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Fuel tank vent

fordsbyjay

Active Member
I was wondering how people vent their fuel tanks. Mine sits really high compared to the body so there is a 90* in the top of the tank and then it just wraps around. Problem is if I fill it up as the fuel expands it overflows out the line so I can only put in approx. 3/4 of a tank. I need some type of check valve in there.
 
I had the same problem when I first put the car together.

I used a roll-over vent valve from Speedway in the top of the tank and routed a loop of stainless tubing into a cavity behind the seat. That gave me a high point in the loop that was higher than the tank. I connected that to a hose with a screen under the car.

Mike
 
I was wondering how people vent their fuel tanks. Mine sits really high compared to the body so there is a 90* in the top of the tank and then it just wraps around. Problem is if I fill it up as the fuel expands it overflows out the line so I can only put in approx. 3/4 of a tank. I need some type of check valve in there.

If I did it right. these photos show how I did mine. The tank vent has a roll-over valve in it.


http://www.tbucketee...-gas-tank-vent/
 
If I did it right. these photos show how I did mine. The tank vent has a roll-over valve in it.


http://www.tbucketee...-gas-tank-vent/

I like your setup but I don't have that kind of real estate in my car. I will try a check valve from speedway but I still don't have any room to get higher than the tank.

speedway check valve
458400_L.jpg


My tank with regular barbed fitting.
IMG00033.jpg
 
Depending on the tank's fill tube, some have a vented cap. Good question though, now I'll have to see what I have on my tank that hasn't been installed yet.
 
I was wondering how people vent their fuel tanks. Mine sits really high compared to the body so there is a 90* in the top of the tank and then it just wraps around. Problem is if I fill it up as the fuel expands it overflows out the line so I can only put in approx. 3/4 of a tank. I need some type of check valve in there.

heres one from Earls. Its 2 way. Allows vent when fuel off gases and air in when engine running. Still needs the pipe to be higher than the tank at some point to stop the off gas pushing fuel out.
vent.JPG

Gerry
 
Fordsbyjay: I think your cap already has a vent in it.??

Question for you guys.
With a vent in the cap does nt that mean all the vapor is going to come out where people may be looking around the T, possibly with a cig in their hands. The reason car makers put the vent tube to the underside and bottom of the car is to make sure its diluted by the time it get to the open air.
Is that right?
Gerry
 
The vented cap has a one way valve. Lets air in, seals fumes in tank. If you've got enough gasoline fumes around your car that can form a combustable mixture with the air, you've got a real big problem and should fix it before you take that car into public.
 
The vented cap has a one way valve. Lets air in, seals fumes in tank. If you've got enough gasoline fumes around your car that can form a combustable mixture with the air, you've got a real big problem and should fix it before you take that car into public.

OK so what happens to the pressure build up on a hot day with no vent to atmosphere?
Experience tells me that a little gasoline vapor and air loves to ignite. Could be wrong here just asking. Ever see F1 pit fires?
Gerry
 
Hey guys, why don't you PM Ron over at his business...he builds tanks and can give ya the lowdown on venting. Putz, BlownT, Mango and others can also help ya out.

I've been out of the shop here lately, on the road....going back out the next few days....
 
OK so what happens to the pressure build up on a hot day with no vent to atmosphere?
Experience tells me that a little gasoline vapor and air loves to ignite. Could be wrong here just asking. Ever see F1 pit fires?
Gerry

Yea Gerry, on hotdays the fuel tank can shove fuel up into your carb, past your fuel pump and a shutoff valve. I've even seen them blow off the fuel lines being held on by those little 'cheesy' snapring-type hose clamps.
 
Here's my vent: an adapter, 1/4NPT-#6AN, with a cap. Stuff the cap and adapter with steel wool, seal the bottom with a plug of epoxy. Drill a tiny hole in the epoxy. File or grind a small groove in the adapter AN mating surface for the air to get in. Fuel would have to get thru the little hole, then thru the steel wool. I've used this design for years. Make sure the bottom of the adapter doesn't reach into the fuel, or fuel would be squeezed up thru it as the air in the tank warms and expands.
 

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