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[pic][pic]PATH:  Fuel System > Carbureted Fuel System > Carburetors > Overhaul > Main Body

Main Body

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|Removing the accelerator pump discharge check ball |

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|Accelerator pump discharge assembly |

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1. Remove the air cleaner anchor stud.

2. Remove the secondary diaphragm link C-clip.

3. Invert the carburetor and remove the throttle body attaching screws and lockwashers. Lift off the throttle body and discard the gasket.

4. Remove the choke housing cap and gasket.

5. Remove the 3 choke housing retaining screws and pull the housing from the main body while pushing the choke rod out of the retainer on the choke housing shaft lever.

6. Remove the choke housing shaft nut, star washer, spacer, lever, fast idle cam spring, spring perch and fast idle cam.

7. Remove the over center spring and choke housing shaft.

8. Remove the choke diaphragm cover screws and separate the diaphragm cover from the diaphragm.

9. Remove the diaphragm spring.

10. Slide the diaphragm and shaft assembly out as far as it will go and remove the choke modulator spring retaining clip. Remove the modulator spring, spring seat and spring perch.

11. Slide the diaphragm assembly out of the choke housing. Remove the nylon choke modulator bushing from the housing.

12. Snap the choke rod from the choke shaft lever retainer.

13. Pull the choke rod up and remove it from the dust seal.

14. Remove the choke plate from the choke shaft and slide the shaft and lever from the air horn.

The retaining screws are staked. If the staking is excessive, it will have to be filed off. Be careful to avoid damage to surrounding parts when filing.

15. Remove the 3 screws and remove the secondary diaphragm and O-ring from the main body.

The housing must be removed before the cover can be removed.

16. Remove the diaphragm housing cover, then remove the spring and diaphragm, and the check ball from the housing.

17. Remove the accelerator pump discharge nozzle screw. Lift the pump discharge nozzle and gaskets out of the main body.

18. Invert the main body and let the accelerator pump discharge check ball fall into your hand.

Your carburetor may use a needle instead of a ball.

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|Secondary diaphragm assembly |

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|Choke modulator spring installation |

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|Choke lever over center spring installation |

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|Choke housing linkage installation |

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1. Drop the accelerator pump check ball into its well. LIGHTLY tap it into place with a brass punch.

2. Install the lower gasket, accelerator pump nozzle and upper gasket in the main body and install the retaining screw. Torque the screw to 27-43 inch lbs. (3-5 Nm).

The accelerator pump assembly must be installed before any other main body parts.

3. Install the spring in the secondary diaphragm housing cover. Drop the check ball into the vacuum port and position the secondary diaphragm in the housing. Make sure that the diaphragm is seated evenly and the vacuum opening is aligned. Install the cover and tighten the attaching screws. Torque the screws to 13-17 inch lbs. (1.5-2 Nm).

The diaphragm housing must be removed from the main body to install the cover.

4. Place the O-ring on the secondary vacuum tube in the secondary housing. Place the diaphragm in position on the main body and install the lockwashers and screws.

5. Install the choke rod seal in the main body. Slide the bottom of the choke rod through the seal.

6. Install the choke rod retainer onto the choke shaft lever.

7. Slide the choke shaft into the air horn and snap the top of the choke rod into the retainer on the choke shaft lever.

8. Slide the nylon choke modulator bushing onto the choke thermostat lever.

9. Install the choke modulator, spring perch, spring, spring seat and retaining clip. Position this assembly into the choke housing and rotate the choke modulator bushing until it slide securely into place.

10. Align the diaphragm vacuum hole with the vacuum tube in the choke housing.

11. Install the choke diaphragm spring and cover. Torque the cover screws to 13-17 inch lbs. (1.47-1.92 Nm).

12. Install the choke housing shaft and lever assembly, and the over center spring.

13. Install the fast idle cam, spring perch, spring, lever, spacer, star washer and nut.

14. Install the O-ring on the vacuum tube.

15. Position the choke housing assembly onto the main body and push the choke rod onto the retainer on the choke housing shaft lever. Install the choke housing screws. Torque the screws to 20-30 inch lbs. (2.25-3.34 Nm).

16. Install and adjust the choke cap and gasket. Torque the cap screws to 16-18 inch lbs. (1.8-2 Nm).

17. Invert the main body and position the throttle body and gasket on the main body. Slide the secondary diaphragm rod onto the operating lever as the throttle body is positioned. Install and tighten the screws and lockwashers. Torque the screws to 39-52 inch lbs. (4.4-5.9 Nm). Place the retainer on the diaphragm rod.

