I am looking to get a 455 block to put in a 442. I know that there are F blocks and Fa blocks, and maybe other letters too that I don't know of. The guy I might buy the block from has no idea what year or model car the engine came out of, so it could be anything from a 68 or later I think. What are all the differences between the different letter 455s (bore, stroke, compression ratio, etc.) that I would need to know for my engine build? and are there any letter blocks that I should steer clear of if I'm looking to make a lot of power? I'd be buying the entire assembled engine, but all I'd really be using is the block and maybe the crank.

Thanks!

 

The bore and stroke are the same on all 455s. The casting letter won't tell you anything, since the same castings were used for multiple years. The reality is that you really can't tell the CR from anything on the outside (with the exception that 1971-newer will be low compression.