Can anyone help me with how to identify which 455 I have as for as horsepower rating, compression etc. I heard there was a casting number on the block but not sure where to look and how to identify what number goes to which 455 specs.

its a 1970 as for as I know.

Thanks

 

Unfortunately, there is no way to tell without disassembling the engine and checking valve size, cam profile, and compression ratio. Olds did use a paper tape on the oil fill tube that indicated the engine configuration and HP, but these are usually long gone and since repros are available I certainly wouldn't trust one that looked relatively new.

 

There is a small vertical pad on the drivers side of the engine, just below the head surface, or deck surface, that has some numbers, which will tell you what year it is. There is a letter above the water pump or a couple letters, which will id it and finally some on the rear of the block. The power steering bracket may hinder your search, but its the best way to know the year. If it has the original oil filler tube, it is stamped as well.. not just tagged. Clean and scrape, or sand, and you should find the stamping. All those numbers are easily traced and verified.

 

I can't believe that they'd use a paper tag as the only way to accurately ID the engine for factory HP/torque/compression ratings. If there is any other way without tearing the engine apart, I'd love to know it as well.

I have the casting number from mine, all it told me was the year range and displacement.

 

without knowing for certain which carb and distributor came on it, and original, you have little chance of knowing. If original, the intake could tell you, the oil pan both if are toronado, the other mentioned parts would relate to the set up inside the engine. IE, comp ratio being the biggest determining factor.
Otherwise, those locations I mentioned are the only way unless you disassemble. The stamping into the metal of oil filler tube, stamping on side of block just below head, and also above water pump, and rear of engine block.

 

If it has a big letter "E" on each cylinder head,then it could be a 70 455,or at least you have 70 cylinder heads.Unless it has been rebuilt or modified,the 40+yr old engine does not make as much power as what it was rated back then.ALL 455's have 396021 F next to the oil fill tube,to identify it as a 455 block.Some later ones have 396021 Fa.

 

Easily traced and verified? Meaning what? None of those numbers will identify which version of the 455 that it is.
As Joe said, the only external identification was the paper tag. Period. If the engine was never apart, and it is a 1970 455, the only other way you'd know what you have is if you have F heads. Other than that rare combo, they're all various versions of E head engines.