Locking Gas Cap

[Mark E.]

Re: Locking Gas Cap

Gas cap 3.jpgGas cap 4.jpgGas cap 5.jpg

Here's the cap that was on my 1970 when I purchased it in 1990.

- It's vented, yet as noted above and verified in the TIM&JC the gas cap in 1970 should be sealed. Is this cap for for 63-69?

- How can you tell if a car should have a sealed or vented cap? I know NA9 equipped cars have a sealed system. But why would a car without a sealed evaporative emissions system have a sealed cap? How are they vented?

- The top is textured rather than smooth. Were both types available over the counter from Chevy?

- And it doesn't come off with a coin.

[Joe L.]

Re: Locking Gas Cap

[ATTACH=CONFIG]61514[/ATTACH][ATTACH=CONFIG]61515[/ATTACH][ATTACH=CONFIG]61516[/ATTACH]

Here's the cap that was on my 1970 when I purchased it in 1990.

- It's vented, yet as noted above and verified in the TIM&JC the gas cap in 1970 should be sealed. Is this cap for for 63-69?

- How can you tell if a car should have a sealed or vented cap? I know NA9 equipped cars have a sealed system. But why would a car without a sealed evaporative emissions system have a sealed cap? How are they vented?

- The top is textured rather than smooth. Were both types available over the counter from Chevy?

- And it doesn't come off with a coin.

Mark-------


What makes you think this locking cap is vented? It's only vented if it has a hole in the TOP surface of the cap. I don't see one on this cap and, in any event, I don't think that any of the caps with the "textured" upper surface were of the vented variety. At least, I've never seen one.

ALL 1970-74 Corvettes used a sealed cap. ALL 1970-74 Corvette fuel tanks were equipped with an integral pressure/vacuum valve. This valve can be seen on the top surface of the tank about 4 or 5 inches to the left of the filler opening (boot must be pulled back to see it). Actually, late 1969 Corvettes had the same valve but they were originally equipped with a vented cap.

For many years, SERVICE fuel tanks for all 1963-69 Corvettes were equipped with the pressure vacuum valve and GM instructed that when these tanks were used on a 63-69 Corvette, the sealed cap should also be used.

Both the smooth and "textured" caps were sold by GM. However, as I mentioned, I've never seen the textured used for a vented cap. The sealed caps came both smooth and textured. Most, if not all, non-GM-sourced caps were of the textured variety. However, these caps usually have a non Briggs and Stratton key which has a different head shape than the one you pictured.

[Mark E.]

Re: Locking Gas Cap

What makes you think this locking cap is vented? It's only vented if it has a hole in the TOP surface of the cap.

Thanks for your reply Joe; very helpful. It didn't show up in the earlier photos, but there is a small hole (3 o'clock position in the photo below). I assume that's the vent? If yes, I'll check to see if my 1970 has the pressure vacuum valve as you mentioned it should.

If it does have this valve, then this car should have a sealed cap, right?


Gas cap 6.jpg

[Richard W.]

Re: Locking Gas Cap

I have the identical cap on my '63 and have never had a proplem. It has no gasket, but it appears to a somewhat loose fit that compensates for the venting issue. It is interesting that it also has a venting hole on the bottom side but not the top. My key just says "GAS".

[Joe L.]

Re: Locking Gas Cap

Thanks for your reply Joe; very helpful. It didn't show up in the earlier photos, but there is a small hole (3 o'clock position in the photo below). I assume that's the vent? If yes, I'll check to see if my 1970 has the pressure vacuum valve as you mentioned it should.

If it does have this valve, then this car should have a sealed cap, right?


[ATTACH=CONFIG]61517[/ATTACH]

Mark------


Yes, that's the vent hole. This is the first one I think I've ever seen on one of the "textured" caps. This cap is for 1963-69. However, it can be used on later models without creating any real problem.

[Mark E.]

Re: Locking Gas Cap

Thanks Joe.