I have a 71 chevy cheyenne C10- It came with a factory 396 BB-


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fumanchu

I have a 71 chevy cheyenne C10- It came with a factory 396 BB-

This is the original numbers matching motor, and the glovebox also states it has a 396. I am rebuilding this motor, but it states Hi Perf and Pass on the block and heads. I am told this is a passenger car motor. Every parts dealership (autozone, advanced, Oreilleys, etc) tells me Chevy did not put a 396 in a 71 C-10, only 402s. So- what have I got? Is it rare, special order, or an odd duck? How many 71's had a 396 Vs a 402? I bought this truck from the original owner (in his 80s) and he swears this is all original. Since it still had two spare mud tires in the back from 1972 (never used), I believe him. Ideas?

posted: March 7, 2012

Answers (3)

retiredpartsman

kendalasmith

fumanchu

Well guys, I found the answer- my truck 396 was actually a 402, and what usually happened was if a 396 cylinder wall got damaged in assembly, they bored it .30 over and put it in a truck. This is why the block says 396/Pass hi Perf. I am told those were built for a chevelle SS. (The numbers do match my truck) .To blow everyones mind further, I have found out that a 396 has so much metal in it that it can be bored to.... a 427! crazy! I mic'ed mine and it was in fact a 402 like you said, now a 408 due to some wear on the cylinder walls. I guess I have a lot of room left before I get to 427...... Thanks for the answers guys!

posted: March 22, 2012