Strange 318 Block

George Jets said
OK, good pictures.

Ran across one article that R meant runs on regular gas and, P means it runs on premium, I believe this was in the ID stamping areas and not the Block Cast in Casting Number though.

Need some time to think yet.

Can maybe do a grinder test on a standard block and the R Block and see which one sparks more. Regular Cast iron is supposed to have a real short spark trail.

Also can maybe come up with some type of hardness test on the rough cast areas of the outside cast areas of the block, simple sharp ground screw driver tip . . see if it diggs in easier on either of the blocks you might have around. Or some other test you might come up with.

Seem kind of odd that the only engine that comes up on the StockMopar.com chart for the Race Engine is that 318 Cast number you have. Probably some well experienced members that know what up with it for sure.

Fun looking into it.

I read that too somewhere, but yea I don't think it was with the casting numbers, I've yet to see any other block with this R cast on it, if anybody who has one could post a picture of it that would be great, and the hardness test would be tough, as the only other block I have is a slant 6 block that's been sitting outside for the last 4 years lol I absolutely don't have an X block, that block looks STRONG compared to the one I have sitting here, the only thing I think it could possibly be at this point is just a higher nickel content block, if anything.