harness splices or paint overspray. Note: Radio antenna base and cable are not judged in this section.
18. HINGES, LATCHES, DIVISION PANEL, SCREWS & CLIPS
Hinges
Spring-loaded trunk lid hinges are painted trunk color along with their attachment bolts, flat washers and lock washers.
Latches
The cadmium-plated trunk lock mechanism is normally fastened to the trunk lid with two clutch-head machine screws, two recessed hex-head bolts with flat washers, and one large phillips head machine screw with an external tooth lock washer. The adjustable latch striker (also cad-plated) is attached in the trunk with two hex-head bolts.
[pic]
[pic]
|Mat Number |Mat Color |Mfg. ID |Trunk Color |
|4645541* |Red |"Baldwin" |Red |
|4647685* |Beige |"Baldwin" |Beige |
|3723065* |Black** |"Baldwin" |Beige |
|3723710*** |Red |"US" |Red |
|3725404*** |Black**** |"US" |Beige |
* 1st Design (very early 1956) ** 1st Design (very early 1956) Black mat is unverified *** 2nd Design (early 1956) & 3rd Design (1956-57) **** 2nd Design (early 1956) Black (or Beige) mat is unverified
Division Panel
The division panel is made of asphalt impregnated paper board containing a distinct .Spanish. grain, and is painted trunk color (refer to color charts at the rear of this manual). A “W” (within a circle) manufacturer’s identification logo should appear at the upper left-hand corner.
On all cars, regardless of whether or not the vehicle was equipped with a power top, the panel was notched for a safety switch on the left side in 1956 and the right side in late 1956 and 1957. Also, all 1956-57 division trim panels are bulged for power top equipment, even those vehicles not equipped.
Screws & Clips
The panel is normally attached at the sides with zinc-plated clutch-head screws and finishing washers, two per side; along the bottom with Phillips-head screws and finishing washers. Top edge of trim panel fits under body lip and may not be secured. The rear emblem is held in place with three army green colored speed nuts with rubber insulators.
19. TRUNK MAT, SPARE COVER & BOLT
Trunk Mat
Trunk mats will contain molded-in part number identification as shown in accompanying trunk mat chart. Normally, mat color is red for red interior trimmed models; black with beige trim combinations (see color charts at rear of this manual). However, a 1st design beige mat was probably used with beige interior trim on very early 1956 models (as described below). First design 1956 trunk mats are reworked 1954-55 red, beige, or black mats. Three areas were cut (by hand) for added clearance of the trunk latch, power top hydraulic cylinder, and the clip used to secure the jack handle. These 1st design mats are solid colored rubber and carry a “Baldwin” manufacturing logo.
At some unknown point in production, 2nd design 1956 mats were used which are similar to the 1st design, but were specifically molded to fit the 1956 trunk. These 2nd design mats carry a “US” symbol (within a circle) signifying the U.S. Royal Rubber Company. They are black rubber with a vinyl colored top skin. The red mat has been verified; however, a black (or beige) 2nd design mat is unverified. It’s likely that the 2nd design mat used with beige trim was black, as the initial 1956 Corvette color chart published by Chevrolet (refer to rear of this manual) specifies a black mat.
The common 3rd design red and black mats were used for the balance of 1956 production (starting point unknown), continuing through 1957. They are also of black rubber with a colored vinyl top skin and carry the “US” logo. This 3rd design has the same part number identification as the 2nd design, but utilized a large curved relief at the forward left edge for power top equipment. All 1956 and 1957 trunk mats incorporate the necessary relief clearance for power top equipment, even for those vehicles not so-equipped. Trunk mats are calendar year date coded.
Spare Wheel Cover & Bolt
The spare tire cover is made of construction grade 3/8" plywood, normally not showing knot repair plugs, containing five (5) laminated layers, stained with black transparent stain, grain showing through. Cover’s center stamped metal retainer is cadmium plated, unpainted, attached with three countersunk, slotted wood screws, and contains “G” manufacturer’s logo. Long center hold-down hex-head bolt which has no head markings, a tapered pointed end approximately ½” in length is cad plated.
Three foam rubber pads are cemented to underside of cover to cushion scissor jack when stored.
Label(s)
A jacking instruction sheet is cemented (stapled in early 1956) to the topside of the cover, generally on the left-hand surface between the center hold-down and trunk latch opening. The height of the thin line frame abound either of the jack drawings should be 4 3/16” high on an original label.
On 1957 manual transmission vehicles equipped with Positraction (RPO 677, 678, or 679), a limited slip differential “CAUTION” label (undated, which begins with the words “THIS CAR EQUIPPED...”) is glued to the spare cover, normally to the left of the jack instruction label, however, its early use and location may have varied.
20. JACK, HANDLE & LUG WRENCH
Jack
The Corvette “scissor” type jack uses a cast base (containing “SJ4653” identification), stamped arms, a lifting saddle with center radius dip, and is held together with solid roll pins with flattened ends. Jack center shaft contains fine threads. Jack and front bearing are painted semi-gloss black and is stored inside spare wheel hub.
Jack Handle
A folding jack handle (also semi-gloss black) is stored in a folded position on the right-hand side with the crank handle facing the right fender cavity, secured with a special metal clip. The folded pivot is inserted through a slot provided in the division trim panel. The end inserted into the jack has a tang resembling a spoon; not a hook with 90-degree bend. Rivet head holding the jack handle pieces together is round and the same size on both sides.
[pic]
Lug Wrench
The lug wrench (painted semi-gloss black) is stored in the left-hand side of the trunk, with the pointed wheel cover prying end inserted under a slot provided in the trunk division fiberboard trim panel. The lug end of the wheel wrench tool is secured with a special metal clip, with the wrench socket pointing toward the left inner fender cavity. The lug wrench was manufactured so as not to contact the division panel while removing or installing the spare tire cover retaining bolt. The length from the hex head to the bend is 4”. The bend to tapered end is 17 ¾”.
Stowage Clips
Several styles of lug wrench and jack handle hold-down metal spring clips were used. The 1st design 1956 tool clip (used for both wrench and jack handle) was riveted to the trunk deck; the 2nd design 1956 tool clip used bent position retaining tabs through two small holes in the trunk deck, each secured with a single Phillips screw, and was used through approximately 1957 serial number 4750; a 3rd design clip secured the lug wrench and attached with two Phillips screws, while the jack handle clip was J-shaped, attached with a single Phillips screw. Tool attaching clips and screws were in place when trunk was painted.
21. POWER FOLDING TOP EQUIPMENT
Hydraulic folding top equipment was available as an option (RPO 473). However, Chevrolet data indicates that early 1956 models through about March of 1956 production were initially not available without power top equipment.
Although not completely visible, an attempt should be made to verify electrical wiring, limit switches, hydraulic components, hydraulic lines and mounting brackets on vehicles so equipped. If a car appears without folding top equipment, the judge should attempt to deter-mine if the components have been removed. On 1957 power top cars, mounting plates are riveted to the underbody just behind the right hand door to secure a limit switch assembly. 1956 cars exhibit a double toggle switch on passenger side inside the soft top compartment. All cars have the plates in front of the spare tire well to secure the hydraulic pump and the deck lid ram. If these plates do not appear, inspect to determine if the rivet holes have been filled.
The control switch is mounted to the right of the hood release and has a black plastic knob with “TOP” in white letters. Even those without a power top will have the mounting holes for this switch. In 1956 the main wiring harness does not have in-line fuses, while in 1957 it has two in-line fuses at the control switch end. The single wire harness connectors are black, and the multi-connectors are black or opaque.
The 1956 top lid limit switches are located in the trunk. 1957 switches are in the top compartment and covered with a metal box. They were installed before trim painting, so the metal box is painted top compartment color.
The trunk lid safety switch is on the left side of the trunk for 1956; the right side for 1957. The top lid switch is mounted to the top of the seat separator with clutch head machine screws. The safety switch brackets were installed prior to painting and will appear with trim color. Hydraulic lift cylinders are located behind each seat and in the trunk. The hydraulic hoses in the top compartment are held down with special clips on each side.
The following items were installed prior to trim painting and may appear with varying degrees of overspray: wire harnesses, limit switches, limit switch covers in top compartment (1957 only), and safety switch brackets.
A full deduction is appropriate for vehicles with evidence of power top equipment removal. Full credit should be given for those vehicles legitimately not so equipped.
22. OVERALL CLEANLINESS
Do not deduct for dust or occasional lint. Purpose of this item is to verify the owner has cleaned the interior to a level typical of new car delivery.
EXTERIOR SECTION
1. BODY COLOR
Body Color
Refer to Chevrolet’s 1956 & 1957 Corvette Color Charts, which accompany this judging manual, for specified exterior body color combinations. Exceptions can be made only with thorough factory (not dealer!) documentation (examples: white body with red fender-door cove depression). The side panel cove depression is painted either body color or in contrasting two-tone color to harmonize with overall appearance, as per color chart.
Auxiliary hardtop (if equipped) must be in body color, not cove color. Any undocumented deviation regarding change of specified hardtop or cove color from color charts is subject to full point deduction.
2. BODY PAINT
Body Paint
All exteriors were painted with DuPont “Duco” nitro-cellulose lacquer, except 1957 Inca Silver body paint, and its optional two-tone Imperial Ivory fender-door depression, which are DuPont “Lucite” acrylic lacquer.
1957 Corvettes with Inca Silver (and two-tone Imperial Ivory fender-door depression) should have a paint caution paper label cemented to the right-hand side of the firewall, above the heater opening in the engine compartment.
Up to full deduction of originality points should be made if use of enamel paint or clear-coating is obvious. Partial deductions on originality are appropriate for excessive orange-peel (do not deduct for reasonable orange-peel), paint surface roughness, and for paint overspray on trim moldings. Deduct on condition for excessive chips, paint cracks, scratches, and fading.
3. CONDITION OF FIBERGLASS & FIT
Fiberglass & Fit
Factory component fit may be less than perfect. Some panel waviness is normal. Point deductions are appropriate for obvious poor panel fit, panel separation, cracks in fiberglass, and poor repairs. Also, point deductions are appropriate for obvious over-restoration. Check in this section for presence of the molded fiberglass ridge surrounding the upper portion of the trunk lock.
Note: Full deduction of condition points is appropriate if body has any custom fiberglass modifications.
4. TOP
4A. HARDTOP
Exterior Moldings
Generally, the 1956 hardtop has a 1" wide aluminum front header. This front header may have been painted exterior body color on early 1956 vehicles. Near 1957 model change the front header was covered by a 2" (approximate) wide bright stainless molding (2-piece, left and right, with center escutcheon).
The rear window lower stainless reveal molding is three-piece, using a Y-shaped escutcheon at the end of the roof side drip molding, both left and right. Trailing edge of side rain gutter contains a sharp edge, not a rounded edge.
Deductions are appropriate for “pop” rivets used to replace metal trim moldings.
Rear Window
Hardtop rear window is acrylic plastic (Plexiglas). Window contains “PLEXIGLAS” logo stamping,
”AS-4” (rating), and is date coded (example: “7 6” would indicate July, 1956). It is generally believed that rear windows were basically rectangular in shape, with a slight outward taper, top to bottom, with all four corners having a similar radius. Use Standard Deduction Tables for awarding originality points regarding hardtop rear window dating. Plexiglas windows should be free of scratches, cracks and hazing.
Side Windows
Hardtop side quarter windows are acrylic plastic (Plexiglas). Windows contain “PLEXIGLAS” logo stamping, “AS-4” (rating), and are each date coded (example: “7 6” would indicate July, 1956). Use Standard Deduction Tables for awarding originality points regarding hardtop side window dating. Plexiglas windows should be free of scratches, cracks and hazing.
Weatherstrip, Window Channel & Side Window Seals
Side door window rubber weatherstripping is black cloth-covered. Check front header seal, also check for splits in heat-molded seams used with one-piece deck lid/window seal assembly. Deductions are appropriate for “pop” rivets used to replace side window weatherstripping.
4B. SOFT TOP
Color & Material
Nylon soft tops were available in three colors; White, Black or Beige. Refer to the color charts at the rear of this manual for available soft top color combinations. Top material is “diamond” grain.
