I met this guy a few days ago. He said he had an engine out of a 70 SX. The casting number is 396021F. He also said it had C heads. I haven't seen the engine yet so I'm not sure about the heads. I would be deeply grateful if some one can help me. Thanks JIM

 

That is the block casting number for a 455 engine. A 1970 SX would have had E heads from the factory. C heads were used from 1967-1969 and are very good heads so someone could have swapped them at some point.

You can check the VIN pad on the block to see the year of manufacture.

First number (3) =Olds division
Second number = year of manufacture
Third (letter) = manufacturing plant
Four to six = VIN derivative

 

Kenneth, Thank you for your prompt answer. I appreciate that. Like I said haven't seen the motor. Will get with the guy tomorrow and look. He thinks it is a rare engine and even more rare heads. I don't think so. Will let you know. Thanks again. JIM

 

And don't let him give you the "this block has the high nickel content" either. Never been confirmed to be true.

 

Actually there was a thread that proved it was not true. See post 34
https://classicoldsmobile.com/forums...ur-engine.html

 

Rare is all in a person's perspective. They aren't made any longer so does that make the engine and heads rare?

C heads are probably the most common Olds BBO heads as they were manufactured for more years than the other letter heads, but again, other than the later J heads they're all about the same.

As for the 455 engine itself, even if it was from a 70 SX it's just a 70 455 engine that is about equivalent to any other 68-70 365 horse 455. Not really anything special about it.