18. Install the air cleaner stud.

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[pic][pic]PATH:  Fuel System > Carbureted Fuel System > Carburetors > Overhaul > Overhaul Kits

Overhaul Kits

Carburetor overhaul kits are recommended for each overhaul. These kits contain all gaskets and new parts to replace those which deteriorate most rapidly. Failure to replace all of the parts supplied with the kit (especially gaskets) can result in poor performance later.

Most carburetor manufacturers supply overhaul kits of three basic types:

Minor Repair Kits:

• All gaskets

• Float needle valve

• Volume control screw

• All diaphragms

• Spring for the pump diaphragm

Major Repair Kits:

• All jets and gaskets

• All diaphragms

• Float needle valve

• Volume control screw

• Pump ball valve

• Main jet carrier

• Float

• Other necessary items

• Some cover hold-down screws and washers

Gasket Kits:

• All gaskets

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[pic][pic]PATH:  Fuel System > Carbureted Fuel System > Carburetors > Overhaul > Preliminary Instructions

Preliminary Instructions

Efficient carburetion depends greatly on careful cleaning and inspection during overhaul since dirt, gum, water or varnish in or on the carburetor parts are often responsible for poor performance.

Overhaul the carburetor in a clean, dust free area. Carefully disassemble the carburetor, referring often to the exploded views. Keep all similar and look-alike parts segregated during disassembly and cleaning to avoid accidental interchange during assembly. Make a note of all jet sizes.

When the carburetor is disassembled, wash all parts (except diaphragms, electric choke units, pump plunger and any other plastic, leather, fiber, or rubber parts) in clean carburetor solvent. Do not leave the parts in the solvent any longer than is necessary to sufficiently loosen the dirt and deposits. Excessive cleaning may remove the special finish from the float bowl and choke valve bodies, leaving these parts unfit for service. Rinse all parts in clean solvent and blow them dry with compressed air or allow them to air dry, while resting on clean, lintless paper. Wipe clean all cork, plastic, leather and fiber parts with clean, lint free cloth.

Blow out all passages and jets with compressed air and be sure that there are no restrictions or blockages. Never use wire or similar tools to clean jets, fuel passages or air bleeds. Clean all jets and valves separately to avoid accidental interchange.

Examine all parts for wear or damage. If wear or damage is found, replace the defective parts. Especially, inspect the following:

1. Check the float needle and seat for wear. If wear is found, replace the complete assembly.

2. Check the float hinge pin for wear and the float(s) for dents or distortion. Replace the float if fuel has leaked into it.

3. Check the throttle and choke shaft bores for wear or an out-of-round condition. Damage or wear to the throttle arm, shaft or shaft bore will often require replacement of the throttle body. These parts require a close tolerance of fit; wear may allow air leakage, which could affect starting and idling.

Throttle shaft and bushings are not normally included in overhaul kits. They can be purchased separately.

4. Inspect the idle mixture adjusting needles for burrs and grooves. Any such condition requires replacement of the needle, since you will not be able to obtain a satisfactory idle.

5. Test the accelerator pump check valves. They should pass air one way, but not the other. Test for proper seating by blowing and sucking on the valve. Replace the valve as necessary. If the valve is satisfactory, wash the valve again to remove moisture.

6. Check the bowl cover for warped surfaces with a straightedge.

7. Closely inspect the valves and seats for wear and damage, replacing as necessary.

8. After the carburetor is assembled, check the choke valve for freedom of operation.

After cleaning and checking all components, reassemble the carburetor, using new parts and referring to the exploded view. When reassembling, make sure that all screws and jets are right in their seat, but do not overtighten, as the tip will be distorted. Tighten all screws gradually, in rotation. Do not tighten needle valves into their seats; uneven jetting will result. Always use new gaskets. Be sure to adjust the float level.

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[pic][pic]PATH:  Fuel System > Carbureted Fuel System > Carburetors > Overhaul > Primary Fuel Bowl And Metering Block

Primary Fuel Bowl And Metering Block

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|Exploded view of the Holley 4180-C 4-bbl. carburetor |

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|Removing the main jet |

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|Removing the power valve |

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|Removing the float shaft retainer clip |

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1. Remove the fuel bowl and gasket and metering block and gasket. Discard the gaskets.

2. Remove the pump transfer tube from the main housing or metering block and discard the O-rings.

3. Remove the fuel line tube and discard the O-ring.

4. Remove the main jets.

5. Remove the power valve and gasket.

6. Remove the fuel level adjustment lockscrew and gasket. Remove the adjusting screw and the inlet needle and seat assembly. The needle and seat assembly is a matched set and must be replaced by a matched set. Discard the inlet gasket.