Stitching & Bindings
Exterior “hide-em” welt binding at bow above rear window is secured with bright stainless steel tips with no rolled edge, attached with one small oval-head phillips screw. Length from rolled edge to top of seam is approximately 7 to 7 ½”. Hide-em welt and top bindings are the same color as soft top material but the diamond pattern is less pronounced. Soft top side seams are sewn, not hot-sealed.
Rear Window
The convertible top rear window is made of vinyl plastic and is sewn (not heat-sealed) into soft top. Original rear window normally contains a “VINYLITE” trademark, “AS-6” (rating), a manufacturing date code (example: “3 7” indicates March, 1957), and window washing instructions, hot-stamped into the lower left corner of the plastic window. Rear windows were basically rectangular in shape with a slight outward taper, top to bottom with all four corners having a similar radius. [pic]
Warning Label
Also, a rear window cleaning tag was sewn (with single-pass stitching) in the extreme lower left corner of the top. The tag will show an inspectors punch symbol (similar to the carburetor brass tag) and a circular stamped ink impression on the back side. Convertible window should be clear without scratches or hazing.
| | |1956-1957 LOF GLASS CODES | | |
| | | MONTH | |YEAR |
|January |N | |May |J |September | |F |1955 |X |
|February |M | |June |I |October | |E |1956 |V |
|March |L | |July |H |November | |C |1957 |T |
|April |K | |August |T |December | |V | | |
5. WINDSHIELD GLASS & TRIM
Windshield Glass
Glass is laminated LOF Safely-Plate brand; clear, not tinted. Refer to Standard Deduction Tables for awarding originality points. Deductions on condition are appropriate for cracks, excessive pitting, or wiper blade scratches. Glass is date-coded as per accompanying chart.
Frame & Gasket
The windshield side posts are chrome plated; the lower reveal molding and header molding are polished stainless. Glass is framed by a black rubber channel gasket seal.
[pic]
6. SIDE DOOR GLASS & METAL SURROUND
Side Door Glass
Laminated side door glass is framed in bright metal. Refer to Standard Deduction Table for awarding originality points for door glass. Side glass is date-coded LOF Safety-Plate brand and is clear, not tinted. Deductions on condition are appropriate for cracks or excessive pitting or scratches. Glass date codes are presented on previous page.
7. COWL VENTILATOR & WIPERS
Cowl Vent
The cowl vent and screen are painted body color, with an unpainted continuous non-spliced black foam rubber seal cemented to the body.
Wiper Arms, Bezels & Gaskets
Windshield wiper arms are spring-loaded, Trico brand. Trico blade holders are metal four-bar type, with black tips at each end. Metal is polished. Wiper transmission chrome escutcheon seals to body with a black rubber gasket.
Wiper Blades
Non-replaceable rubber blades have a series of raised dots down each side along with patent pending and number molded into the rubber blade. Rubber end tips will also be seen.
Washer Nozzles
Windshield washer spray nozzles (if equipped) are chrome plated, pointing to centerline of vehicle, parallel with rear edge of cowl vent door. Nozzles seal to body with black rubber washers.
8. FRONT, REAR & SIDE EMBLEMS
Front Emblems
Colorful “Chevrolet Corvette” plastic emblems with chrome bezels and a gold Vee beneath the crossed flags mount on the front of all vehicles. Emblem is attached with flat rectangular speed nuts.
Side Emblems
On fuel injected 1957 models, “Fuel Injection” block letter script is located on the side fenders, to the rear of separate, painted chrome metal crossed flag emblems. FI script is also located on the trunk, about 1" above the Corvette emblem. The FI script is chrome, with black paint separating the words “Fuel” and “Injection”. FI script is not used on the front.
No side emblems whatsoever appear on the side fenders of carbureted models.
Rear Emblems
Colorful “Chevrolet Corvette” plastic emblems with chrome bezels and a gold Vee beneath the crossed flags mount on the trunk of all vehicles.
9. FUEL FILLER AREA & GAS CAP
Filler Area Paint
Gasoline filler door area is painted exterior body color
Rubber Items & Clips
Filler pipe, black rubber pipe grommet and gas cap are normally unpainted. Door bumpers are installed with horizontal “shelf” at the top and were in-stalled prior to painting.
A fuel tank vent rubber hose, vent hose grommet, and metal hose retaining clip were added during 1957 production, approximately serial number l425. This vent may appear with paint overspray. Also, this vent may have been dealer retrofitted on earlier vehicles, and a moderate deduction is appropriate.
Vehicles with vent hose should have a non-vented gas cap. The fuel filler area also has a 5/8” hole to drain fuel spilled in the filler area. [pic]
Gas Cap
Gas caps are plated, and appear as illustrated:
[pic]
Vented Non-vented
1956 to early 1957 early 1957 & later
10. GRILLE ASSEMBLY & RADIATOR FRONTAL AREA
Grille Frame, Center Bar, Grille & Teeth
[pic]
Grille frame, center horizontal bar, and 13 teeth are bright chrome plated. Teeth are symmetrically arranged outboard from center, with three outer teeth each progressively smaller than the seven center-most teeth (refer to illustration).
Service replacement teeth may show a “nose” less pointed than original. Five stamped-steel semi-gloss black painted vertical support brackets are used to attach the bright bar and teeth assembly to the grille frame. Point deductions are appropriate for grille frame fit misalignment if body panel cutouts are exposed. Check for pitting of pot-metal frame and teeth.
Front Radiator Area
Frontal radiator skirt body panel area behind grille is painted in black-out, same as engine compartment.
Horns
Left and right Delco-Remy horns are domed type (referred to as “sea-shell” type by Chevrolet) on 1956 through early-1957; horns changed to different, solenoid type in early 1957. Right-hand horn is low note; left-hand high note. Horns are painted gloss black.
11. FRONT BUMPER AREA
Front Bumpers
Right and left front horizontal chrome “crescent” bumpers are elliptical in section and fit snugly against fenders.
[pic]
1956 through early 1957 horns are domed “sea shell” type as illustrated at left; remainder of 1957 used solenoid type horns, as shown at right.
Vertical Bumper Guards
1956-57 vertical bumpers are different from 1955 variety in that they contain a radius curve following contour of lower body panel.
License Plate Holder
Bright chrome license plate bar is attached between two vertical chrome bumpers with indented hex head machine screws. Bar is channel-shaped, and contains “Guide” Division logo stamping at the rear center.
Verticle Bumper Support Brackets
Vertical bumpers are mounted with 5/16" round head zinc plated carriage bolts to semi-gloss black tubular supports attached to the front chassis crossmember; rearward with single bolts, forward with bolts and U-shaped brackets.
12. HEADLAMP ASSEMBLIES
Headlamps
Headlamp bulbs must be matching Guide T-3 design; with pebble-grain (not vertical ribs) within triangle. 1956 bulbs use 3/8” high lettering on SEALD BEAM and 1957 use ¼” high lettering. Some overlapping of usage may occur at model year change. Use Standard Deduction Table for awarding originality points for bulbs.
Lamp Bezels
Very early 1956 Corvettes to approximately serial 1360 have chrome headlamp door bezels over-painted exterior body color. From serial number 1360 to approximately 1600, headlamp doors may be either painted or unpainted chrome in matching sets. Remainder of 1956 production through 1957 use chrome doors exclusively. Headlamp door bezels are attached with slotted-head screws. There is a gasket between the headlamp and bezel.
13. PARKING LAMPS
Parking Lamps
Park lamp assemblies are sealed to exterior of body with thick black rubber gasket. Lamp lenses are glass, and contain “F-57” designation. Lamp’s inner bulb is clear, not amber. Lenses are sealed to the park lame assemblies with unpainted cork gaskets.
Bright metal lamp door bezel is early “curved-shoulder” design, except for late-1957 (after approximately serial number 5000), which may use later “square-shoulder” type. Each lamp door bezel is attached with two zinc plated slotted-head barrel screws.
14. BODY SIDE TRIM & MOULDINGS
Moldings
Each front fender and door cove body depression is outlined by a narrow bright stainless molding which continues over the front wheel opening to the front bumper. The fender upper molding is two-piece, with the forward piece attached by two pan-head slotted screws (pan-head Phillips may also have been used). Cove moldings should be dent-free.
Air Scoop
A simulated air scoop with bright metal grille is located on the crown of each fender, just forward of the windshield.
Door Handles & Locks
Chrome plated push-button type door opening handles are mounted to each door with rubber gaskets. A key lock is mounted below each push-button release. Door handles should be checked to ensure that they do not WING UP due to the base under the push button being too thick.
15. REAR BUMPER AREA
Vertical Bumpers
Two vertical chrome bumpers follow the contour of the rear fenders, with chrome tailpipe bezel projections, directing exhaust away from body.
Horizontal Bumper/License Plate Light
Horizontal chrome bumper bars containing a separate chrome license plate lamp, flank the center license plate bracket, ending just short of either fender. These horizontal bars attach to the body through rubber pads, which are unpainted. License plate light should be directed at the license plate, not in the upper direction. License lamp wires pass through the body via un-painted black rubber grommets
Tail Lamps
Recessed chrome plated tail lamp housings mount at the rear crown of each fender (a large chrome countersunk Phillips screw is used to attach the rear portion of the housing to the body). The red plastic conical taillight lens is surrounded by a narrow red reflex band, and the lens is attached to the housing with pan-head slotted machine screws. Each housing seals to the body with a black rubber gasket, which is not detectable. The housings are pot-metal; check for pitting.
Trunk Lock
Bright metal trunk lock and escutcheon are mounted below the Corvette emblem.
Rear License Plate Bracket
Bracket is painted gloss black and contains a 9/16" diameter black rubber bumper. The bracket is stamped with part number identification, “Chev 371166”. It’s fastened to the rear center of the body below the trunk with two plated hex head bolts and one spacer at the lower position, with the license plate attaching bar at the top.
16. RADIO ANTENNA
Exterior Mounting
Antenna mast is telescoping three-piece design and is mounted on the crown of the left rear fender, just ahead of the taillamp housing. The mounting nut and spacer are knurled black plastic. The mirror ball and shaft are carbon steel, not stainless.
Interior Mounting
The antenna base mounts in the trunk fender cavity with a sheet metal bracket, and a grounding strap is connected from the bracket to the lower body/frame mounting bolt. Antenna should have no signs of trunk paint overspray.
Full credit can be given if vehicle shows no signs of being radio equipped.
17. EXTERIOR REAR VIEW MIRROR
Exterior Mirror
Mirror is Guide Y-50 type and head is so-stamped. Glass is non-replaceable shaded type, and does not contain a date code or manufacturers ID. Mirror is a left-hand model in that Allen-head pedestal attaching screw mounts from cockpit side. Mirror pedestal base bracket attaches to left door with black sealing pad. No mirror is used on the right-hand door.
18. WHEELS (including spare)
Wheels
Wheels are painted body color (enamel) on the face; except for Polo White cars using red wheels with red interior trim (1956-57), silver wheels with beige trim (1957). Refer to color charts at rear of this manual. Rim face is fully painted; center hub may not be completely covered, but rather oversprayed. Backside of wheel painted black, but will show signs of face color overspray.
Correct wheels have a hub containing a distinct double outer ridge, three nubs used for small hub cap attachment, and unpainted black rubber tubing stone seals are inserted into rim slots between hub (which are not visible with wheelcover installed). Standard wheels are 15x5"; optional 1957 wheels (RPO 276) are 15x5-1/2". Generally, metal valve stem caps were used. Spare wheel installs face down in spare tire well so that scissor jack can be stored inside wheel hub.
Generally standard wheels are welded and 5 ½” wheels are riveted. Riveted wheels do not contain the four nubs to attach the standard full wheel cover. All wheel weights were installed on the inside of the wheel. Weights should not indicate any metric weight designation. Wide base wheels, RPO 276, are a required option for RPO 684. Factory records indicate fifty-one sets of wheels were ordered, one set retained in engineering, forty-eight used on RPO 684 cars, and two sets unaccounted for (perhaps to help out dealer-backed race teams). Without further documentation to indicate otherwise, RPO 276 wide wheels are correct for RPO 684 cars, which were only available after serial number 3700.
