1971 Olds Cutlass 350c.i.d. build - Oldsmobile Club of ...



1971 Olds Cutlass 350c.i.d. build Technical Article part 1This project and technical article will cover all aspects of diagnosing, removal, rebuilding, and re-installation of the four barrel 350 c.i.d. engine and turbo 350 transmission original to the 1971 Cutlass belonging to new member Frank Gattuccio. There will be photos to accompany this process to better portray some of the steps that will be taken during this project and I encourage any of you who may be embarking on a similar project in the near future to email or call me with any questions you may have.To begin with this tech series, we start with the diagnosis which began a couple of months back when Frank brought his car to me to listen to a deep rattle sound coming from the front of the engine. This was a sound that when described over the phone, first lead me to consider a failing timing chain assembly. Once I heard the noise in person, it was quite evident that the sound was deeper and potentially more severe so I removed his electrical oil pressure sensor and attached a mechanical diagnostic gauge to the motor. What we found was between 0-5psi of oil pressure at idle, well below the 25psi minimum recommendation by Oldsmobile or most engine builders.The decision was made to remove the engine and trans for a rebuild as it was suspected that the motor had never been rebuilt and there was no real history on service work on the car in general including the trans. What we found as we ( with assistance from new member Thomas Jones ) removed and stripped down the engine was quite surprising regarding the overall condition of the engine and trans and how well the car still ran.The noise we heard was actually the harmonic balancer wobbling on the snout of a very worn crankshaft, which meant both components would need to be replaced. We also found a caved in oil pan, bent oil pump pickup, clogged oil pump pick up screen ( old timing chain debris ), well worn original bearings, leaking rear main seal, excessive sludge build up primarilly in the lifter valley, worn out rocker stands, one broken piston ring, baked hard valve cover gaskets, cracked oil filter housing, broken motor and trans mounts, caved in trans pan and a poorly done rebuild job on the trans some time in the past.You can imagine ours and Frank’s surprise that the car still ran as well as it did. So now we needed a plan to rebuild both the motor and the trans, deciding what the primary use of the car would be so the appropriate component decisions could be made. It was decided this would be a street cruiser, built with a bit more horsepower but with drivability and fuel economy still in mind. The goal would be to build a 370hp+ engine, based loosely on the W-31 platform, using easily acquired aftermarket parts to improve durability, and upgrade the transmission and torque convertor to handle the added power and improve driveability. ................
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