Which trucks had vent lines on the gas tank? - Page 2 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**Ironangel** · 01-09-2013, 06:02 AM

My 72 C-10 is "vented"

Sir Psycho C10 · 01-09-2013, 08:05 AM

My 72 C-10 is non-vented since it was set up with California Emissions.

Emissions stuff is all gone today and all vents are being capped this week. They were all dry rotted anyway. So I need a vented cap quick!!! Seems they are hard to come by.

If anyone knows what brand & p/n will fit, please let me know. Still has original tank.

yuccales · 01-09-2013, 10:02 AM

Quote:

Originally Posted by Sir Psycho C10

My 72 C-10 is non-vented since it was set up with California Emissions.

Emissions stuff is all gone today and all vents are being capped this week. They were all dry rotted anyway. So I need a vented cap quick!!! Seems they are hard to come by.

If anyone knows what brand & p/n will fit, please let me know. Still has original tank.

NAPA has them both, vented & non-vented.

Z10 · 01-09-2013, 06:12 PM

So, if 72's came with non-vented caps (other than California) where 73 and up caps non-vented and will they fit?

Sir Psycho C10 · 01-09-2013, 06:19 PM

Not sure,

I found a vented gas cap that fits great. Autozone P/N 6742. Now I need to find out if it vents in and out to keep the tank stable.

Cali trucks should have non-vented gas caps off the assembly line.

1972SUPERSB · 01-09-2013, 06:21 PM

Quote:

Originally Posted by Sir Psycho C10

Not sure,

I found a vented gas cap that fits great. Autozone P/N 6742. Now I need to find out if it vents in and out to keep the tank stable.

Cali trucks should have non-vented gas caps off the assembly line.

I think I tried this cap and it seemed to fit a little loose like you can move it side to side? I still haven't found a gas cap that fits right.
Posted via Mobile Device

GASoline71 · 01-09-2013, 06:26 PM

I removed all the vent lines and capped them off in my 1972 GMC 1500. I then purchased a "vented" gas cap for a 1972 and it works just fine.

Gary

Sir Psycho C10 · 01-09-2013, 06:33 PM

I just got off the phone with CST - manufacturer of the gas cap (Autozone) 6742. He said it is vented both ways.

-.5 PSI will take from outside air.
3.0 PSI will burb from tank.

I was so temped to just drill a small 1/16" hole in mine and be done. Figured I would keep searching. Got what I need now.

For $6.99 it may be worth a shot....they'll take it back if it doens't fit.

Sir Psycho C10 · 01-09-2013, 06:34 PM

1972SuperSB -

You may have some wear on your filler neck. May be able to install another rubber gasket to get above the wear point.

Mine fit so tight I could barely grip the cap.

54blackhornet · 01-09-2013, 07:24 PM

I just overhauled the entire fuel system on a 71 GMC, 1st thing the factory service manual explains the EEC system on 71' 72 and some 70's . If tank has small hose connection on pass side you should use a non vented cap, if the EEC is intact and function able. The system captures fuel vapors and redirects it back to carb to reburn. Early tanks vented caps, both available at NAPA.
Posted via Mobile Device

1972SUPERSB · 01-09-2013, 07:48 PM

Quote:

Originally Posted by Sir Psycho C10

1972SuperSB -

You may have some wear on your filler neck. May be able to install another rubber gasket to get above the wear point.

Mine fit so tight I could barely grip the cap.

You may be right I'm gonna check it out tonight.
Posted via Mobile Device

01-09-2013, 06:02 AM	#26
Ironangel Senior Member Join Date: Feb 2010 Location: Falls City, Nebraska "100 Miles From Nowhere" Posts: 2,219	Re: Which trucks had vent lines on the gas tank? My 72 C-10 is "vented" __________________ Michael of the clan Hill, "Two Seventy Two's" 71 1-ton Dually 350 4-Speed 71 C/50 Grain Truck, 350 Split-Axle 4-Speed 02 3/4 ton Express 14 Indian Chief Vintage 1952 Ford 8N, "Only Ford Allowed On The Property" "Be American, Buy American"

01-09-2013, 08:05 AM	#27
Sir Psycho C10 Registered User Join Date: May 2012 Location: Atlanta, GA Posts: 34	Re: Which trucks had vent lines on the gas tank? My 72 C-10 is non-vented since it was set up with California Emissions. Emissions stuff is all gone today and all vents are being capped this week. They were all dry rotted anyway. So I need a vented cap quick!!! Seems they are hard to come by. If anyone knows what brand & p/n will fit, please let me know. Still has original tank. __________________ 72 C10 Deluxe Medium Blue/White 350/350

01-09-2013, 06:12 PM	#29
Z10 Registered User Join Date: Aug 2012 Location: Midland, TX Posts: 1,267	Re: Which trucks had vent lines on the gas tank? So, if 72's came with non-vented caps (other than California) where 73 and up caps non-vented and will they fit? __________________ 1969 RS/SS Z10 Camaro Pace coupe 1972 GMC Short Step buildhttp://67-72chevytrucks.com/vboard/s...=1#post6356218 1979 Mazda RX7 1979 Pontiac Trans Am WS6 & 1979 Pontiac Trans Am 10th Anniversary 1999 Honda Valkyrie 2006 Corvette Z06 2010 BMW 650i

01-09-2013, 06:19 PM	#30
Sir Psycho C10 Registered User Join Date: May 2012 Location: Atlanta, GA Posts: 34	Re: Which trucks had vent lines on the gas tank? Not sure, I found a vented gas cap that fits great. Autozone P/N 6742. Now I need to find out if it vents in and out to keep the tank stable. Cali trucks should have non-vented gas caps off the assembly line. __________________ 72 C10 Deluxe Medium Blue/White 350/350

01-09-2013, 06:33 PM	#33
Sir Psycho C10 Registered User Join Date: May 2012 Location: Atlanta, GA Posts: 34	Re: Which trucks had vent lines on the gas tank? I just got off the phone with CST - manufacturer of the gas cap (Autozone) 6742. He said it is vented both ways. -.5 PSI will take from outside air. 3.0 PSI will burb from tank. I was so temped to just drill a small 1/16" hole in mine and be done. Figured I would keep searching. Got what I need now. For $6.99 it may be worth a shot....they'll take it back if it doens't fit. __________________ 72 C10 Deluxe Medium Blue/White 350/350

01-09-2013, 06:34 PM	#34
Sir Psycho C10 Registered User Join Date: May 2012 Location: Atlanta, GA Posts: 34	Re: Which trucks had vent lines on the gas tank? 1972SuperSB - You may have some wear on your filler neck. May be able to install another rubber gasket to get above the wear point. Mine fit so tight I could barely grip the cap. __________________ 72 C10 Deluxe Medium Blue/White 350/350

01-09-2013, 07:24 PM	#35
54blackhornet Registered User Join Date: Jul 2008 Location: Eastern Oregon Posts: 2,406	Re: Which trucks had vent lines on the gas tank? I just overhauled the entire fuel system on a 71 GMC, 1st thing the factory service manual explains the EEC system on 71' 72 and some 70's . If tank has small hose connection on pass side you should use a non vented cap, if the EEC is intact and function able. The system captures fuel vapors and redirects it back to carb to reburn. Early tanks vented caps, both available at NAPA. Posted via Mobile Device __________________ 71 C-20 07 Magnum RT AWD



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