19. WHEELCOVERS
Wheelcovers or Hubcaps
Full wheelcovers are bright polished stainless steel, with spoke-like radial embossments surrounding the hub area.
A circular depression, behind the center ornament, has a brushed finish to contrast the bright ornament. 1956-57 full wheelcovers do not contain open vent slots as later Corvettes use.
During 1957, wide-base (15x5-1/2") wheels became available as an option (RPO 276). Corvettes equipped with these wider wheels use small hub caps, identical to those used on 1957 Chevrolet model 150 and 210 passenger cars.
Ornaments
A chrome plated simulated knock-off ornament with black crossed flags and words “Chevrolet Corvette” on a brushed circular plaque is mounted in the center hub, with words readable when tire valve stem opening is down. Original ornaments appear with a molded line, or ridge, on the outer ends of the spinners.
20. TIRES (including spare)
Tires
Use Standard Deduction Table for awarding originality points. Full originality points can be awarded only for matching 6.70xl5" tires of OEM brand and grade. Original tires used are U.S. Royal “Air Ride”, B.F. Goodrich “Silvertown”, and Firestone “Deluxe Champion”. Whitewall width (if so-equipped) varies from 2" to about 2-3/4"; wider whitewall widths appear to have been used in earlier production. Original tires did not contain DOT markings.
21. UNDERBODY & WHEELHOUSES
Underbody
The underside of the body floor-pan assembly is not painted, but may show signs of overspray, especially on spare tire well.
Wheelhouses
Wheelhouses received black-out paint and some degree of stone protective undercoating; quality and amounts vary. Rear of headlamp assemblies and metal splash pans were sprayed. Headlamp wiring is housed in a black woven fabric tube referred as Auto Loom. Parking lamp wiring is housed in a ½” OD black rubber tube. Both tubes are attached to the front inner fender panel by a single metal “J” clamp.
Splash Pans
1956 models use one-piece metal splash pan to the rear of each front wheel; 1957 uses two-piece splash pans. Pans assemble (if applicable) and attach to the body with 1/4-20 clutch head machine screws and fasten to the frame with recessed hex head sheet metal screws. Front splash pans use rubber seals between the pan and fender. Splash pans and seals were installed prior to undercoating and will appear with overspray. Deductions are appropriate for excessive accumulation of dirt, grease and oil on underbody.
[pic]
1956 Corvettes use a single splash pan plate behind each front wheel; 1957 is a two piece assembly, using additional “tail” extension as illustrated.
22. Overall Cleanliness
Overall Cleanliness
Do not deduct for dust or minor traces of wax or polish residue. Purpose of this judging entry is to verify that the owner has cleaned the exterior surfaces to a level typical of new car delivery.
MECHANICAL SECTION
1. ENGINE COLOR
Judging Instructions: Judge only the originality and condition of the engine orange paint application on all components here. Do not re-judge engine paint; i.e., water pump, oil pan etc..
Engine Color
1956 Corvette engine color is red except possibly the last few weeks of production, which may be orange; 1957 engines are painted orange.
Exhaust manifolds, bellhousing, with throw-out arm, and the two lower dust covers on manual transmission equipped motors were in place at the time of painting and will appear with differing degrees of engine paint. Application was brisk; coverage varied and runs occurred. It is generally believed that the engine stamp pad was wiped with solvent after painting and may appear with remnants of engine color in the stamped characters.
2. ENGINE BLOCK
(Use Standard Deduction Table to award originality points)
Engine Block Casting Numbers
Engine Block Casting Numbers
1956 (265 cubic inches).........3720991
1957 (283 cubic inches).........3731548
The engine casting number is located on the top left surface of the flange formed at the rear of
the block for bellhousing/transmission attachment.
Some engine block casting numbers may contain an “X” character, which is a Central Foundry
casting proofmark to alert the Flint machine shop that the block is from an initial casting run.
Engine Block Casting Date
The casting date is located at the right rear, top portion of the bellhousing or transmission mounting flange (opposite the casting number). Casting dates begin with the letter “A” for January, ”B” for February, and so-on (the letter “I” representing the month of September is used) through “L” for December; digit, or digits, representing the date of the month (“1” through followed by a 1"31"), followed by a single digit representing the calendar year (“5” for 1955, “6” for 1956, or “7” for I957). Engines appearing with two-digit year casting date codes (“55”, “56” or “57”) indicate manufacture at Tonawanda, not Flint, and should not be considered correct for 1956-57 Corvette applications.
| |CYLINDER CASE CASTING CODES BY MONTH |
|A |January |D |April |G |July |J |October |
|B |February |E |May |H |August |K |November |
|C |March |F |June |I |September |L |December |
| | | ENGINE PAD IDENTIFICATION SUFFIX |
|YEAR |CODE |H.P. |EQUIPMENT |
|1956 |FK |210 |1x4 BC & Powerglide Transmission |
|1956 |GV |210 |1x4 BC & 3 speed Transmission |
|1956 |FG |225 |2x4 BC & Powerglide Transmission |
|1956 |GR |225 |2x4 BC & 3 speed Transmission |
|1956 |GU |240 |2x4 BC, Hi-Lift Cam & 3 speed Transmission |
|1957 |EF |220 |1x4 BC & 3 or 4 speed Transmission |
|1957 |FH |220 |1x4 BC & Powerglide Transmission |
|1957 |EH |245 |2x4 BC & 3 or 4 speed Transmission |
|1957 |FG |245 |2x4 BC & Powerglide Transmission |
|1957 |EM |250 |Fuel Injection & 3 or 4 speed Transmission |
|1957 |FK |250 |Fuel Injection & Powerglide Transmission |
|1957 |EG |270 |2x4 BC, Hi-Lift Cam & 3 or 4 speed Transmission |
|1957 |EL |283 |FI, Hi-Lift Cam & 3 or 4 speed Transmission |
EN*.....283.....FI, Air Box, Hi-Lift Cam & 3 or 4 Speed
* Existence of “EN” block is unverified, RPO 579E equipped cars may have been supplied with “EL” coded engines.
Assembly Identification Stamping
The engine assembly identification stamping is located on a boss at the right front top of the block, on a pad just forward of the cylinder head. A character resembling the letter “I” was used to represent the digit “1”.
1956-57 Corvette V-8 engines were cast at Saginaw, Michigan; machined and assembled at Flint, Michigan.
1956 engines were serial numbered in sequence starting with 0001001. There is no correlation between the engine serial number and the vehicle serial number other than higher serial numbered cars tend to have higher serial numbered engines. 1956 engines are stamped with four individual strikes to the pad. The first five sequential numbers are in one holder; the following two strikes are individually hit resulting in a somewhat misplaced appearance. The final suffix code F56?? is stamped in a five-character holder. Thus engine stamps will always appear in a 5-1-1-5 sequence. The engine serial number was followed by the letter “F” (for Flint), “56” (the model year), and then the suffix code letters designating the type of engine, as shown in the accompanying chart. The 1956 engine block casting date must precede the theoretical vehicle assembly date, generally from four to eight weeks; however, refer to Standard Deductible Tables for awarding originality points to engine blocks.
1957 engines eliminated the use of a continuous engine serial number. The 1957 engine stamps used a five digit holder for the suffix only and when a sixth digit was required it was struck individually. The 1957 stamping began with the letter “F” (Flint), followed by one or two digits indicating the month of engine assembly (“1” for January through “12” for December), then two digits signifying the date of the month (“01” through “31”), ending with the suffix identification code as shown. Refer to Standard Deduction Tables for awarding originality points to engine blocks.
Stamp Pad Surface Finish
When inspecting the block identification stamping(s), check for lengthwise broach marks on pad surface, as well as around edges where the cylinder heads mate to block. Appearance of circular or other machine marks are an indication of block resurfacing and restamping.
Full point deduction is appropriate if paint or dirt and grease buildup prevents reading of casting number, casting date, or identification stamping; or if casting number is incorrect.
3. CYLINDER HEADS
Cylinder Heads
With valve covers installed, cylinder head identification is by casting symbols located at each end. Also, 1956-57 heads use only staggered tapped holes (as illustrated) for attaching valve covers. (Note: Valve covers are to be judged as a separate item.)
[pic]
Cylinder Head Casting Symbols, Numbers, & Applications
Symbol Year Casting # Application
[pic]
1956 3725306 All 210 & early 225 HP w/2-bolt Exh. Manifolds
1956 3731762* Later 225 & 240 HP w/3-bolt Exh. Manifolds
1957 3740997 All 220, 245, 250, & 270 HP
1957 3731539 All 283 HP
* Some carryover into early 1957 production occurred
Although not visible for judging purposes, the following cylinder head information may be useful, and is therefore provided: The V-8 cylinder head casting number is located between the #5 and #7 or the #2 and #4 valves, depending on which side of the block the head is mounted (heads are interchangeable), and is only visible with the valve rocker cover removed. The cylinder head casting date is located in the valve rocker area (next to the #1 and #3 or the #6 and #8 valves, depending on which side the head is mounted) and is visible only with the valve cover removed. The casting date for the cylinder heads is deciphered in the same manner as that described for the engine blocks. Cylinder heads were cast at Central Foundry Division at Saginaw, and machined and assembled to the engine block at Flint. Some casting numbers may contain an “X” character, which is a Central Foundry casting proofmark to alert the Flint machine shop that the part is from an initial casting run.
4. VALVE COVERS
Valve Covers
All cylinder head valve covers (as described below) use staggered mounting holes (as illustrated for cylinder heads).
Standard engine stamped steel valve covers attach to the head by Phillips screws and special washers, both painted engine color. Optional engine cast aluminum covers attach with unpainted zinc-plated Phillips screws without washers.
It is believed that 1956-57 valve covers did not use engine horsepower decals.
1956
Standard 210 HP: Valve covers are of stamped steel with raised “Chevrolet” script. The cover and Phillips attaching screws with special washers are painted engine color. The script is highlighted in silver paint.
Optional, early 225 HP with 2-bolt flange exhaust manifold and “pyramid” symbol heads: Covers are of die-cast aluminum (unpainted) with nine longitudinal ribs on top. The ribs are spaced to allow for the word “Corvette” in low-relief in the center. Valve covers used with 3738725 intake manifolds were not notched for clearance around the intake runners until approximately serial number 1650. Intake manifolds with casting number 3731394 replaced the 3738725 manifold on later 225 and 240 hp engines and their larger runners necessitated two clearance notches at the top of each cover.
Optional, later 225 & 240 HP with 3-bolt exhaust flange & “twin-tower” symbol heads: Same as early 225 HP covers, except two notches are added to the inboard mounting lip, for intake manifold clearance (starting approximately serial number 1650).
1957
Standard 220HP: Covers are stamped steel with raised “Chevrolet” script, attached with Phillips screws and special washers, all painted engine color. The script may, or may not, be high-lighted in silver.
Optional Engines: At the beginning of production, cars equipped with dual four barrel carburetion or fuel injection used notched 9 rib, cast aluminum covers with low script “Corvette” identification. As indicated in the following table, some fuel injected models have one (or possibly both) covers machine notched in the center to alleviate air meter interference. Later in production, a changeover to a similar design, 7 rib cover occurred.
|VALVE COVER USAGE |
|Dual 4 Barrels |Fuel Injection |
|0001-3900 |9 rib |0001-1900 |9 rib |
|3900-4500 |9 or 7 rib |1900-2900 |9ribw/cut |
|4500-End |7 rib |2900-End |7 rib |
Gaskets, Screws, Washers & Clips
Gaskets are tan cork composition. An engine temperature gauge sensor wire (judged in item #17) is loom routed along the inboard side of one valve cover; left-hand on standard engines, right-hand on optional engines. The wire loom is retained to the cover with special clips; spot-welded to stamped covers (thus painted engine color), or cadmium plated clips retained under both inboard mounting screws on cast covers.
5. AIR CLEANER ASSEMBLY
Carbureted Air Filter
Base engine single four-barrel equipped models use 11" diameter chrome air cleaner with four rows of louvers. The air filter is not serviceable, and the underside contains a stamped depression to clear the carburetor thermostatic choke housing. Dual four-barrel models use a pair of 6-3/4" diameter aluminum units. Some 1957’s equipped with a single four-barrel carburetor may have used a single 6-3/4" diameter dual-four carburetor type aluminum air cleaner, but usage is unverified. Air cleaners are held down with low-profile, plated, stamped steel wing nuts.
