1964 Locking Gas Cap

[Patrick C.]

Re: 1964 Locking Gas Cap

After all the discussion I went out to my workshop and closely examined both my ‘64 and ‘66 locking caps. I was beginning to doubt my memory.

My ‘64 cap is indeed vented and uses the ignition key. It works great. The cap that came on my ‘66 uses a key labled GAS and is non vented. Looks like the ‘66 may be a cap for a C3 based on Joes detailed discription.

[Joe L.]

Re: 1964 Locking Gas Cap

After all the discussion I went out to my workshop and closely examined both my ‘64 and ‘66 locking caps. I was beginning to doubt my memory.

My ‘64 cap is indeed vented and uses the ignition key. It works great. The cap that came on my ‘66 uses a key labled GAS and is non vented. Looks like the ‘66 may be a cap for a C3 based on Joes detailed discription.

Patrick------


The non-vented cap is a GM #3994340.

Your vented, 1964 cap must have been re-keyed to accept the ignition key somewhere along the way or it's just a coincidence that the ignition key works in the lock..

[Harry S.]

Re: 1964 Locking Gas Cap

Just went to the garage. I have a cap, non-vented, in a box with PN 994179. Gr.3.028

The key is marked GAS. Under GAS is A948 that I assume is the key code.

Any ideas on year and use?

Cheers

[Patrick C.]

Re: 1964 Locking Gas Cap

Patrick------


The non-vented cap is a GM #3994340.

Your vented, 1964 cap must have been re-keyed to accept the ignition key somewhere along the way or it's just a coincidence that the ignition key works in the lock..

My guess it it was rekeyed sometime in its history as the ‘66 GAS key does not work and a dime does not work. It just works too slick...one key for everything on the ‘64. I bet it was done by a professional locksmith back in the day. I will ask the first two owners next time I talk to them.

[Alan D.]

Re: 1964 Locking Gas Cap

Harry,
Did not find pn but it was discontinued on 1-74

[Joe L.]

Re: 1964 Locking Gas Cap

Just went to the garage. I have a cap, non-vented, in a box with PN 994179. Gr.3.028

The key is marked GAS. Under GAS is A948 that I assume is the key code.

Any ideas on year and use?

Cheers

Harry------

This is the 1970-74 non-vented cap. It was first available in 1970 and was discontinued without supersession in November, 1974. Although I can find no record of it, the 3994340 must have co-existed with the 994179 even though it was not cataloged until after the 994179 was discontinued without official supersession.

Does your 994179 have a "textured" surface?

[Harry S.]

Re: 1964 Locking Gas Cap

Harry------

This is the 1970-74 non-vented cap. It was first available in 1970 and was discontinued without supersession in November, 1974. Although I can find no record of it, the 3994340 must have co-existed with the 994179 even though it was not cataloged until after the 994179 was discontinued without official supersession.

Does your 994179 have a "textured" surface?

Nice smooth chrome

Cheers

[Darryl D.]

Re: 1964 Locking Gas Cap

So, is the original non locking gas cap vented or non vented for C2s?

[Joe L.]

Re: 1964 Locking Gas Cap

So, is the original non locking gas cap vented or non vented for C2s?

Darryl-----

All C2's used a VENTED cap.

[Joe L.]

Re: 1964 Locking Gas Cap

Nice smooth chrome

Cheers

Harry------

I have a GM #994179 with a "textured" surface. Here's another:

https://www.ebay.com/itm/ORIGINAL-GM-NOS-1970-1971-1972-1973-1974-Corvette-locking-gas-cap-994179-in-box/382558419000?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20160908105057%26meid%3D844500350bfc48e6a3a72985295147e0%26pid%3D100675%26rk%3D3%26rkt%3D15%26sd%3D223134093308%26itm%3D382558419000&_trksid=p2481888.c100675.m4236&_trkparms=pageci%3Aac4f6ac7-0c0b-11e9-8acf-74dbd1803073%7Cparentrq%3Afe329b011670aa42dd0806d4fff3187a%7Ciid%3A1

[Darryl D.]

Re: 1964 Locking Gas Cap

[QUOTE=Joe Lucia (12484);844705]Darryl-----

All C2's used a VENTED cap.[/QUO

So does that mean that the locking gas cap Without the visible vent hole are also vented?

[Joe L.]

Re: 1964 Locking Gas Cap

[QUOTE=Darryl Dayton (63266);844732]

Darryl-----

All C2's used a VENTED cap.[/QUO

So does that mean that the locking gas cap Without the visible vent hole are also vented?

Darryl------


No, the only vented locking caps for 1963-69 Corvettes are those with the visible hole on the top surface. The non-vented, "no hole" caps can only be used on late 1969's with integral, on-tank pressure-vacuum valve or C2's with a GM replacement gas tank that incorporates the integral pressure-vacuum valve. Otherwise, the "no hole" caps are only applicable to 1970-74 Corvettes.

[Patrick C.]

Re: 1964 Locking Gas Cap

[QUOTE=Joe Lucia (12484);844734]

Darryl------


No, the only vented locking caps for 1963-69 Corvettes are those with the visible hole on the top surface. The non-vented, "no hole" caps can only be used on late 1969's with integral, on-tank pressure-vacuum valve or C2's with a GM replacement gas tank that incorporates the integral pressure-vacuum valve. Otherwise, the "no hole" caps are only applicable to 1970-74 Corvettes.

is there an easy way to tell if you have the later on-tank-vacuum valve vented tank?

[Joe L.]

Re: 1964 Locking Gas Cap

[QUOTE=Patrick Cavanagh (57907);844736]

is there an easy way to tell if you have the later on-tank-vacuum valve vented tank?

Patrick------

Fairly easy. Move the fuel neck seal (boot), looking about 4-5 inches to the left of the filler neck and within the tank-wide recessed area. If you see a round, approximately 1-1/2-2" OD more-or-less flat appearing device on the tank, then you have the integral pressure-vacuum valve. GM instructs that when a SERVICE tank with integral pressure vacuum valve is used, the sealed-type (non-vented) cap should also be used.

Another way to pretty reliably INFER whether the tank has the valve. Look at the tank from under the car. If the tank has the large "roundish" depressions on either end of the tank, the tank probably does not have the pressure-vacuum valve. If the tank has "rectangularish" depressions, the tank probably has the integral pressure-vacuum valve.

[Jeff B.]

Re: 1964 Locking Gas Cap

I bought my 67 in 1978, off a car lot, being sold simply as a used car. Dealer told me the owner said he couldn't afford the gas. It had this locking cap. Back then, DMVs would reveal prior ownership info. I became the fourth (registered) owner of this car. In tracking back and talking with previous owners, the 2nd owner told me he bought the locking from a Chev dealer in 1975, because he thought people were siphoning his gas at night. The gasket was missing when I bought car, but am still using this cap.