Author Topic: Gas cap for '69 Camaro GM part number #3931449  (Read 2386 times)

Fred Mertz

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Gas cap for '69 Camaro GM part number #3931449
« on: January 25, 2015, 04:48:06 AM »
I suspect this cap is no longer correct for a '69.  A '69 gas cap should be "vented".   The caps I've been getting are in AC Delco boxes and use GM#3931449.  The last 3 caps I have gotten are not actually vented causing the needle and seat to seep. This causes a gas smell to build up the my garage after driving my car.  I have to remove the gas cap to relieve the back pressure.

These caps are marked "Vented" but are in fact "Non Vented caps"   The non-vented caps appear to be of the same construction.

Where can I get a correct gas cap?  My local dealerships don't stock the caps any longer but can order them, but they are not correct.

Ideas please.  I have been able to find good caps in the past but not lately.  Dave

69Z28-RS

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Re: Gas cap for '69 Camaro GM part number #3931449
« Reply #1 on: January 25, 2015, 05:08:52 AM »

Aren't the vented caps simply made with a tiny hole in them, and use a cardboard 'seal' inside (or semi seal)??  Maybe whomever mfg'ed that 'vented' cap didn't vent it correctly?
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rich69rs

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Re: Gas cap for '69 Camaro GM part number #3931449
« Reply #2 on: January 25, 2015, 06:24:24 AM »
Not venting the gas tank properly could cause the tank to collapse (or at least deform) as the volume of gas inside decreases with driving and you begin to pull a partial vacuum inside the tank.  Had this happen to me once before in a VW Rabbitt back in the day.
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m22mike

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Re: Gas cap for '69 Camaro GM part number #3931449
« Reply #3 on: February 09, 2015, 03:04:34 AM »
I suspect this cap is no longer correct for a '69.  A '69 gas cap should be "vented".   The caps I've been getting are in AC Delco boxes and use GM#3931449.  The last 3 caps I have gotten are not actually vented causing the needle and seat to seep. This causes a gas smell to build up the my garage after driving my car.  I have to remove the gas cap to relieve the back pressure.

These caps are marked "Vented" but are in fact "Non Vented caps"   The non-vented caps appear to be of the same construction.

Where can I get a correct gas cap?  My local dealerships don't stock the caps any longer but can order them, but they are not correct.

Ideas please.  I have been able to find good caps in the past but not lately.  Dave
r
Read this thread, your cap should not be vented directly to atmosphere
http://www.camaros.org/forum/index.php?topic=8756.0


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L78 steve

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Re: Gas cap for '69 Camaro GM part number #3931449
« Reply #4 on: February 10, 2015, 06:27:33 PM »
Your cap is vented. Vented in one direction, In. The tank should not build enough pressure to pop off your carb needle and seat. You need to check other possibility's for the gas smell.
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