C3 Gasker sealer for gas cap gasket

[Guest]

What is the correct sealant to use on the paper gasket on a 1969 gas cap? I have the checked the archives, judging manual and other manuals and can't find anything.

Thanks,
Allen

[Jim T.]

Re: C3 Gasker sealer for gas cap gasket

Allen I have 68 and 70 original gas caps on mine and they have rubber seal not paper gasket.

[Guest]

Re: C3 Gasker sealer for gas cap gasket

Jim,

I'm just going by the judging manual that says, "Gasket on the original is paper, while service replacements are rubber." And my car got deducted for it last time it was judged so I am replacing it with a paper gasket.

Allen

[Terry M.]

Re: C3 Gasker sealer for gas cap gasket

My original 1970 gas cap has a paper gasket. There is no visible glue holding it on, so I can't tell you what is used. That said, I am a real fan of 3M Super Weatherstrip Glue (commonly referred to as "yellow snot"). If it were me I would use the 3M product carefully, not in the usual Corvette fashion.

[Chuck S.]

Re: C3 Gasker sealer for gas cap gasket

Allen, I remember my 70 cap having a paper gasket with no sealant being used; gasket was loose on the cap but retained by the closure ears.

[Guest]

THANKS to everyone for the help!!! NM *NM*

[Jim T.]

Re: C3 Gasker sealer for gas cap gasket

Perhaps I am thinking my locking gas caps have the rubber which I have been using for over 30 years. I will have to unbox my originals and look for this paper gasket.

[Jim T.]

Re: C3 Gasker sealer for gas cap gasket

Just did a inspection of my original bought off the showroom floor 70's sealed gas cap and it has a rubber black gasket. My original owner 68 also has a black rubber gasket. Is this unusual, why do I have rubber gaskets when others have paper gaskets? Terry is your original owner gas cap sealed and or vented?

[Terry M.]

Re: C3 Gasker sealer for gas cap gasket

Jim my original 1970 gas cap is stamped SEALED. I'll got to the garage and look, but I am 99.9% sure it has the paper gasket. The locking gas cap (which I purchased at the parts dept. on the day I took delivery of the car - Feb 28, 1970) gasket is rubber.

[Joe L.]

Re: C3 Gasker sealer for gas cap gasket

Allen, et al-----

1964-67 Corvettes used a VENTED gas cap with a cellulose fiber gasket (tan material). This cap was GM #3843576.

Very early 1968 Corvettes may also have used this cap. Most 1968 Corvettes used VENTED cap GM #3921689. I believe that this cap used a black, nitrile rubber seal.

1969 Corvettes used VENTED cap GM #3952708. This cap used a black, nitrile rubber seal. On original caps, the seal was not glued or otherwise affixed to the cap. On later SERVICE caps, the seal was attached to the cap with a neoprene solvent adhesive (an example of which is 3M Super Weatherstrip Cement). It is VERY difficult to discern the fact that the seal is affixed with cement, though.

1970 Corvettes used a SEALED cap of GM #3974743. I don't know much about this cap, but it would surprise me if it reverted to the use of a cellulose fiber seal. However, if Terry has an original cap and the cap has a cellulose fiber seal, then I guess this cap did use such a seal.

1971-74 Corvettes used a SEALED cap of GM #3994339. This cap used a black, nitrile rubber gasket. It also became the SERVICE cap for 1970 Corvettes when the GM #3974743 was discontinued from SERVICE in July, 1973.

[Guest]

Re: C3 Gasker sealer for gas cap gasket

I guess I'll put on the paper gasket with no sealant. And get a black, nitrile rubber gasket to swap out if the judge thinks it is the right one.

This is certainly all confusing sometimes.

Thanks,
Allen

[Joe L.]

Re: C3 Gasker sealer for gas cap gasket

Allen-----

I can't say what's necessary for judging. However, I can assure you that the information that I provided in my previous post is accurate. The original 1969 fuel cap used a black, nitrile rubber gasket. Very late 1969s could have used the 70-style sealed cap since they had integral pressure vacuum valves built into the fuel tank, but, as far as I know, they did NOT originally use the 70 cap----all 69s used the 1969 cap, GM #3956708. This cap became the SERVICE cap for 1963-68 Corvettes, too.

[Terry M.]

Maia Culpa

I guess the 0.1% got me. My 1970 gas cap has a black rubber gasket. Sorry for my mistake. BBBRRRRR it is cold out there.

[Joe L.]

Re: Maia Culpa

Terry-----

A few questions regarding this 1970 gas cap:

1) Does the perimter of the cap have the "scalloped" edge like the 63-69 caps or is it the smooth, perfectly round perimeter like the 71-74 caps?

2) Does the cap have the words "OPEN SLOWLY" embossed on the top in the "hemi-circle" below the "SEALED"?

3) Is the cap silver zinc plated like the 63-69 caps or does it have the dichromate (gold) overplate like the 71-74 caps?

[Terry M.]