Advice wanted on venting my gas tank - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**Yukon Jack** · 02-02-2005, 12:58 PM

Here is the gas tank on my 69 K20.

Here is a threaded fitting on the top passenger side of the tank where I can attach a line to vent the tank.

Would like suggestions on how I should vent the tank. If I just put a copper line running down will that cause an evaporation problem? Should I put some sort of breather on the line? A friend suggested drilling a hole in the headache rack support and put the line in there and have it pointing up.

Let's here some suggestions please.

86SILVERADO · 02-02-2005, 01:20 PM

Why not just do it with a vented cap? Are you unable to get one for the fuel cell? If you have to use the vent I would pull a charcoal canister from some old rig and plumb it into that and your carb emissions era style. Just make sure you use all the proper hoses and there should be a check valve in there in case of a backfire.

OLDCHEV4X4 · 02-02-2005, 01:21 PM

Run a line lower than the bottom of the tank and then put a check valve on it. I think Jegs has them. Then put a breather on the end of that. If you ever roll it over, gas woulnt spill out.
Randy

**tnblazerk5** · 02-02-2005, 01:30 PM

i dont think i would want it in the headache rack !! if the vapors are in the headache rack and a spark near any hole in the rack and that could be a big boom !!!!!!! really big pipe bomb . and if you put it down sumwhere and gas does get in it,it will empty the tank like a sighferring(<sp)hose . if it was mine i would run a hose up to the top of the rack,out of harms way, and put a filter on it to keep crap out of the line

but thats just my 2cents worth

**Yukon Jack** · 02-02-2005, 01:45 PM

I don't think it could siphon out unless the truck was in an off camber position - there is not a line going inside the tank that would allow it to siphon out.

**tnblazerk5** · 02-02-2005, 01:48 PM

ok i didnt know if there was or not

Mudder · 02-02-2005, 02:07 PM

Wheres your exhaust gonna run to? I would maybe run it down with your line and through the bed and then to the back away from the exhaust. Heres what I did with mine and I stand right there while putting gas in and I never smell it.

**Yukon Jack** · 02-02-2005, 04:00 PM

The line going to the carb is on the driver side so won't be convenient to put it in the same location.

stllookn · 02-02-2005, 06:04 PM

Hey, Why not just vent it into the cab like GM did...keep it stock. Those fumes are heavier than air so they stay in the tank...that is why there was never a risk of smokers in the cab lighting the thing off...unless you turn the truck upside down...LOL! Probably not so funny if it was my truck...or yours! Vent it anywhere up and you will be fine. Put a charcoal canister on it or run it into the air cleaner if you really want to be environmentally responsible.

02-02-2005, 12:58 PM	#1
Yukon Jack Post Whore Join Date: Feb 2000 Location: Rose Hill, KS, USA Posts: 12,684	Advice wanted on venting my gas tank Here is the gas tank on my 69 K20. Here is a threaded fitting on the top passenger side of the tank where I can attach a line to vent the tank. Would like suggestions on how I should vent the tank. If I just put a copper line running down will that cause an evaporation problem? Should I put some sort of breather on the line? A friend suggested drilling a hole in the headache rack support and put the line in there and have it pointing up. Let's here some suggestions please. __________________ 1970 Blazer with a 400 sbc and 4" lift 1980 Pontiac Trans Am, 455 Oldsmobile 2012 Kawasaki Concours 14

02-02-2005, 01:20 PM	#2
86SILVERADO Registered User Join Date: Dec 2002 Location: Hills of Western Mass Posts: 626	Why not just do it with a vented cap? Are you unable to get one for the fuel cell? If you have to use the vent I would pull a charcoal canister from some old rig and plumb it into that and your carb emissions era style. Just make sure you use all the proper hoses and there should be a check valve in there in case of a backfire. __________________ 86 Silverado C10 back to 305 power! 67 C30 Dually Dump, with 350 transplant, Rockhauler 05 Duramax 3500 "If at first you don't succeed, try a bigger hammer" Member of the 1-Ton club!

02-02-2005, 01:21 PM	#3
OLDCHEV4X4 Registered User Join Date: Apr 2000 Location: Chester County PA, USA Posts: 1,228	Run a line lower than the bottom of the tank and then put a check valve on it. I think Jegs has them. Then put a breather on the end of that. If you ever roll it over, gas woulnt spill out. Randy __________________ 72 k/10 short wideside 72 k/5 Blazer 72 K/5 Blazer - obstacle course racer 72 custom/10 8' bed 70 K/5 Blazer 67 C-30 GMC Flat bed 86 GMC K2500 Plow Truck 85 GMC K3500 84 M1008 85 M1008 77 G30 Motor Home 72 Sears 12hp Tractor Glenmoore, Pennsylvania

02-02-2005, 01:45 PM	#5
Yukon Jack Post Whore Join Date: Feb 2000 Location: Rose Hill, KS, USA Posts: 12,684	I don't think it could siphon out unless the truck was in an off camber position - there is not a line going inside the tank that would allow it to siphon out. __________________ 1970 Blazer with a 400 sbc and 4" lift 1980 Pontiac Trans Am, 455 Oldsmobile 2012 Kawasaki Concours 14

02-02-2005, 02:07 PM	#7
Mudder Registered User Join Date: Feb 2001 Location: East Central, MO Posts: 11,336	Wheres your exhaust gonna run to? I would maybe run it down with your line and through the bed and then to the back away from the exhaust. Heres what I did with mine and I stand right there while putting gas in and I never smell it. Attached Images

02-02-2005, 01:30 PM	#4
tnblazerk5 User #12137 Join Date: Apr 2004 Location: kingsport,upper east tenn Posts: 11,598	i dont think i would want it in the headache rack !! if the vapors are in the headache rack and a spark near any hole in the rack and that could be a big boom !!!!!!! really big pipe bomb . and if you put it down sumwhere and gas does get in it,it will empty the tank like a sighferring(<sp)hose . if it was mine i would run a hose up to the top of the rack,out of harms way, and put a filter on it to keep crap out of the line but thats just my 2cents worth

02-02-2005, 01:48 PM	#6
tnblazerk5 User #12137 Join Date: Apr 2004 Location: kingsport,upper east tenn Posts: 11,598	ok i didnt know if there was or not

02-02-2005, 04:00 PM	#8
Yukon Jack Post Whore Join Date: Feb 2000 Location: Rose Hill, KS, USA Posts: 12,684	The line going to the carb is on the driver side so won't be convenient to put it in the same location. __________________ 1970 Blazer with a 400 sbc and 4" lift 1980 Pontiac Trans Am, 455 Oldsmobile 2012 Kawasaki Concours 14

02-02-2005, 06:04 PM	#9
stllookn Saving 1 truck at a time! Join Date: Aug 2001 Location: Kent, WA Posts: 6,465	Hey, Why not just vent it into the cab like GM did...keep it stock. Those fumes are heavier than air so they stay in the tank...that is why there was never a risk of smokers in the cab lighting the thing off...unless you turn the truck upside down...LOL! Probably not so funny if it was my truck...or yours! Vent it anywhere up and you will be fine. Put a charcoal canister on it or run it into the air cleaner if you really want to be environmentally responsible. __________________ '68 C20 Longhorn 50th Anniversary 400/TH400 '68 C20 Longhorn 50th Anniversary 468/TH400w/buckets '72 C20 Halfhorn (Longhorn w/o cab and front clip) '69 Flxible Cruiser (look up ugly in the dictionary)



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