Fuel Injection Air Cleaner
Fuel injected 1957.s initially used a one-piece sealed air cleaner with louvers. Later 1957 uses a two-piece chrome air cleaner with replaceable type open filter element with AC stamped into the blue rubber end seal. The lid has a 2” square mesh which is spot welded to the base, held in place with a flat washer and a solid cast wing nut.
1957 RPO 579E Corvette with outside air intake uses hand-laid fiberglass box mounted to left inner fender skirt. Internal filter element is accessible through a fiberglass cover attached to the box with clutch-head screws. Fresh air is routed to FI air meter by fabric-covered 4" duct hose.
6. FUEL SYSTEM & INTAKE MANIFOLD
Carburetors
All carburetors attach to the intake manifold with studs and hex nuts without lock washers. All carburetors will appear with cadmium plated linkage on natural brass shafts. Air horns are natural aluminum. Main body and choke housings have a pale gold tone irradiate finish. Cast iron bases will have a thin black preservation paint.
1956 single four-barrel carburetor (2366SA) did not use any auxiliary air valve assembly. The choke bakelite cover is flat, with hot air for warm-up entering from rear of housing, through an externally threaded protrusion. Primary venturi is 1-1/16", secondary 15/16", cast between bores. The air horn is casting number 6-1098 (early) or 6-1151 (late); main body is cast 0-953. 3266S air horn casting 6-1098 has narrow choke housing mounting boss and narrow boss on housing. 3266SA air horn casting 6-1151 has narrow choke housing mounting boss and narrow boss on housing.
1957 single four-barrel carburetor (2655S) uses an auxiliary air valve assembly with lever and weight overall length of 1-31/32"; weight diameter is 13/16" (1/4" thick on early, 1/2" thick on later). The choke bakelite cover has hot air threaded nipple protruding from center, however unthreaded rear casting protrusion used on previous carburetor is still present, but unused. The primary venturi is cast “1” (for one inch) between the bores. The air horn is casting number 6-1271; the main body is cast 0-108 (some possibly 0-1108). It is doubtful that 2366SA carburetors were used in 1957 because the choke housing cover and hot air tube differed from 1957
| | CARBURETOR CASTING NUMBERS |
|YEAR |MODEL |MAIN BODY |AIR HORN |
|1956 |2366SA |0-953 |6-1098 (early) |
| | | |6-1151(late) |
|1957 |2655S |0-108 or 0-1108 |6-1271 |
|1956 & early '57 |2419S Front |0-049 |6-1114 early |
| | | |6-1122 early |
| | | |6-1151 late |
| | | |6-1203 very late '56 & |
| | | |early 1956 |
| | | |6-1156 very late '56 & |
| | | |early 1957 |
|1956 & early '57 |2362S Rear |0-049 | |
|1957 |2626S Front |0-049 |6-1203 or 6-1299 |
|1957 |2627S Rear |0-049 |6-1203 or 6-1299 |
|Intake Manifold Casting Numbers & Carburetors |
|Year |HP |Manifold |WCFB Model |
|1956 |210 |3735448 3837109 |2366SA |
| | | |2366SA |
|1956 |225 |3728725 |2419S (front) |
| | | |2362S (rear) |
|1956 |225 240 |3731394** |2419S (front) |
| | | |2362S (rear) |
|1957 |220 |3731398 |2655S |
|1957 |245 |3739653 |2419S (front)* |
| | | |2362S (rear)* |
| | | |2626S (front)** |
| | | |2627S (rear)** |
|1957 |270 |3739653 |2626S (front) |
| | | |2627S (rear) |
* 1st design ** 2nd design
2655S design. Some 2655S carburetors used 6-1299 air horn. These did not have a stamped number near the casting number. 2655S carburetors had a vacuum advance provision on the throttle body front that was filled with a plug.
All dual four-barrel carburetors described below use a bakelite choke cover with embossed number 238S.
1956 dual four-barrel carburetors (2419S & 2362S) use auxiliary air valve assemblies with levers and weights measuring 1-13/32" overall; weight 13/16" diameter, 1/4" thick. Both carbs use idle air screw on left rear side of base plate. The air horn casting numbers are 6-1114 or 6-1122 (early), 6-1151 or 6-1203 (very late) and 6-1156 (very late); the main bodies are cast 0-049; all venturis are cast 15/16 between primary bores. Early air horns had a narrow casting boss where the choke shaft passes through, while later 1956 had a wider, beefier casting for choke shaft and mounting boss. The air horns that used a wider choke boss were 6-1151, 6-1156, and 6-1203. The last known use of 6-1151 was in August, 1956 carburetor production. Some late 1956 bases were cast 1-1387B using “air screw”. Base casting numbers are not visible with carburetor assembled. Front carb uses no choke or fast idle mechanism; rear carb choke bakelite cover is flat, with warm air tube entering rear of choke housing, same as 2366SA carburetor.
Early 1957 245 horsepower dual four-barrel carburetors are same as 1956, using idle air screws. In October of 1956, second design 1957 (2626S & 2627S) were introduced, which did not use idle air screws. (Original tag 2626SK6). It is likely to see some 2419S, 2362S and the 2626S, 2627S carburetors in November. Both use short auxiliary air valve levers and weights with overall lengths of 1-13/32", and ¼” (actually “290”) weight initially and through January, 1957. Sometime in February 1957 the front 2626S carburetor used the ½” thick weight, while the rear used the 1/4.. Sometime in March or April, 1957 both carburetors used the ½” weight and continued through the 1957 production. 1957 Air horn casting 6-1151 is possible but not likely. 6-1156 and 6-1203 were used on 1956 style carburetors and early 2626S and 2627S until about November 1956 when the 6-1200 casting started showing up. 2626S and 2627S bases are all cast 1-1387B without idle air screws. Main body castings are 0-049, however some with 0-1049, which May be original, have been noted, but not documented.
270 horsepower dual four-barrel cars most likely used 2626S and 2627S carburetors in 1957 as we have NO documention (original tags) that 2613S and 2614S were used prior to January of 1958.
ID Tags
The Carter WCFB carburetor model number will appear on a triangular brass identification tag attached to the air horn. This tag will also contain a manufacturing date code (.A. for January, "B” for February, and so-on) followed by the year (“5” for 1955; “6” for 1956, or “7” for 1957), and a single number indicating the Carter assembly line producing the unit.
Intake Manifold
Single four-barrel carburetor intake manifolds are cast iron (painted engine color), and carry the casting number and a casting date (as described for the engine blocks) on top of the manifold. Aluminum dual four-barrel carburetor intake manifolds (unpainted) carry a “snowflake” symbol with the letter “W” (indicating manufacture by the Winters Aluminum Casting Company of Dayton, Ohio, an outside vendor) and the casting number (with non-visible casting date) between the carburetor mounting bosses.
Thermostat Housing
Cast iron thermostat housing (.curved. design, # 3706018) is used with cast iron intake manifold on single four-barrel carburetor equipped models, painted engine color, and is attached with bolts. All 1956 and 1957 until serial number 2000 used a cast iron housing containing part number 3705018. 1957 after serial number 2000 aluminum intake manifolds used with dual-four carburetors use an aluminum thermostat housing, part number 3837223, attached with nuts to studs in manifold without washers. Intake gasket will have a small half-round ear visible on the upper edge near the manifold heat crossover passage.
Fuel Injection Unit
Rochester fuel injection units have an identification tag riveted to the forward left side of the plenum; except for approximately the first 100 model 7014360 units, which were hand-stamped with a serial number. Serial numbers started 1001, 1002, 1003, and so on. Note: Air and fuel meter numbers listed are stamped part numbers, not casting numbers; () indicates numbers omitted on various units. Vehicle serial numbers and FI unit serial numbers are approximate. Air meters and fuel meters will also contain a stamped component serial number (1001, 1002, 1003 and so on). There is no relation whatsoever to unit serial numbers, component serial numbers, and vehicle identification numbers. Model 7014960 is a recalibrated 7014800 unit. Also, FI model 7014800R (“R” means recalibrated) is a unit made from model 7014520, and may have appeared on some very late production 1957 Corvettes.
| | |1957 Fuel Injection Usage | | |
|Vehicle Serial# |HP | |FI Model |FI Serial* | |Air Meter |Fuel Meter |
|500-3000 |All | |7014360 |1001-1604 | |7014361 |7014362 |
|2500-4900 |All | |7014520 |1001-2060 | |7014521 |7014522 |
|3500-6339 |250** | |7014800 |1001-2623 | |(7014)801 |(7014)802 |
|4500-6339 |283 | |7014960 |1001-1326 | |(7014)801 |(7014)962 |
*Higher serialized units have been identified in the field
** Some late 283 horsepower engines possible
IMPORTANT NOTE: The chart is an attempt to establish a relationship of vehicle serial numbers to FI model and component numbers, as they left the St. Louis Corvette assembly plant. However, initially, field adjustments and repairs of faulty units was expressly prohibited due to inadequate dealer repair training and test equipment. Therefore, the policy regarding vehicle warranty problems relating to FI unit failure dictated that units were to be returned to Rochester, intact, for factory repair, complete replacement, or partial replacement, with newer, updated 1957 components. Later, this policy was changed to allow subassembly (air or fuel meter) substitution at the dealer level. 1957 fuel injected Corvettes that may have been subjected to factory warranty service may appear with factory substituted units or subassemblies appearing on the accompanying chart. Also, factory repairs may have involved the restamping, or overstamping, of subassembly component part numbers.
FI drive cable is connected to distributor with a very thick hex nut (as opposed to thinner 1958 style). An aluminum identification/inspection triangular tag is attached at the 10 o’clock position to the fuel meter at the enrichment diaphragm cover. Intake manifold contains casting number 3741193 for 4360 & 4520 units; 3748947 for 4800 & 4960 units. Intake manifold casting numbers located in center, under plenum; however, as it is believed the large, thick one-piece gasket was utilized, casting numbers will not be visible.
Thermostat Housing
1957 until serial number 2000 used a cast iron housing part number 2375018. After serial number 2000 an aluminum housing containing part number 3837223. All housings attach to manifold with studs and hex nuts, no washers.
7. ACCELERATOR LEVER & LINKAGE
Accelerator Lever on Firewall
Carbureted models use a firewall mounted accelerator lever arm made of cadmium plated flat steel; 1956 to mid-1957 carbureted accelerator arm does not contain a mounting hole provision for radio equipment grounding strap. Fuel injected 1957’s use semi-gloss black one-piece round rod lever.
Linkage & Springs
Linkage bellcrank at carburetor for single four-barrel has a 1/2" hole with rubber grommet and plastic sleeve; dual four-barrels use 1/4" hole with no grommets or sleeves. Dual four-barrel carburetors are connected by delayed action linkage. [pic]
Powerglide Throttle Linkage
Powerglide equipped models use throttle control linkage to the transmission. On carbureted models the linkage is interconnected via a bellcrank assembly that mounts to the left rear of the intake manifold; on fuel injected 1957 models via a bellcrank cross-shaft lever assembly bolted to the flywheel housing. [pic]
8. OIL FILLER TUBE, CAP
Oil Filler Tube
Oil filler tube will be painted silver for aluminum intake manifold applications; semi-gloss black on cast-iron. The above description regarding color or finish reflects findings on original examples; some deviations may have appeared.
Oil Cap
1956 models up to approximately late April, as well as 1957 270 and 283 hp engines used a closed, non-vented cap which is cadmium plated. This cap did not contain a decal. Later 1956 and 1957 220,245, and 250 HP engines used an open, vented breather cap, which is cadmium plated and contains an orange and black decal outlining washing instructions.
[pic]
9. FUEL PUMPING SYSTEM
Fuel Pump, Bolts & Adapter Plate
Early 1956 Corvettes use a 5/16” fuel line and fuel pump containing the numbers “4262” in the pump mounting flange casting. Very late 1956 through the end of 1957 production use a pump containing long external body screws, and the numbers “4346” in the flange casting. Both pumps contain “AC” cast into top of pump body, while the “4346” model also has AC cast on the cover bottom. Pumps do not require the use of adaptor bushings at inlet or outlet.
