Fuel cap

[reborn55]

Have an aftermarket later model fuel inlet on coupe. Has what appears to be original gas tank(no vent) and screw in type gas cap. Cap has a little hole drilled in it for venting purposes. Sometimes fuel will slosh and gas smell can get bad--fumes will get bad on hot days. Do they make a vented screw in type cap that works the same way as the one I have with out releasing the fuel odor. Think mid 80's carbureted GM caps might work.. Don't want to get wrong cap and suck the tank flat. Thanks in advance

[enjenjo]

Not that I know of. GM did not use a vented cap after the late 60s.

[wayne petty]

this link will download a 2004 stant cap and thermostat catalog section..

i tried to click to open it.. .. try to click to download file...


http://www.stant.com/catalogs/filedisplay.cfm?file=Stant_Caps_Stats_Alpha.pdf&thisPath=stant%5Ccatalogs

[reborn55]

I have seen many ads for vented gas caps for 82-92 GM products--are these really vented or just pressure relief

[enjenjo]

Is there any place to install a vent on the tank?

the pressure releif caps are not vented either.

[wayne petty]

stant screw in non locking caps...  right from page 27 of the link i posted.. if your cap is 1 49/64 thread size....  which should be a later model GM..


10819
PRE-VENT®
PRESSURE VACUUM TYPE
FOR EMISSION CONTROL


10825
VACUUM ONLY

http://contentinfo.autozone.com/znetcs/product-info/en/US/cst/6825/image/4/


10826
NON-VENTED

10827
PRESSURE RELIEF

i would really think...  that figuring out the fuel tank venting system... installing a carbon canister...  with a vacuum hose to the intake manifold vacuum.. and one to ported vacuum to control the purge flow only when the engine is above idle... a bunch of different ways to hook up a carbon canister... but there has been success with them reducing the amount of fuel vapors in a garage...   people have also emptied the fuel bowls by shutting off the fuel flow...   letting the engine run out of fuel....  i wonder .. if you do this with a 4150/4160 version.. i would imagine the secondary fuel bowl stays full...  it would work on an AFB/avs style of carb...

there was during the late 70's to the early 80s...   GM air filters.. with a secondary filter looking sort of thing... but it did not contact the top cover of the air filter... it was filled with carbon granules and absorbed fuel vapors.. then allowed them to be burned when the engine started..

[reborn55]

Is there any place to install a vent on the tank?

the pressure releif caps are not vented either.

Has original tank I am pretty sure and haven't dropped it.  Guess next project after this weekend's road trip

[enjenjo]

If you can remove the fuel inlet pipe, do so, and weld a fitting in the side for a vent below the cap. Then run a hose from that in a U up into the body so it doesn't spill when full. You want the end of the hose outside the body.

[reborn55]

As far as a pipe--all that is there is a fuel hose from the tank to the filler neck that is molded into the body

[wayne petty]

like this...

http://www.trifive.com/garage/55%20Chevy%20Assembly%20Manual/8-2.gif


a few more...

http://www.trifive.com/garage/55%20Chevy%20Assembly%20Manual/8-1.gif

this probably won't help much... but..

http://www.trifive.com/garage/55%20Chevy%20Assembly%20Manual/12-27.gif

[enjenjo]

As far as a pipe--all that is there is a fuel hose from the tank to the filler neck that is molded into the body

Then you can attach a vent to the hose. I can think of several ways of doing it.