1971 Fuel Cap Restoration - Recommendation(s)

[Leonard M.]

Re: 1971 Fuel Cap Restoration - Recommendation(s)

Ray, all the caps shown originally looked like yours or worse; I soaked them in Evaporust and that cleaned them up pretty good. They did look better after the soak and I should have sprayed them with satin clear to preserve that clean appearance.
Also, reading through the comments on caps, I have one cap that I am curious about. It is the round sealed cap with a Metal enameled/painted metal "open slow" tag and it has the Slant back.
The group picture shows 4 original scalloped sealed caps (the first 2 no tag caps are actually '71 caps with tag removed) with this round sealed cap. The red metal tag on the '71 cap closely resembles the tag on the round cap. I know that the original tags were made of aluminum and had a very durable "enameled" red background with silver letters. It may be difficult to see in the pictures, but the round cap has a metal tag, not a decal. Is it a Paragon reproduction or something else?

[Jerome P.]

Re: 1971 Fuel Cap Restoration - Recommendation(s)

Mark------


I think I was referring to the 1969 cap which was also SERVICE for 1963-68 after May, 1969. The primary difference between the 1964-67 cap, GM #3843576, is the gasket which is "paper" versus the 1969 cap which has a rubber gasket. I do not know how the 1968-only cap, GM #3921689, differed from either the 64-68 or the 1969 cap, GM #3952708. The 3843576 was discontinued in July, 1968 and replaced for SERVICE by the 3921689. The 3921689 lived a very short life and was discontinued and replaced by the 3952708 in May, 1969. I'd be very interested in seeing a photo of a known-original, 1968 only GM #3921689.

Below are photos of my original 1969 cap, a GM SERVICE #3953708, and a Stant replacement cap. The only difference I can see is the tiny Stant logo embossed on the underside of the cap.




The 1970 cap which may have been used into 1971 was GM #3974743. I now THINK that this was probably the same as the one pictured above but without the red label. It was discontinued from SERVICE in July, 1973 and replaced by the 1972-74 cap, GM #3994339. The 1971 cap was GM #3983384. I suspect it is the one pictured above. I don't know of a reproduction of the 3974743 or 3983384 cap although there may be one. The only visual difference I note between the 3974743, 3983384 and the earlier GM #3952708 is the embossment and the label. Of course, the 3974743/3983384 caps are functionally different from the 3952708 and, thus, not interchangeable.

The 1972-74 cap was GM #3994339. I don't have an original example of one of these caps but I do have a GM replacement as well as a Stant replacement. The GM cap has a very light chromate overplate while the Stant has a much heavier chromate overplate. These can easily be removed with a dilute acid solution. I'd be very curious to know how these caps differ from the originals other than, presumably, the embossed Stant logo on the underside.




One other "side issue": if one has a a 1963-69 Corvette with a GM SERVICE fuel tank purchased after 1970, it will incorporate an integral pressure-vacuum valve. GM instructs that when such a tank is used, the fuel cap should be changed to the sealed GM #3994339. I HIGHLY recommend that this be done. You can always install an original cap for judging.

Joe,

why is this cap recommended on tanks purchased after 1970?

[Joe L.]

Re: 1971 Fuel Cap Restoration - Recommendation(s)

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Joe,

why is this cap recommended on tanks purchased after 1970?

Jerry------


Those tanks have an integral pressure-vacuum valve. Therefore, they do not require a vented fuel cap. Fuel vapors released by a vented gas cap can waft into the passenger compartment. I know this for certain because I had it happen often in my original-owner 1969. When I replaced the tank and used a GM #3994339 cap as recommended by GM, this stopped.

Little did I know that I could have used a sealed cap with my original fuel tank. 1969's built after August, 1969 were originally built with fuel tanks with an integral pressure-vacuum valve but were fitted with the GM #3952708 vented fuel cap. These were the only Corvettes ever built with a fuel tank with an integral pressure-vacuum valve AND a vented fuel cap.

[Mike E.]