Fuel Filter
All carbureted models use a fuel filter with a “domed” top casting containing large “AC” letters in the center. Filter element is porous reddish ceramic type contained inside a clear glass sediment bowl retained with a wire bale and bottom thumbscrew adjustment.
Fuel injected 1957’s use a metal canister type filter, mounted at the right front of the engine by a stamped bracket that attaches with nuts to two forward studded intake manifold bolts. Filter mounts to bracket with two recessed, hex head bolts, normally with a B&H logo, and integral lock washers. FI fuel filter uses steel flare nut fittings, not brass. Very early FI fuel filter uses inlet and outlet lines which are reversed. Original FI filter contains a small weep hole at bottom.
Fuel Lines
Fuel lines are unpainted steel with flare nut fittings. Early to mid 1956 fuel line from tank to fuel pump is 5/16", while late 1956 through 1957 line is 3/8". Fuel pumps have a 45 degree inlet fitting and a 90 degree outlet fitting.
10. IGNITION DISTRIBUTOR & COIL
Ignition Distributor
If the judge is unable to verify the distributor tag number and date code, in order to award credit for this item owner may remove radio shielding. If owner chooses not to remove shielding for distributor verification, or the tag is unreadable, the 5 assigned points for distributor model tag will not be awarded.
Distributors are identified by a black Delco-Remy tag riveted to the outer housing which contains the model number and date code stampings. The date of manufacture code (listed as “SERIAL” on the tag) used for distributors contains a calendar year prefix (“5” for 1955, “6” for 1956, or “7” for 1957), followed by the month (“A” for January through “M” for December; the letter “I” was not used to represent the month of September), ending with one or two digits representing the date of the month (“1” through “31”).
Distributors with carbureted engines use an oil tube with GITS cap and felt wick for lubrication. 1957 FI distributors are lubricated by the engine’s pressurized oil system via a line and fitting assembly from the back of the engine block to the main distributor housing.
Ignition Coils
Delco-Remy Ignition Coils: 1956 ..............................1115091
1957 Carbureted............1115091
1957 Fuel Injected.........1115107
Coils, painted black, normally have the last three digits of the part number (“091” or “107”) and “12-V” embossed in the case. The coil mounting on carbureted engines is to the right of the distributor with a special “figure-8” clamp support; FI coils mount to the left of the distributor, directly to the intake manifold by means of a zinc or cadmium plated bracket.
The coil top configuration will not have squared off embossments at the lower sides of the tower to prevent wire terminal twisting; rather, the square retaining washers have a tab, which indexes into a hole on top of the coil at both terminals.
11. SPARK PLUG WIRING & RADIO SHIELDING EQUIPMENT
Wire Supports, Grommets & Heat Shields
Upper engine spark plug wire routing supports are painted semi-gloss black; and will contain applicable provisions for attaching radio ignition shielding even if car is not so-equipped.
| |Delco-Remy Ignition Distributors | |
|Year |Horsepower/ Transmission |Distributor |Advance |Approx. Serial # |
|1956 |225 HP |1110872* |Centrifugal |Early |
|1956 |225 HP |1110879* |Centrifugal |Late |
|1956 |210 HP |1110866 |Vacuum/Cent | |
|1956 |210 HP |1110869 |Vacuum/Cent | |
|1956 |210 |1110878 |Vacuum/Cent | |
|1957 |220,245 & 270 |1110891 |Centrifugal |All |
|1957 |250/manual |1110889 |Centrifugal |0001-1450 |
|1957 |250/manual |1110905 |Centrifugal |1451-6339 |
|1957 |250/powerglide |1110889 |Centrifugal |0001-1450 |
|1957 |250/powerglide |1110905 |Centrifugal |1451-6339 |
|1957 |250/powerglide |1110906 |Vacuum |4301-6339 |
|1957 |283 |1110889 |Centrifugal |0001-1450 |
|1957 |283 |1110905 |Centrifugal |1451-6339 |
|1957 |283 |1110908** |Centrifugal |3750-6339 |
* The 1110872 model was used on early 1956’s, and the 1110879 was used later,
however distributor usage overlap may have occurred.
** The 1110908 distributor with tachometer-drive was intended to be used with the RPO 579E engine with outside air intake. However, some 1110908 distributors were apparently also delivered on late 1957 FI cars intended for street use, and in such instances a closed-end threaded fitting covers the tach-drive shaft.
Apparently all early 1956 Corvettes were equipped with radio ignition shielding, even those models without a radio, and this may also apply to existence of radio grounding straps. Early 1956 Corvettes with what is commonly referred to as a .1st design. engine (to approximately serial number 1660) have unique lower engine spark plug wire routing and shielding that provides both ignition shielding as well as heat shielding from the exhaust manifolds.
Later 1956 and all1957 models have lower plug wire routing and heat shields, separate from radio interference shielding used for radio equipped cars. A lower engine cadmium plated crescent-shaped wire routing support mounts to the engine block on each side and shields the two forward spark plug wires from exhaust manifold heat. Red spark plug wire nipple boots are shielded from manifold heat by cadmium plated shields that also bolt to block both front and rear of each exhaust manifold.
Ignition Shielding
Early 1956 distributor radio ignition shield is chrome plated (not stainless) and is easily identifiable in that the top portion continues down both right and left lateral sides. After about April, 1956, the distributor shield was revised so that the sides were formed by the front and rear skirts, and it was made of stainless steel. This 2nd design 1956 distributor shield continued in use through 1957 on all carbureted models equipped with a radio.
[pic] 1957 distributor shields with fuel injection are of a different configuration due to different location of coil. Early 1957 FI distributor shield contains a continuous bottom edge for the front skirt (except for throttle opening); later ‘57 FI shield front skirt contains two added notches near the distributor. 1956-57 distributor shields have what is referred to as a “short” front skirt (opposed to later Corvettes which have a long front skirt design).
Vertical wire shields and horizontal spark plug shields are chrome plated (not stainless). Early 1956 horizontal plug shields (with 1st design engine) are two-piece; later 1956 through 1957 are one-piece. All 1956-57 radio ignition shielding is attached with chrome wing bolts.
Spark Plug Wires
Carbureted plug wire distributor boots are straight; FI boots are 90-degrees. Spark plug wires are black with red 90 degree spark plug boots. The GM Technical Specifications call for the printing on the wires to be “RADIO T.V.R.S. GM” however known original wires have been observed with “RADIO G.M. TVRS”. Either should be considered correct.
Ground Straps & Capacitors
If car is radio equipped, braided grounding straps appear at the engine mounting brackets (both sides), on the muffler tailpipe hanger (each side), or at the X-member (each side), and at the accelerator lever. 1956 and early-1957 carbureted models have the accelerator grounding strap connected from the lever arm base to a cowl vent bracket bolt on the firewall; later-1957 carbureted models connect from the upper portion of the lever arm to an intake manifold bolt. Fuel injected 1957’s connect from accelerator rod pivot mounting bracket at firewall to cowl vent bolt. Also, radio interference suppression capacitors are located at the generator, (part # 1911095) voltage regulator (part # 1917580) and coil positive terminal (part # 1929070).
12. EXHAUST MANIFOLDS & PIPES
Exhaust Manifolds
Manifolds without gaskets at head surface were installed at point of engine manufacture (Flint) and were painted engine color (either full or partial). Exhaust manifolds normally contain casting dates on inboard cylinder head side and, therefore, may be unreadable. The manifold bolts use tab locks and washers on the front and rear bolt sets (not on center bolts), center bolts have lock washers. Only 1957 fuel injected models were specified as using exhaust crossover pipes. Also, l957 FI models have a spacer in place of the normal right-hand manifold heat control valve, and do not contain a machined hole in the right-hand manifold for mounting of a carburetor choke heat tube. The 1956 heat control valve does not utilize a “doughnut” gasket and will have “TOP” cast on body. The 1957 valve, or spacer will use a “doughnut” type gasket and will have “UP” cast on body. 1956 only center heat shields are attached to the exhaust manifold with the two center bolts. Heat shields have a manufacture logo stamped between the two bolts of (sRo).
Black preservative paint was applied to the exhaust pipes at source. Burnt paint and/or mild oxidation of manifolds and pipes is acceptable.
| |Exhaust Manifold Casting Numbers |
|Year |Left Hand |Right Hand |Applications |
|1956 |3725563* |3725563* |1st design all engines |
|1956 |3731557 |3731558 |2nd design all engines |
|1957 |3733975 |3733976 |Carbureted |
|1957 |3733975 |3733976** |Fuel Injected |
* 2 bolt flange ** not machined for choke heat tube
13. ENGINE OIL
Ventilator Pipe
Crankcase ventilator road draft pipe is painted semi-gloss black and attaches at top rear center of block, passing down along the right-hand side of the flywheel housing.
Dipstick Tube & Pressure Line & Fittings
Crankcase oil dipstick and tube mounts on left-hand side of engine; except for early 1956 engines to approximately serial number 1660, which mount on right side and enter crankcase at oil pan. Dipstick is flat steel and is bent at end to form a finger hole.
Oil pressure line runs through the firewall to the rear of the intake manifold where it attaches with a compression fitting. Original steel lines have a loop in them after exiting the firewall prior to attaching to the manifold.
14. MOTOR MOUNTS, WATER PUMP, FAN BELT
Motor Mounts
Motor mount brackets attached to frame are painted chassis black. Engine cross-mount attached at water pump is painted engine color, and does not contain cutout for water pump by-pass as later model Corvettes use. Further, correct 1956-57 engine cross-mount does not contain a lower right-hand relief allowing access to engine block freeze plug.
Water Pump
1956 water pump casting number is 3704911with boss at housing top, 1957 is 3736493; how-ever, casting number is not visible due to installation of fan pulley and engine cross-mount. Pumps do not contain casting dates. All water pumps had a flat cover plate secured to the rear of the pump with six slotted pan head screws. If heater equipped, the heater hose pump fitting is 5/8" curved design. 1957 used a ¾” cad plated nipple.
Fan Belt
Generally, two fan belts were used for 1956 and 1957. The part numbers for each are moulded-in; “3712555” and “3738437”, and both are un-notched. Belt number 3738437 was considered a “high speed drive” belt.
15. OVERALL CLEANLINESS
Overall Cleanliness
Do not deduct for slight amounts of road dust, oil seepage around seals, etc. Deductions are appropriate for excessive grease, oil and caked-on dirt.
CHASSIS SECTION
16. ELECTRICAL SYSTEM
Generator
The Delco-Remy electrical DC generator with tachometer drive unit mounts to the left-hand exhaust manifold, and is model number 1102043 for all 1956-57 engines except 1957 RPO 579E (FI with outside air intake). The 1l02043 generator uses a rubber cushioned mount and is rated at 30 amps. Aluminum end plates appear unpainted.
A 1955 Corvette generator, model 1102025 (using a solid mount), may have been used on a very few early 1956 Corvettes (possibly in factory race applications).
1957 RPO 579E is specified in the Factory Assembly Manual as using 30 amp generator model number 1102042, without tach-drive.
The generator model number will be stamped into a red Delco-Remy tag which is riveted to the generator housing. Also stamped into the tag will be a manufacturing date code which is shown on the tag as a “SERIAL” number. This date code will consist of a number designating the calendar year (.5. for 1955, “6” for 1956, or “7” for 1957); followed by a letter indicating month of manufacture (“A” for January, “B” for February, an so-on); ending with a number, or numbers, indicating the date of the month (“1” through “31”). Date code will precede approximate assembly date of vehicle.
| | Delco Remy Generator & Regulator Date Codes |
|A |January |D |April |G |July |K |October |
|B |February |E |May |H |August |L |November |
|C |March |F |June |J |September |M |December |
The generator housing is painted semi-flat black; end frames may appear painted semi-flat black (1956), or unpainted (1957). Front end frame is same diameter as generator fan and the frame will not have a part number or cast reinforcing ribs. All 1956 and 1957 engines used generator end frames that mount close to the exhaust manifold. To check clearance, finger tips should not be able to be squeezed between the generator body and manifold. On later year high horsepower engines, generator is mounted 3/8” further away from manifold.
