I purchased a 72 Vette base engine coupe a day before leaving on a 3 month trip, which is now winding down. My question is on the cylinder head casting numbers. The numbers are 3973487, and within the month build date, compared to the plate riveted onto the hinge pillar, however, I've been told over the internet that the casting number(s) should also have an "X" after the number, is that correct??  The person I bought the car from had it for 15 years, and not being a car person, never asked the seller he bought from whether everything was correct, so I'm not sure if the heads have been replaced or they are the original 72 heads. The engine needs to be rebuilt, and before spending money on the wrong parts I'd like to know what I'm dealing with. 

Depends on the actual build date of the engine. If the engine has a build date late in the model year, the heads should have an "X" at the end of the casting #.

My car was built in Dec 71, so to me that is an "early" build, but I do not know if that really is correct or not. At what point would a car be considered an "early" verses a "later" production piece?

I'd say you have an early build date.     My Feb 2 build date looks weird.

Looking through the oil cap upside down, it has a stamped slash before and after the 3973487 and below that is I(or 1) 22 - 71, not sure what those mean.  I don't see an X.  My engine casting is Dec 17, 71 and my engine build date is Jan 17.  Don't know if it still has the original heads.

NCRS judging manual says they don't judge casting numbers or dates.




|UPDATED|1/19/2017 11:16:32 AM (AZT)|/UPDATED|

Dec build date would be considered "early", in this case. So your heads technically would not have the "X" in the casting. If you can get the valve covers off, you can check the date code, and see if it jives with the engine build date. Heads can be dated before, or even the same as the engine casting date, but should NOT be dated AFTER the engine build date.