C3 (1979) Intake Manifold Date Codes

[Paul L.]

For the #14007378 aluminum intake manifold, where are the date codes located and how does one interpret them? Also, how close should the date on the manifold be to that of the engine block?

[Joe L.]

Re: C3 (1979) Intake Manifold Date Codes

Paul------

Usually, on this genre of aluminum manifolds the date is found on the UNDER side of the manifold. Often it is found in the area under the oil splash shield. The date is usually month, day, and year in the following format for a manifold dated February 15, 1978-----"2.15.78".

Manifold should be dated about 3 weeks to 6 months prior to engine build date. 3 to 8 weeks would be most typical of PRODUCTION.

[Paul L.]

Re: C3 (1979) Intake Manifold Date Codes

Joe,
No numbers under the splashshield. On top I find 14007378 (medium font), GM 1 F (large font) and 11/15/1 (small font). On the bottom outside of the splashshield I find H 378.

[Joe L.]

Re: C3 (1979) Intake Manifold Date Codes

Paul-----

I'd say that the "11/15/1" is the date, then. This must mean that it was cast on November 15, 1981 or 1991. So, it was likely originally a SERVICE manifold. A lot of these manifolds were sold by GM in SERVICE as a "hi-performance" replacement for cast iron, EGR-type Q-Jet manifolds.

[Paul L.]

Re: C3 (1979) Intake Manifold Date Codes

Joe,
I never thought of that although I should have. Just out of curiousity I checked the GM parts database last week and the iron and aluminum intakes are still available for 1979. The casting numbers are not specified, however. And the prices are outrageous. The cast iron was about $425.00US.

[Paul L.]

Re: C3 (1979) Intake Manifold Date Codes

Here is a pic link.