Re: 1971 Fuel Cap Restoration - Recommendation(s)

The red tag in the last picture looks like a reproduction to me. Its location on the cap is also atypical. The originals that I have are like your original (and Ray’s as well), with the top of the tag butting up against the curve.

[Ray K.]

Re: 1971 Fuel Cap Restoration - Recommendation(s)

Although I haven't personally seen Paragon's 1971 reproduction fuel cap, here's a picture of it that their showing on their web page. They describe it as: "Fuel filler cap, "Sealed" style w/correct logo and 8299 decal. this cap has the same scalloped edge as 1704 cap and is stamped "Sealed." It sell for $60.00. When Joe returns my restored cap, I'll take a run up to Paragon's and do a comparison . . . . .

[Joe L.]

Re: 1971 Fuel Cap Restoration - Recommendation(s)

The red tag in the last picture looks like a reproduction to me. Its location on the cap is also atypical. The originals that I have are like your original (and Ray’s as well), with the top of the tag butting up against the curve.

Mike------


The last cap looks like a GM #3994339 that has had a label added to it. I don't know that such a cap was ever used in PRODUCTION or available in SERVICE although I would not rule out the possibility. If it did ever exist, it did not have a unique part number as did the 1970 GM #3974743 versus the 1971 GM #3983384. These caps were the same except that the 3983384 had the red label.

REVISION:

I just noticed something important. Note that the GM #3994339 cap has the words "Open Slowly Caution" EMBOSSED on the cap. Note that the last cap shown in Leonard's photos, the apparent GM #3994339, with the red label appears to NOT have the embossment under the label. So, this was probably an early version of the 3994339. It certainly is not a 3994339 as we know it with the label added. It might be that GM gave the option of either a label or the embossment on the specs for the 3994339 and, initially, Stant chose to use the label. Or, it might be that GM changed the spec to add the caution warning after Stant had already produced a run of the caps so they added the label as an alternative.

If so, I would expect that early 1972's might have had the 3994339 with the label. Does the JG say anything about this? I don't have a copy of the latest JG.

[Leonard M.]

Re: 1971 Fuel Cap Restoration - Recommendation(s)

Mike, Looking carefully at the red tag on the round cap and comparing it to the tag on the original '71 scalloped cap, there is very slight differences as the size of the red area on the right and the fonts. So, that tag is Not the same as the GM one, but looks identical to the Paragon one.
Ray, That Paragon cap is very nice and I did not think that a scalloped "sealed" embossed car was reproduced, but the Big difference is that the ears on the handle are spot welded in reverse of the original.
Joe, Examining the round cap closely; the tag on the round cap is slightly different from the GM tag, it is a Slant replacement cap and looking to the right of the red label with magnification I can see "LY" embossed. So, I'd say it was a Slant replacement as you show with a reproduction label added later by an individual. I did not add the label and have no history on it as I bought it off ebay a couple years ago.

[James G.]

Re: 1971 Fuel Cap Restoration - Recommendation(s)

EVERY ORIGINAL CAP SHOWN has the spotwelded tabs pointing away from the SEALED debossing- the ones suspected as REPROS have the TABS pointing toward the SEALED debossing.

[Joe L.]

Re: 1971 Fuel Cap Restoration - Recommendation(s)

Mike, Looking carefully at the red tag on the round cap and comparing it to the tag on the original '71 scalloped cap, there is very slight differences as the size of the red area on the right and the fonts. So, that tag is Not the same as the GM one, but looks identical to the Paragon one.
Ray, That Paragon cap is very nice and I did not think that a scalloped "sealed" embossed car was reproduced, but the Big difference is that the ears on the handle are spot welded in reverse of the original.
Joe, Examining the round cap closely; the tag on the round cap is slightly different from the GM tag, it is a Slant replacement cap and looking to the right of the red label with magnification I can see "LY" embossed. So, I'd say it was a Slant replacement as you show with a reproduction label added later by an individual. I did not add the label and have no history on it as I bought it off ebay a couple years ago.

Leonard-----


I looked as best as I could to see if I could see any embossing, especially on the end you mentioned (because the embossment essentially extends from "notch to notch"). I looked closer now and I see the "LY". So, forget everything I said in my revision.