Generator field terminal uses a round red paper tag warning against connecting a radio by-pass condenser, on all vehicles, even those not radio equipped.
1956 engines and 1957 base 220 horsepower engines use a generator fan pulley measuring 3-3/8" in diameter with a narrow 3/8" belt groove. Later 1956 dual four-barrel engines may have used a pulley measuring 3-5/8" in diameter with a 1/2" wide belt groove. 1957 dual four-barrel and fuel injected engines use a pulley measuring 3-5/8" in diameter with a 1/2" wide belt groove. The 1957 RPO 579E generator 1102059 is specified as using a 4" diameter pulley with 1/2" belt groove.
Mount & Brace
The generator brace may contain part number identification “3704884” and is painted engine color; except for possibly some black painted braces on mid-to-late 1957. A black painted heat shield mounts between the exhaust manifold and the generator bracket, protecting the rear bushing; the 1956 shield mounts using a single manifold bolt, the 1957 shield is longer and mounts using two bolts.
Tach Drive Cable
Tach-drive unit may appear painted semi-flat black (1956), or unpainted (1957). Tachometer drive cable housing is unpainted metal.
Voltage Regulator
Regulator: The Delco-Remy voltage & current control regulator mounts to the inner fender adjacent to the generator; except for 1957 RPO 579E and 684, which mount to the radiator fan shroud (right-hand generator and regulator mounting for RPO 579E is unverified). The regulator carries model number 1119001 and a date of manufacture code, which are stamped into the side of the mounting base. The regulator cover is painted gloss black. An attempt should be made to verify voltage regulator model number and date code.
Horn Relay
Horn Relay: Contains an identification stamping “913” and voltage stamping on either the front or back of the mounting flange. 1956 and early 1957 relays mount with terminals pointing up; later 1957’s after approximately serial number 2700 mount the relay with terminals facing forward.
17. ELECTRICAL WIRING HARNESSES
Main Harness
Main underhood wiring harness is wrapped with non-sticky vinyl tape. Check for proper location of harness and connector routing metal clips. Wiring harnesses and connections should not contain any paint overspray.
Ballast Resistor
Firewall mounted ballast resistor attaches with either a Phillips or a clutch-head screw. The bracket has a small ¼” notch protruding from the end near the mounting hole and does not contain a dot or stripe marking.
Generator to Regulator Harness
Generator to regulator harness wiring is shielded (braided wire) and vinyl tape wrapped. Field and armature terminals at generator are round and slightly larger than the retaining nuts. 1956 woven ground field harness may be grounded on either side of the voltage regulator by one of the large phillips screws.
Temperature Sending Unit
Black fabric wire loom was used for routing the engine temperature sensor wire along the engine valve cover (left side base engine; right side optional engines), as well as the headlamp wiring harnesses.
It is generally believed that 1956 models were fitted with a temperature sending unit having a vertical pin type wire terminal attachment, while 1957 changed to a “T” style slide on clip. This would affect both the sending unit and the wire end clip.
Power Top / Window Circuit Breaker & Wiring
Hydraulic folding top equipment was available as an option (RPO 473). However, Chevrolet data indicates that early 1956 models through about March of 1956 production were initially not available without power top equipment.
Vehicles equipped with power top and/or windows have a circuit breaker mounted on the upper right-hand side of the firewall. It has a tan 12 gauge wire coming out of the main power top wire harness connected to it. On 1956 Corvettes the circuit breaker top is molded “Woods Elec Co” and patent numbers are evident in addition a “40X” is stamped into the metal bracket.
Although not completely visible, judge should attempt to verify electrical wiring, limit switches, hydraulic components, lines, and mounting brackets on vehicles so-equipped. Further, if car appears to have been not so-equipped, judge should attempt to determine if power top hydraulic and electrical components have been removed (including control switch mounted under instrument panel). Full deduction is appropriate for vehicles with evidence of power top equipment removal. Full credit should be given for vehicles legitimately not-so-equipped.
[pic]
18. BATTERY & CABLES
Use Standard Deduction Table for awarding originality points.
Battery
The battery has a hard rubber case with a tar like substance, some reproductions may exhibit a
hard rubber top which is incorrect. Appropriate deductions should be made for these batteries.
The battery is installed with terminals facing forward; negative post inboard. Delco OEM battery
for 1956 is model 2SMR53 and that designation appears both on the medallion side face and on the top of the battery. 1957 battery is also model 2SMR53 (and is so designated on the side medal-lion), however the top identification was changed to read “CAT. NO. 458”. Centerline between terminal posts runs within visible top covers showing through tar. Both have a hard rubber case and rubber separators and are so identified. DELCO medallion on side of case is unpainted.
The cell vent caps are molded yellow plastic with “DELCO” in short block capital letters. The word DELCO on each cap is not highlighted in black.
Batteries are marked with a code, which designates the year, month and place of manufacture.
[pic]
Retainer & Fastners
Metal battery retainer contains a sheet metal heat shield and is painted semi-flat black. Original heat shield does not contain either a top relief for cable clearance or clip attachment hole, as used with later model shields. Rubber pads are used at all four corners to cushion battery. Retainer J-bolts are 5/16", not threaded entire length, and use hex-nuts (not wing-nuts) and plated flat and lock washers.
Cables & Felt Washer
Negative cable is an un-insulated 1/2" to 3/4" wide woven tin-plated strap, mounted to the in-board negative battery terminal post, and grounded to the starter. 1956 ground is attached to the top starter mounting hole, starter side. 1957 ground is attached to the top starter mounting hole, bellhousing side. Positive cable is black vinyl insulated, 9/32" diameter, and retained to the fender skirt by a metal clip.
Both positive and negative cable terminal ends are identified by .P. or .N. respectively. They are attached to the battery posts requiring a 9/16" wrench. The positive cable nut contains a shoulder; the negative cable nut is thin without a shoulder. Bolts should extend no more than approximately ½” past nut as installed.
A grey chemically treated anti-corrosion felt washer is installed at the positive battery post, under the cable terminal (no felt washer at negative post).
19. HEATING SYSTEM
Heater Air Hose
Optional fresh air heater (FOA 101) uses a fabric-covered coiled-wire duct hose retained against the right inner fender by a black metal bracket. This hose is connected to a screen-covered flange attached to an opening in the radiator skirt. The duct hose is retained to flange and unpainted heater plenum by cadmium plated band type clamps with special slotted pan-head adjusting screw. Heater plenum is attached with fasteners installed from cockpit side of the firewall and extend approximately 1 1/8” into the engine compartment.
Heater Coolant Hoses
Heater coolant hoses are black rubber and may, or may not, contain ribs as vendor identification. Heater hoses are connected to engine and heater core with SAE type “E” (Corbin) clamps. Hoses are routed along right inner fender by three hose retaining clips. [pic]
Inlet Plenum or Block Off
Heater plenum is attached with fasteners installed from cockpit side of firewall.
Vehicles not equipped with a heater use a black, stamped steel block-off cover over the
firewall opening, retained by fasteners which install from the cockpit side of the firewall. Also, a block-off cover fills the hole in the radiator skirt, and engine heater hose connections use standard square-head plumber pipe plugs, painted engine color (except painted silver on aluminum intake manifolds).
Early 1956 Corvettes (to approximately serial number 1210) will be equipped with a 1955 Corvette re-circulating air type heater, with a manual water shut-off valve spliced into the heater hose.
20. WIPER MOTOR & WASHER SYSTEM
Wiper Motor
The wiper motor contains the stamped part number (as listed below) on the front cover. The motor gear housing attaches to the firewall mounting plate with two washer-head Phillips screws, and a small sheetmetal “L” bracket supports the end of the motor housing to the firewall (“L” bracket used on all 1956, and inconsistently during 1957). A ground wire attaches to a cowl vent lever support bolt on the firewall.
1956..............................................................5047924 1957 to about #1400.....................................5047984 1957 about #1400 on (slow-park design)......5047991
Washer System
Windshield washer equipment was optional (FOA 109). A driver operated foot pump actuated a coordinator connected to the wiper motor via an unpainted bowden cable which turned on the wipers as a quantity of washer sol-vent was squirted onto each side of the wind-shield.
1956 models use a reservoir bag with vinyl-coated fabric back and vinyl front in blue containing blue and white “Chevrolet” script and bow-tie shield (bag front is partially translucent to allow viewing of washer solvent fluid level). [pic]
The bag is attached with three eyelets to two metal brackets attached to the left inner fender. 1956 washer bag was capped by a rectangular black plastic Trico manufactured valve with two horizontal connecting tubes. Some carry over to 1957’s. 1957 washer “jar” is Trico brand hard plastic white container with red lid reading “Coordinated Washer” in large molded letters. A black rubber hose air line runs from the foot pump to the reservoir; then a hose carrying fluid runs from the reservoir to an opening in the firewall (where it continues to a plastic “T” fitting under the interior instrument panel).
Evidence suggests that vehicles without washer equipment will appear with reservoir mounting holes drilled and then filled-in at the left inner fender; Bowden cable opening at left upper firewall will appear with rubber cable grommet, whose hole will be plugged with sealer; non-washer cars will show no evidence of nozzle holes at cowl.
21. BRAKE SYSTEM
Master Cylinder
The brake master cylinder was manufactured by the Delco Moraine Products Division of Dayton, Ohio, and is so-identified on the casting. The raw casting was done by Central Foundry Division, whose “wagon-wheel” logo appears on the part. The casting number is normally located on the outboard side of the part, just above the 1" Dia. designation used for cylinder bore identification. The master cylinder part number .5454480. and “320-G” are stamped into the plug at the front of the fluid reservoir. The hex top filler cap is cast iron and contains “USE G-M-C BRAKE FLUID” and its casting number as listed in the following chart.
Year Part # Casting # Filler Cap 1956....5454480....5450233*.....5300880 1957....5454480....5456022*.....5300880
* Some usage overlap of the 5450233 or 5456022 castings may have occurred on early 1957 models. Cylinder 5456022 contains an un-machined cast boss on the inboard side (used for brake light switch on Buick application). Last three digits in the casting number (“022”) are same size as all other digits (not larger, as in later master cylinder castings). Both master cylinders may also contain a cast alpha/numeric code. This is presently thought to be a casting mold designation, rather than a casting date code.
Master cylinder for 1956 and 1957 may appear painted semi-gloss black, or unpainted raw casting (exact configuration not yet verified).
Brake Lines & Blocks
Brake fluid lines are unpainted cold pulled steel, not stainless.
Park Brake Cable
The park brake cable is also unpainted.
[pic]
22. ENGINE COMPARTMENT BLACKOUT PAINT
Blackout Paint
Blackout paint is flat to semi-flat black, matching underside of hood. Items installed prior to painting include hood hardware (except hood support), radiator support, and electrical wiring harness retainer clips. Wiper motor mounting plate was normally installed before blackout painting; however, some original exceptions are known to exist.
23. UNDERSIDE of HOOD PAINT & WEATHERSTRIP
Paint Color
Underside of hood panel is flat to semi-flat black, matching engine compartment black-out.
Paint Margin
Exterior body paint was applied to the underside of the hood panel lip, about 1-inch wide, stopping at start of radius of underside reinforcement panel. The paint margin line was achieved with masking tape and may be slightly irregular.
Hood Weatherstrip
A length of weatherstrip (identical to that used on doors and trunk, containing an “S” within a square, manufacturer’s logo) is cemented to the rear hood panel lip, across the full width (but not going around the rear corners of the hood), thus covering the rear portion of the paint margin. Weatherstripping cement was yellow in color, and brush applied, and application may be excessive. Weatherstrip has an internal white or beige reinforcement cord, which can be seen on any exposed end of the weather strip.
24. HOOD HARDWARE
Hood Hinges
Hood is hinged at front with double-link hinges installed at each side of the radiator support, along with spring-loaded hood rest assemblies. Two small black hard rubber bumpers attach to the front of the body, above the radiator, each with two Phillips tapping screws, to act as limiters for front edge (lip) of hood panel, when closed. These two bumpers install with the shelf sloping upward toward the rear, thus matching slope of hood lip when closed. Bumpers should display some body color overspray.
