oldsmobile 76 cutlass salon is it a true 455 or something else

[Aisha]

I have a 76 cutlass salon, the engine stamp says 396021F and the heads are 389395 part # 39410B

so....is my motor a true 455? the heads are for a 425? I am confused 

I have been rebuilding this engine with tons of difficulty, i order parts for a 76 salon but then the parts do not fit, its been alot of trial and error because i cannot get certain parts, like timing belts/chain, I got a new harmonic balancer and a cam, but they don't seem to fit, so i am spending too much time measuring and finding parts, any advice

Edited November 16, 2022 by Aisha
missed a number (see edit history)

[joe_padavano]

The block is what determines what motor it is. 396021 F is a 455 block casting. That casting number was used from 1968 through at least 1974 (despite what you may read on the interwebs). You can tell the exact model year of the block by looking at the VIN derivative stamp. The second character is the model year. In this example, "2" in the second position indicates the 1972 model year.

 

 

389395 heads are from the 1966 model year. Obviously they are not original to that block. Any 1964-1990 Olds V8 head will bolt to any 1964-1990 Olds block. Those are not bad heads. In any case, the heads (certainly) and the possibly the block are not original to that car. In the 1976 model year, the fifth character of the car's VIN will tell you what engine was installed when the car left the factory.