1967 BIG BLOCK OIL CAP

[Louis F.]

I'd like to restore a 1967 big block oil cap.For judging purposes, what is the accepted finish.Is black accepted without question or must it be an olive colored plating.Are both finishes accepted?
Also,I've seen oil caps with multiple configurations with reference to the notch/notches on the ears.Is only one configuration accepted or can there be more then one. As always thanks for your help.

[Joe L.]

Re: 1967 BIG BLOCK OIL CAP

Louis------

I can't advise you as to judging considerations. However, I can tell you this much:

The GM specifications for the big block oil filler cap, GM #3856959, called for the cap to be finished in black enamel. This cap was used in PRODUCTION for 1965-67 Corvettes with big block engines (except 1967 with L-89) and it was NEVER available in SERVICE from GM. Stant was the manufacturer and the cap was, at one time, available from them as a SERVICE item. Examples of these caps that I have seen in Stant packaging were finished in black enamel as the GM prints specified. Incidentally, the cap initially and for quite some time thereafter available in SERVICE from GM was a similar cap with a plain finish and of GM #3835665.

In 1966 the filler cap for Corvette (and, other) SMALL blocks became GM #3881834. This cap is, of course, of a completely different configuration and design from the big block cap. However, the finish for the 3881834 was specified by GM to be "black zinc". It is this finish that can exhibit the slightly "greenish" coloration.

Some of the "theoretically original" oil filler caps that I've seen on 65-67 big blocks do appear to have this greenish coloration. Consequently, I believe that these were finished in the "black zinc" finish and contrary to what the GM specifications called for. That may have been handled by some "off-spec" approval that Stant obtained from GM, perhaps to consolidate finishing operations for the big block and small block caps. So, while it's possible that some big block caps were finished with the "black zinc", I don't know if all were. As I say, the black zinc is contrary to what the specifications for the big block cap called for.