Rear of hood panel contains two spring-loaded hood lock assemblies with rubber bumpers. Hood latches are installed at the body firewall.
Hood Support
The hood support is cadmium plated which can appear with an iridescent surface color, and does not appear with paint overspray. Spring retainers holding the pivots together are a bluish metal almost black in appearance.
Rear Latches & Hood Lock
Rear of hood panel contains two spring-loaded hood lock assemblies with rubber bumpers. Male hood lock pins are smooth finish not serrated like some later replacements. Hood latches are installed at the body firewall.
All metal items listed above are cadmium plated, except for the coil springs, which are painted gloss black. However, these hardware items were installed prior to exterior body paint and engine compartment blackout painting, and therefore may appear with paint overspray, in varying degrees, much of which may not have completely adhered to these lubricated parts. The two front black hard rubber hood bumpers may or may not appear with exterior body color paint overspray.
25. ENGINE COOLING SYSTEM
Radiator Fan
The four-blade engine fan is painted semi-gloss black. 1956 to mid-1957 fan uses staggered, straight blades; fan blade tips have slight forward curve for remainder of 1957 production.
Water Pump Pulley
Pump pulley used on 1956 engines and base 220 horsepower 1957 engines has a smooth conical taper from the belt groove to the fan mount; 1957 optional engine fan pulley has a “stepped” taper and 1/2-inch “deep-ride” belt groove.
Crank Balancer Pulley
Crankshaft pulley is riveted to the harmonic balancer on all engines (except 1957 283 horsepower, and possibly some 270 models), and this riveted unit is painted engine color. Generally, early 1956 engines, [pic]
and later 1956 and 1957 base engines use a riveted pulley with narrow 3/8" belt groove. Later l956 dual four-barrel and 1957 245 and 250 horsepower models possibly used a riveted pulley with “deep ride” 1/2-inch belt groove. 1957 283 horsepower high-lift cam engines (and possibly some 270 horsepower engines) use an orange painted balancer, with separate bolt-on, “deep-ride” (1/2-inch belt groove) pulley, painted semi-gloss black.
26. RADIATOR SYSTEM
Radiator & ID Tags
The gloss black painted copper radiator will have a Harrison Division manufacturer’s tag soldered to the center, inlet side of the upper core tank, containing the part number “3l33689”, and a manufacturing date code consisting of two digits representing the calendar year (“55”, “56”, or “57”), followed by a letter representing the month (“A” for January, “B” for February, and so-on). The radiator date must precede the approximate vehicle assembly date. Radiator contains an antifreeze “WARNING” gum-label (white with green printing) attached to the upper core tank adjacent to the coolant filler. Antifreeze tags were only installed on St. Louis built cars from mid-October to April time period. Antifreeze was considered a dealer-installed item in 1956-57. The factory only installed antifreeze to protect cars shipped during the winter months.
Hoses & Clamps
Radiator hoses are molded black rubber, containing GM identification and part number printed on the hoses as follows: Base engine upper hose is #3715184; dual carbureted and FI upper hose is #3728490; lower radiator hose is #3715183 for all applications. Lower hose is secured with SAE type .E. (Corbin) spring clamps. 1956 upper hose is secured with Corbin clamps; 1957 may use Corbin spring clamps (early), SAE types “B” (slotted) or “D” (solid band) with adjustment screw (change to screw type “B” and “D” clamps occurred during 1957 production to prevent upper hose from blowing off under pressure).
Pressure Cap
Radiator filler caps are rated at seven-pounds pressure, and three plated examples are illustrated.
[pic]
Fan Shroud
Fan shrouding is four piece; single upper piece with three lower pieces. Center top of upper shroud measures 7" deep. Shrouding is painted semi-flat black. Shrouding is assembled with clutch-head fasteners. Manufacturer’s logo/stamp should appear on the inside of the upper fan shroud near the bottom on each side near the openings for the stabilizer bar and the radiator.
27. FRONT SUSPENSION & STEERING
Front Suspension
Stabilizer bar measures 5/8” diameter. Front stabilizer bar links are cadmium plated and may show black overspray. Front suspension and cross member assembly was sprayed after assembly but before mounting to the frame. Some suspension and cross member assemblies are normally a higher gloss black than the chassis. Third arm bearing forging contains a foam circular gasket covering the entire grooved surface.
Information to those cars equipped with RPO 684, Heavy Duty Brakes & Suspension: Front stabilizer bar measures 13/16” diameter, as opposed to standard 5/8” bar. Quick steering adaptor will be present, mounting to front crossmember. Front springs are formed from larger diameter steel and have fewer coils. The quick steering adapter uses tapered bolts with castled nuts on both ends to mount the tie rods.
28. STARTER SYSTEM
Starter Motor
Solenoid and starter model number and date code will not be judged.
1956 starters used a solenoid with exposed plunger and lever linkage; for 1957 the solenoid plunger and lever linkage were fully enclosed in the starter pinion casting. Starter assemblies (less mounting bolts) are painted semi-flat black. Forward end of starter housing is supported to engine block with a metal brace. Starter motor is attached to engine block with three bolts, two bolts and one stud is acceptable. 1956 road draft tube bracket attaches to the lowest mounting bolt. 1957 road tube attaches to the top mounting bolt.
Year Starter Solenoid Powerglide Relay 1956......1107627......1119767........1116904 1957......1107664......1119919........1116904
Starter model identification and date of manufacture code (as described for distributors and generators) will be stamped into a red Delco-Remy tag riveted to the motor housing on 1956 starters; the use of an identification tag was eliminated on 1957 starters, and the stampings were made directly to the starter housing.
Solenoid
The 1956 solenoid part number will be stamped into its mounting collar; the 1957 solenoid stamping is found on the housing case.
Powerglide Relay
A firewall mounted starter relay was used only on Powerglide equipped cars, and is stamped “904” on the mounting flange (number may not be visible when relay is installed). The relay cover is painted gloss black.
29. OIL PAN & FILTER
Oil Pan
1956 Corvettes until serial number 1660 oil dipstick exited the right side of the oil pan. Later engines and all 1957’s the oil dipstick was integrated into the engine block. Oil pan bottom is formed into three steps with drain plug located at the bottom rear center. 1956 drain plugs have been verified containing an .A. within a circle.
Oil Filter Housing
A full-flow oil filter unit is mounted at the lower left rear of the cylinder block. The oil filter canister contains a replaceable filter element inside. The canister is painted semi-gloss black.
Filter Screen Instruction
The filter contains a white silk-screened AC label (not a decal) identifying the unit as “TYPE PM-11”, as well as instructions to “REPLACE ELEMENT EVERY 6000 MILES WITH AC TYPE PF-131”.
30. TRANSMISSION
30 A. Automatic Transmission
Powerglide transmission is cast iron, and is optional.
Filler Tube
Powerglide transmission dipstick tube and wire rod handle are painted semi-gloss black.
Neutral Safety Switch
Neutral safety switch, shield, and mounting hardware are unpainted, and mount to left side of case.
30 B. Manual Transmission
Standard transmission is three-speed; optional transmission is 1957 RPO 685 four-speed (4-speed available May 1, 1957; approximately serial number E57S103500). All transmissions are cast-iron; except for aluminum tailshaft housing and side covers on 1957 four-speed.
Bellhousing
Manual transmissions use a cast-iron bellhousing, containing passenger car mounting bosses, and is painted engine color. Although not judged, bellhousing casting numbers are: 3704922 for early to mid-1956; 3733365 for mid-1956 through end of 1957 production; and all contain casting dates.
Clutch Linkage
Clutch linkage is painted semi-gloss black. The clutch fork is engine color.
30 C. Speedometer Cable
Speedometer cable housing is cadmium plated.
Although the transmission manufacturing code stampings will not be judged, they are described as follows:
Prefix Plant Transmission
C...........Cleveland......….Powerglide
S...........Saginaw........….3 Speed
W..........Warner Gear.….4 Speed
Powerglide & 3-Speed: Immediately following the transmission prefix will be one or two digits indicating the month of production (“1” for January through “12” for December), followed by two digits representing the date of the month (“01” through “31”). Powerglide transmissions also carry a suffix letter indicating work shift (“D” for day shift; “N” for night shift). The Powerglide transmission will carry the identification stamping on the rear face of the case, in the lower right-hand corner. The 3 speed stamping will appear on the rear face of the case, in the upper right-hand corner.
Warner 4-Speed: Immediately following the .W. prefix will be a letter indicating month of manufacture (“A” for January, “B” for February, and so-on), then one or two digits indicating the day of the month (“1” through “31”); followed by the calendar year of manufacture, and “1”, “2”, or “3”, indicating work shift.
31. CHASSIS & REAR AXLE
Frame, Brake & Fuel Lines
Chassis paint is a low-grade, slightly dulled gloss black; not high-gloss or flat. Chassis finish was not show-quality. The rear cross members differ from 1956 to 1957. The 1956 and early 1957 cross members have five holes across the bottom. Late in 1957 the cross members have four holes and captured nuts welded to the inside to hold the 1958 bumper brackets. Fuel and brake lines are unpainted and are routed along inboard side of right-hand frame rail.
Inspect chassis frame rails and rear frame crossmember for signs of rust-through.
Frame Stencil
For 1956 the frame stencil number from GM is 3722371, A.O. Smith part #.s 303190-30, 303190-31, 303190-32. For 1957 the GM # is 3733595, A.O. Smith part #’s 303190-40, 303190-41, 303190-42, 303190-43. All are in red paint ¾” high, upside down.
Rear Suspension
Late 1957 models appear with an additional pair of rear spring bumpers added to frame forward of axle. Rear springs and front & rear shock absorbers are painted black, and shock bodies are spiral. Standard rear springs with steel tipped cotton type liners have a groove running the entire length of each leaf and are banded together with three rubber cushioned stainless steel straps. [pic]
The rear spring shackles are straight along the rear edge. Later models will show a distinct dogleg to the rear edge of the shackle bracket.
Information relating to those cars equipped with RPO 684, Heavy Duty Brakes & Suspension: Shocks are smooth, not spiral and measure 1 3/8” diameter. Rear springs have five leaves and are bound with six riveted steel clamps. Brake Backing plates have hand cut vent holes covered with spot welded screen and special air ducting will also be present.
Rear Axle Housing Assembly, Driveshaft, Rebound Straps
Rear axle rebound straps are unpainted, and attached to frame kick-up with rivets, not nuts and bolts. Rebound strap rivets are installed pointing toward the front of the car. Models equipped with optional Positraction rear axle, have a vent pipe attached to axle housing; non-Posi axles use breather cap. Positraction gear housings have an “X” cast in the left side until approximately March of 1957, when it was replaced with a “P” through the end of production. Generally, 1956 rear end housings are not equipped with a drain provision; 1957 housings are.
Mufflers, Tail Pipes & Hangers
OEM mufflers use welded-on forward exhaust extension pipe (deduct for separate clamp-on service extension pipe). Mufflers and pipes were painted black, except for the last tail pipe, which was unpainted. (do not deduct if paint is burned off). Check for excessive tailpipe length extending beyond the bezel.
32. OVERALL CLEANLINESS
Overall Cleanliness
Do not deduct for slight amounts of road dust, oil seepage around seals, etc. Deductions are appropriate for excessive grease, oil and caked-on dirt.
33. REAR AXLE RATIO CODES
Rear Axle ratio codes are not judged but are presented as follows: Note: The first prefix letter .A. indicates that the Corvette axles were manufactured at Chevrolet’s Detroit Gear & Axle Plant. The prefix code letters are followed by one or two digits indicating month of manufacture (“1” or “01” for January through “12” for December), and two additional digits indicating date of the month (
01” through “31”). Axle code stamping appears on the front, right side of carrier. Casting numbers are 3725899 standard; Positraction cast number is 3743833.
| | | |Rear Axle Ratio Codes |
|Year |Prefix |Ratio |Type |Equipment |
|1956 |AD |3.27:1 |Std. |Manual Trans. |
|1956 |AE |3.55:1 |Std. |Powerglide |
|1957 |AE |3.36:1 |Std. |Powerglide |
|1956-57 |AH |3.70:1 |Std. |Manual Trans. |
|1956 |AJ |4.11:1 |Std. |Manual Trans. |
|1957 |AN |3.70:1 |Posi |Manual Trans. |
|1956 |AJ |4.11:1 |Std. |Manual Trans. |
|1957 |AP |4.11:1 |Posi |Manual Trans. |
|1957 |AQ |4.56:1 |Posi |Manual Trans |
|1957 |AS |3.70:1 |Posi |H.D. Brakes & Suspension |
|1957 |AT |4.11:1 |Posi |H.D. Brakes & Suspension |
|1957 |AU |4.56:1 |Posi |H.D. Brakes & Suspension |
Note: 1957 AE coded rear axles, which are indicated on the chart as having 3.36:1 ratio, may actually be factory equipped with the 3.55:1 gear set, as in 1956.
