Fuel Tank Vent Tube - Question

Did my search on vented gas tanks, learned allot, but have one question.

I mounted my gas filler tube in the trunk, it sticks up about 1 foot, and I am going to run a vent line from the top of the filler tube near the non venting gas cap.
My question is, does the vent tube have to be run or terminated higher than the gas tank, or can I run it through a hole in the trunk and let it vent down below, at about the same level as the tank?

Thanks, Mike

 

Since your filler neck is above the tank, and you will never fill gas near the top of that neck it should be OK to run below tank.
I installed a tankthat had next to no neck and ran the vent tube slightly below the top of tank. It was fine till I filled it with gas and then when acclerating or going up a hill gas would come out of vent tube.Moved end of tube a 2-3 inches above top of tank and has been fine since.

 

I am using a non vented cap on my car and I ran a threaded fuel line into the filler and up and past the gas cap inside the fender, with a little trap at the top.
You don't want gas to be able to come out if the tank is full.

 

You could also get a charcol canister at the bone yard and run it through that if you didn't want to put another hole in the trunk.

 

I shortened the filler neck on my '54 and ran it straight up into the trunk. The cap sits about 3" above the trunk floor now. I made a small bung for the side of the filler neck, then ran hard line down and forward along the frame rail. The end of the line is about even with the drivers side axle tube. I used a differential vent on the end of the line to keep any garbage out. The line is long enough and high enough that I shouldn't have to worry about fuel coming out.

 

So if it is lower it still vents, the main concern with a low one is fuel comming out ..... right?

 

It'd be best if the vent is above the fuel level. That's why I ran mine along the frame to the high point, just even with the rear wheels.

 

I made a 180 degree loop in a 3/16 brake line, and ran it through the filler neck just under the filler cap. There is a rubber grommet where the small tube goes through the neck, then the tube goes across the tank and through a clamp, then there is small hose that vents it just inside the frame away from the exhaust. In the garage, it smells of gas. I may try a carbon can some time.