6272990 Heads

[Patrick C.]

So I just picked up a pair of these 6272990 heads. They have 2.25/1.88 valves and are complete and rebuilt. My question is concerning the date code. My understanding is that the 1970's date codes were six digits. Mine are 5 digit. E238. Is this normal? Other posts say these heads weren't available 'til the 70's.

[Joe L.]

Re: 6272990 Heads

So I just picked up a pair of these 6272990 heads. They have 2.25/1.88 valves and are complete and rebuilt. My question is concerning the date code. My understanding is that the 1970's date codes were six digits. Mine are 5 digit. E238. Is this normal? Other posts say these heads weren't available 'til the 70's.

Patrick-------

The GM casting 6272990 cylinder heads were never used in any PRODUCTION application that I am aware of and were certainly never originally used for any Corvette application. They are a cast iron, open chamber design and were a SERVICE-only part. They actually have 2.19" intake valves and 1.88" exhaust valves. They were introduced in the 1970's. They were intended for SHP/HD applications and are roughly a cast iron equivalent to 1969+ SHP/HD aluminum cylinder heads. They were once available under GM PART #6260482 but have been discontinued for quite some time now.

The 2 digit year casting date was pretty much a "phenomenon" of the old Tonawanda cast iron foundry. By the time these heads were manufactured I believe that big block cast iron castings had been transferred to the Defiance, OH foundry which usually used a 1 digit year. So, these heads were likely cast in 1985 or 1995. Inasmuch as these heads were never used in PRODUCTION, the casting date really is of little significance.