34. FINAL MONTHLY SERIAL NUMBERS
Final monthly serial numbers are not available, however, it is known that 1956 Corvette production began sometime early in January of 1956; and ended approximately September of 1956. A Chevrolet Service Bulletin states that E56S003844 was assembled August 8, 1956.
|1956 Model Year |1957 Model Year |
|Month - Day |Serial Number |Month - Day |Serial Number |
|3/9 |1202 |October 1956 |580 |
|4/6 |1701 |November 1956 |1070 |
|4/12 |1759 |2/12/57 |2060 |
|4/16 |1794 |2/26/57 |2305 |
|5/4 |2096 |3/4/57 |2433 |
|5/10 |2241 |3/29/57 |3098 |
|5/18 |2308 |4/26/57 |3441 |
|5/24 |2475 |May 1957 |4331 |
|5/30 |2605 |June 1957 |4924 |
|6/5 |2653 |July 1957 |5584 |
|6/12 |2709 |August 1957 |6229 |
|7/17 |3249 |September 1957 |6339 |
|8/8 |3844 | | |
35. OPTIONS & ACCESSORIES
|1956 Options and Accessories Installed by Chevrolet |
|FOA101 |Outside Air Type Heater |
|FOA102 |Transistorized Signal Seeking Radio |
|FOA107* |Parking Brake Alarm |
|FOA108* |Courtesy Lights |
|FOA109 |Windshield Washer |
|FOA290 |6.70x15"4-PlyWhitewallTires |
|RPO313 |Powerglide Automatic Transmission |
|RPO419 |Auxiliary HardTop (Painted body color)** |
|RPO426 |Electric Window Controls |
|RPO440 |Color & Trim Combinations (Single &Two-Tone Exterior) |
|RPO449 |Special High Lift Camshaft (withRPO469Only) |
|RPO469 |Dual Four Barrel Carburetor 225 Horsepower Engine |
|RPO470 |White or Beige Convertible Top (in place of Standard Black) |
|RPO471 |3.27:1 Rear Axle Ratio |
|RPO473* |Hydraulic Folding Top Mechanism |
* 1956 Corvettes (through about March, 1956) were initially not available without these options.
** Hardtop could be ordered in place of a convertible top (at no extra charge) beginning abut April, 1956.
|1957 Options and Accessories Installed by Chevrolet |
|FOA101 |Outside Air Type Heater (not available with RPO684) |
|FOA102 |Transistorized Signal Seeking Radio |
|FOA107 |Parking Brake Alarm |
|FOA108 |Courtesy Lights |
|FOA109 |Windshield Washer |
|RPO276* |15x51/2"WideWheels |
|FOA290 |6.70x15"4-PlyWhitewallTires |
|RPO313 |Powerglide Automatic Transmission (available with 220, 245, 250hp) |
|RPO419 |Auxiliary HardTop (with or without softtop) |
|RPO426 |Electric Window Controls |
|RPO440 |Color & Trim Combinations (Single & Two-Tone Exterior) |
|RPO469A |245 Horsepower Engine with Dual Four Barrel Carburetion |
|RPO469C |270 Horsepower, 2x4 Carburetion & Hi Lift Camshaft** |
|RPO473 |Hydraulic Folding Top Mechanism |
|RPO579A |250 Horsepower Engine with Ramjet Fuel Injection |
|RPO579B |283 Horsepower Fuel Injection & Hi Lift Camshaft** |
|RPO579C |250 Horsepower, FI & Powerglide Transmission |
|RPO579E* |***283Horsepower, FI & Hi Lift Camshaft - Special |
|RPO684 |Heavy Duty Brakes & Suspension (RPO677, 678, 679 Only) |
|RPO685 |Close Ratio 4 Speed Synchromesh Transmission |
|RPO677 |3.70:1 Positraction Rear Axle** |
|RPO678 |4.11:1 Positraction Rear Axle** |
|RPO679 |4.56:1 Positraction Rear Axle** |
* Options made available approximately April, 1957
** Available only with standard 3 speed or optional 4 speed transmission.
*** Same engine as RPO 579B, with Outside Air Intake and Mechanically Driven Tachometer mounted on steering column.
**** Available about May 1, 1957.
36. COLOR AND TRIM COMBINATIONS
Three Chevrolet color charts are presented on the following pages of this manual. The first chart (labeled as 1956) is taken from the “1956 Corvette Engineering Achievements & Dealer Product Manual” published in January, 1956, and represents the various exterior and interior color combinations normally available throughout the 1956 model year. It should be noted on this 1956 chart that the Arctic Blue Corvette is the only car specified as being available with either Red or Beige trim. Another color chart, dated 10-29-56, for early 1957 Corvette models was published by the Chevrolet Engineering Department in their “1957 Corvette Specifications” book, and it represented the color combinations available at start of production 1957. Although not included in this manual, it is identical to the 1956 chart.
The second chart presented is taken from a 1958 Chevrolet dealer service and parts publication, and was originally intended to represent combined 1956-1957 production (and is so labeled). Note that this chart expands the number of body colors available in a choice of either Red or Beige trim. Specifically, Onyx Black, Venetian Red, Polo White, and acrylic paint color Inca Silver (new during 1957) became available in a choice of trim combinations. Further, expanded convertible top color availability also is represented on this chart, as are the listed changes shown as 1st and 2nd design for the instrument panel color on the Onyx Black and Polo White models with Red trim. It is therefore believed that this third chart represents both 1956 as well as early late 1957 color combination availability.
The last chart is Chevrolet Engineering Blueprint # 3722955 dated 4/29/57. It is thought to be a generally accurate representation of color combinations available sometime during mid 1957 to the end of production. The new Lucite acrylic paint colors (Inca) Silver and (Imperial) Ivory appear on this blueprint. Note that this fourth chart does not show the availability of Red trim with an Arctic Blue model (which had previously been offered), and that it reflects the trim colors shown as 2nd design in the 1956-57 combined chart.
Several obvious errors regarding individual parts do appear on the presented charts. The first and second charts each refer to a “Plastic Sidewall Panel” (in door) when it is metal; and the 1957 blueprint chart lists a white plastic door lock knob (it is actually chrome metal), and an Elascofab (vinyl) shift boot are specified in trim color (when it is actually black rubber).
Note: The color “Silver” listed on the following charts as being the available two-tone cove color for the Onyx Black, Arctic Blue, and Polo White bodies, is NOT the same color as exterior body Lucite (acrylic) paint color Inca Silver introduced during 1957.
|1956 Corvette Exterior Color and Trim Combinations |
|Body Color |Door & Fender |Convertible Top |Wheels |Interior |Upper Instrument|Lower Instrument |Steering |
| |Depression* | | |Trim |Panel |Panel, Steering |Wheel |
| | | | | | |column, signal | |
| | | | | | |housing, steering | |
| | | | | | |wheel hub & sidewall | |
| | | | | | |panel | |
|Onyx Black |Silver |Black or White |Black |Red |Black |Red |Red |
|Aztec Copper |Beige |Beige or White |Copper |Beige |Copper |Beige |Beige |
|Cascade Green |Beige |Beige or White |Green |Beige |Green |Beige |Beige |
|Arctic Blue |Silver |Beige or White |Blue |Red |Blue |Beige |Red |
| | | | |Beige |Blue |Beige |Beige |
|Venetian Red |Beige |Beige or White |Red |Red |Red |Beige |Red |
|Polo White |Silver |Black or White |Red |Red |Red |Beige |Red |
* Front fender depression is also available painted body color.
|1956 Interior Colors and Fabrics |
|Area |Material |Trim Combination |
| | | |Red |Beige |
|Seats |Cushion |Waffle Pattern Vinyl Waffle Pattern | | |
| |Backrest Cushion Bolster |Vinyl Leather Grain Vinyl Leather | | |
| |Backrest Bolster |Grain Vinyl | | |
| | | | | |
|Sidewalls |Top Roll |Leather Grain Vinyl Waffle Pattern |Red |Beige |
| |Upper Panel Lower Panel Arm|Vinyl Leather Grain Vinyl Leather |Red |Beige |
| |Rest Decorative Molding |Grain Vinyl |Red |Beige |
| |Scuff Pad |Metal |Red |Beige |
| | |Textured Metal |Bright Bright |Bright |
| | | | |Bright |
|Cowl Side Kick Panels | |Waffle Pattern Vinyl |Red |Beige |
|Windlace | |Leather Grain Vinyl |Red |Beige |
|Floor Covering | |Carpet |Red |Copper |
|Top Storage Well | |Paint |Red |Beige |
| |Mat |Rubber |Red |Black |
|Rear Compartment | | | | |
| |Trim Board |Composition Board |Red |Beige |
| |1956 -57 Corvette Exterior Color and Trim Combinations | |
|Body Color |Door & Fender |Convertible |Wheels |Interior Trim |Upper Instrument |Lower Instrument Panel,|Steering Wheel |
| |Depression* |Top | | |Panel |Steering column, signal| |
| | | | | | |housing, steering wheel| |
| | | | | | |hub & sidewall panel | |
|Onyx Black |Silver |Black, White or |Black |Red |Black |Red (1st des) Beige(2nd|Red |
| | |Beige | |Beige |Black |des) | |
| | | | | | |Beige |Beige |
|Aztec Copper |Beige |Beige or White |Copper |Beige |Copper |Beige |Beige |
|Cascade Green |Beige |Black, White or |Green |Beige |Green |Beige |Beige |
| | |Beige | | | | | |
|Arctic Blue |Silver |Black, White or |Blue |Red |Blue |Beige |Red |
| | |Beige | | | | | |
| | | | |Beige |Blue |Beige |Beige |
|Venetian Red |Beige |Black, White or |Red |Red |Red |Beige |Red |
| | |Beige | | | | | |
| | | | |Beige |Red |Beige |Beige |
|Polo White |Silver |Black, White or |Red |Red |Red(1st des) |White (1st des) |Red |
| | |Beige | | |White(2nd des) |Beige (2nd des) | |
| | | |Silver |Beige |White |Beige |Beige |
|Inca Silver |Imperial Ivory |Black or White |Silver |Red |Silver |Beige |Red |
| | | | |Beige |Silver |Beige |Beige |
*Front fender depression is also available painted body color.
|Interior Colors and Fabrics |
|Area |Material |Trim Combination |
|Seats |Cushion |Waffle Pattern Vinyl |Red |Beige |
| |Backrest |Waffle Pattern Vinyl | | |
| |Cushion Bolster |Leather Grain Vinyl | | |
| |Backrest Bolster |Leather Grain Vinyl | | |
|Sidewalls |Top Roll |Leather Grain Vinyl |Red |Beige |
| |Upper Panel |Waffle Pattern Vinyl |Red |Beige |
| |Lower Panel |Leather Grain Vinyl |Red |Beige |
| |Arm Rest |Leather Grain Vinyl |Red |Beige |
| |Decorative Molding |Metal |Bright |Bright |
| |Scuff Pad |Textured Metal |Bright |Bright |
|Cowl Side Kick Panels | |Waffle Pattern Vinyl |Red |Beige |
|Windlace | |Leather Grain Vinyl |Red |Beige |
|Floor Covering | |Carpet |Red |Copper |
|Top Storage Well | |Paint |Red |Beige |
|Rear Compartment |Mat |Rubber |Red |Black |
| |Trim Board |Composition Board |Red |Beige |
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