Gas tank cap - Team Camaro Tech
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post #1 of 8 (permalink) Old Jun 4th, 15, 10:09 PM Thread Starter
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Gas tank cap

The gas tank cap is under a lot of pressure whenever I remove it to fill up the tank. Is this normal? This is on an original 1969 SS with 396 engine; car runs fine.
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post #2 of 8 (permalink) Old Jun 4th, 15, 10:23 PM
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Re: Gas tank cap

Normal

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post #3 of 8 (permalink) Old Jun 5th, 15, 06:39 AM
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Re: Gas tank cap

Agree very normal.


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post #4 of 8 (permalink) Old Jun 5th, 15, 07:01 AM
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Re: Gas tank cap

Does the Stock Cap Vent Both ways ?
Would the Summer Heat build enough pressure to push Fuel and Vacuum when Cools down.
I do realize these Systems have lasted 40+ years too, just Thinking - Hmm
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post #5 of 8 (permalink) Old Jun 5th, 15, 07:34 AM
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Re: Gas tank cap

C'mon Timmy! Now you're just showing off the rotisery and sweet ride on it!! haha!! Sorry, I'm just gealous!! Nice tank!!
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post #6 of 8 (permalink) Old Jun 5th, 15, 07:39 AM
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Re: Gas tank cap

Stock cap vents in only. And no problem in the summer.
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post #7 of 8 (permalink) Old Jun 5th, 15, 08:45 AM
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Re: Gas tank cap

Sealed systems were emissions controls added in the early 70's and in place by 74 for GM if I remember right. The pre sealed system caps used in 67,68 69 Camaros allowed air in the tank so the pressure of fuel being pulled out by the engine wouldn't cause a vacuum. As said the temperature can greatly effect tank pressure. If the beads in the cap that form the vent are damaged you can get a partial collapsed tank if there is a sudden temp change such as adding cold fuel to a hot empty tank. Usually these dents pop out again once the fuel reaches road temps. But still fund and scary to watch.


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post #8 of 8 (permalink) Old Jun 6th, 15, 04:02 PM
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Re: Gas tank cap

Back went I was questioning the tank pressure in my 69, I called Stant to discuss, they said the cap will release pressure after a certain psi, can't recall what psi they said though. I confirmed it at the time using a rubber tipped blow nozzle with regulator set to the psi they said, and it did indeed blow back thru.
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