NCRS Help - LT-1 cylinder heads

[billla]

Folks, I really don't deal in restoration work any more but I'm selling a set of heads and I've been told there's no way they're correct for an LT-1...even though all the data I have says they are.

I'm being told that the casting numbers need to be within 6 months of the car manufacture date?

These are casting number 3927186. Date Codes H-15-8 (August 15th, 1968) and K-6-9 (November 6th, 1969).

Guidance appreciated - the last thing I want to do is misrepresent these.

[gbvette62]

The 3927186 casting was used in 69 for 300 & 350 horse engines (3927187 was also used with 350 horse & 3947041 with the 300). 186 is listed for use with the 300, 350 & 370 (LT-1) horse engines in 1970. 3973414 was also used on 70 LT-1's.

Being 11 months apart (Aug. 68 to Nov. 69), it's doubtful that these heads originally came as a pair on the same engine. Heads normally carry a casting date within a day or two of each other when installed on an engine. The 68 head, though probably installed in a 69 car, would not have been on an LT-1 as production of LT-1's (even as a crate engine) didn't begin before late 1969. The Nov. 69 head may or may not have ended up on an LT-1. LT-1's weren't installed in Corvettes (or Z-28's) before Jan. 70. 69 Corvette production ran through Dec. 69, so a Nov. 6, 69 head could have very possibly ended up on a 69 300 or 350HP Vette or a 70 300, 350 or LT-1 Vette (or a 70 Full Size, Chevelle, Nova or truck as 70 model year production of these began in July or August 69).

The 6 month "rule" used by the NCRS refers to what they will consider an exceptable date on a part for judging (up to 6 months prior to the car's build date). As stated above though, heads would normally be expected to be no more than a few days apart.

I hope this makes sense, and helps.

[billla]

Very complete - thank you!