Will a 400 small block w/ 400 turbo trans from a '72 Pontiac Grand Prix fit right into an '88 Firebird?

Q: This IS a small block 400. Fact.

A: If it's an original 1972 Grand Prix 400ci engine, it's not a Chevy block, it's a Pontiac block. They were physically larger than a Chevy small block 400. All Pontiac blocks were physically the same size regardless of the cubic inch displacement. The differences were the bore and stroke but physically they were all the same size from a 287 to a 455. They were larger than a Chevy small block but smaller than Chevy big block. Your 1988 firebird would be built with a Chevrolet small block based V8 which as I stated is physically smaller than the older Pontiac engine. It would not be a direct bolt in job. It would require a lot of modification. Can it be done ? Of course it can with the right mods. You stated that yours has a small block 400 (assuming you meant the Gran Prix) so it may not be the original engine and may have already been swapped. Pontiac did not start using Chevy engines until 1977. BTW, in 1972 the bolt pattern for transmissions was the same for Buick , Olds, Pontiac, and Cadillac but Chevrolets was different .

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