7. Remove the float shaft retainer clip and slide the float off the shaft. Remove the spring from the float.

8. Remove the baffle plate from the float bowl.

9. Remove the fuel level sight plug and gasket.

10. Remove the fuel inlet fitting, gasket and filter screen.

11. Invert the float bowl and remove the accelerator pump cover, diaphragm and spring. The pump inlet check ball should not be removed.

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|Primary fuel bowl assembly |

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1. Place the accelerator pump diaphragm spring and diaphragm into the accelerator pump chamber. The diaphragm must be positioned so that the large end of the rivet will be against the pump cover arm.

2. Install the cover and tighten the screws finger-tight. Make sure that the diaphragm is center, depress the diaphragm with the arm and tighten the screws.

3. Install the filter spring, filter, gasket and inlet fitting. Torque the fitting to 22-26 ft. lbs. (30-35 Nm).

4. Install the fuel level sight plug and gasket.

5. Slide the baffle plate onto the ridges in the fuel bowl.

6. Install the float spring on the float and slide the float onto the shaft. Make sure that the float spring is centered between the ridges on the boss. Install the E-clip.

7. Coat a new O-ring with petroleum jelly and slide it onto the needle and seat assembly.

8. Position the needle and seat assembly into the float bowl.

9. Position the adjusting nut gasket and nut on the needle and seat assembly. Align the flat on the inside diameter of the nut with the flat on the outside diameter of the needle and seat. Install the lockscrew and gasket.

10. Perform a preliminary (dry) float adjustment, described above.

11. Install the power valve and gasket in the metering block. Torque the power valve to 9-12 ft. lbs. (12-16 Nm).

12. Install the pump transfer tube and new O-rings in the metering block.

13. Install the jets in the metering block. Torque the jets to 18-20 inch lbs. (2-2.25 Nm).

14. Place the metering block gaskets on the dowels on the back of the block. Place the block and gasket on the main body. Place the fuel bowl gasket on the metering block. Place the retaining screws and new compression gaskets in the fuel bowl. Place the bowl on the metering block and tighten the retaining screws to 50-60 inch lbs. (5.65-7 Nm).

15. Coat the fuel line tube O-ring with petroleum jelly. Place the O-ring against the flange on the end of the fuel line tube. Install this end into the recess the the primary bowl. make sure the O-ring isn't pinched.

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[pic][pic]PATH:  Fuel System > Carbureted Fuel System > Carburetors > Overhaul > Secondary Fuel Bowl And Metering Body

Secondary Fuel Bowl And Metering Body

1. Install the fuel level sight plug and gasket.

2. Install the baffle plate in the float bowl.

3. Install the float spring on the float and slide the float onto the shaft. Make sure that the float spring is centered between the ridges on the boss. Install the E-clip.

4. Coat a new O-ring with petroleum jelly and slide it onto the needle and seat assembly.

5. Position the needle and seat assembly into the float bowl.

6. Position the adjusting nut gasket and nut on the needle and seat assembly. Align the flat on the inside diameter of the nut with the flat on the outside diameter of the needle and seat. Install the lockscrew and gasket.

7. Perform a preliminary (dry) float adjustment, described above.

8. Using a clutch-type screwdriver, install the metering body, plate and gaskets.

9. Coat the fuel line tube O-ring with petroleum jelly and position it against the flange on the fuel line tube.

10. Install the fuel bowl on the main body, guiding the tube into the recess in the bowl. Install the retaining screws and new compression gaskets. Torque the screws to 50-60 inch lbs. (6-7 Nm).

11. Perform all necessary adjustments described above.

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|Secondary fuel bowl and metering plate assembly |

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[pic][pic]PATH:  Fuel System > Carbureted Fuel System > Carburetors > Overhaul > Secondary Fuel Bowl And Metering Plate

Secondary Fuel Bowl And Metering Plate

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|Removing the secondary metering plate |

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1. Remove the fuel bowl.

2. Using a clutch-type screwdriver, remove the metering body, plate and gaskets. Discard the gaskets.

3. Remove the fuel level adjustment lockscrew and gasket. Remove the adjusting screw and the inlet needle and seat assembly. The needle and seat assembly is a matched set and must be replaced by a matched set. Discard the inlet gasket.

4. Remove the float shaft retainer clip and slide the float off the shaft. Remove the spring from the float.

5. Remove the baffle plate from the float bowl.

6. Remove the fuel level sight plug and gasket.

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