Question for Joe Lucia.....please.

[Warren F.]

Joe:

My question concerns the 1970/1971 LS-6 aluminum intake manifold used on the Chevelle/Corvette during this time.

The casting # on the manifold is 3963569. There are two variations I know of. The more common one has no numbered cylinder intake runners, this manifold seems to have been the production version, usually seen on all Chevelles/Corvettes. The other version has cast intake runner cylinder numbers (1357 & 2468). This version is not near as common to find.

Can you tell me when this 2nd version came into being or how long either version of this manifold was produced after production ceased for it's application in 1971?

Any info you might want to conjecture would also be fine with me, I really appreciate your assistance with everyones inquiries on this board!

[Joe L.]

Re: Question for Joe Lucia.....please.

Warren------

Yes, there were the 2 different versions of the GM #3963569 manifold, as you described. The version without the runner numbers was used, generally, for the 1970 model year. It was used on 1970 Chevelles with LS-6 as well as 1970 Chevelles, Camaros, and Novas with L-78.

The version with the numbers on the runners was used, generally, for the 1971 model year. It was used for Corvettes with LS-6. They were supposed to be installed in 1971 Chevelles with LS-6, too, but none were actually built.

It's very possible that some of the "non-numbered runner" intakes were used at the very beginning of the 1971 model year, too. I have no way of documenting that one way or the other.

The 1971 Corvette manifold was known as GM PART #3977609. The 1970 LS-6 and L-78 manifold may have been the same part number, too, At least, I haven't been able to determine any other part number that the 3963569 casting was used for.

The GM #3977609 manifold was discontinued from SERVICE in July, 1983. Most of the non-numbered examples of the 3977609 that are around are likely PRODUCTION pieces from the 1970 models that originally used them and those SERVICE pieces sold prior to about 1971. The examples with numbered runners are either PRODUCTION pieces from 1971 Corvettes with LS-6 or SERVICE pieces sold until the time of discontinuation of the part. While the part was discontinued from SERVICE in July, 1983, I don't know when the actual manufacture of the manifold ceased. I would expect well before 1983, though.

[Warren F.]

Thankyou Joe. *NM*