How does fuel tank vent?

Oldchevyguy

Well-Known Member
Hi there! Just wondering if I should save my charcoal vapor canister for the SS doner? Or do you use a vented cap? No mention in any of the videos. Please explain.
 

DCMoney

Goblin Guru
Don't need it.

Vent is on top of the tank, there's a tee that comes with the kit. Vents to atmosphere, have the hose going in front of the tank out of the ground.
20191013_095451.jpg
 

Ross

Goblin Guru
I thought that hose was suppose to go up to the seat belt bar, then down to ground level. If the car is upside down, the gas won't drain out.
 

DCMoney

Goblin Guru
I thought that hose was suppose to go up to the seat belt bar, then down to ground level. If the car is upside down, the gas won't drain out.
Good call.

 

Oldchevyguy

Well-Known Member
I thought that hose was suppose to go up to the seat belt bar, then down to ground level. If the car is upside down, the gas won't drain out.
That might work better than a rollover valve. I have factory 5 GTM with two corvette tanks vented with rollover valves. I park it in a hot trailer, and there is a strong smell of gas. Maybe this setup would keep that from happening?
 

TheNuker

Goblin Guru
Please explain how you did this.
I clamped a hose from the metal hard line coming from the gas nozzle to the brass barb that you screw into the aluminum tank. I sealed that with a fuel safe sealer forgot the name. Kinda 2 fold I did not want any moisture in my E85 as that stuff sucks up water, and If I ever flipped I wanted no chance of that leaking out and turning me into a marshmallow over the fire :D

Nuker-
 

Oldchevyguy

Well-Known Member
There has to have some way for air to replace fuel, or you will burn out your fuel pump. The stock CV k setup draws air threw the evap canister. I have heard of other people who did what you did having problems.
 

Lonny

Administrator
Staff member
E85 must be different than gas, when we built Adam's first car we installed a supercharger kit from ZZP. It had an unvented gas tank. It would swell the tank after a few minutes of driving and it seemed like it affected the fuel pressure.

The fuel pressure regulator is in the pump, so I guess if you have five pounds of pressure in the tank the fuel pressure will have to increase by five pounds to overcome the regulator.

We vent the tank in two places, we had to do this to help keep gas flowing into the tank smoothly during fill-ups. They tee into one tube that is ran across the tank to the middle of the car and then out slightly past the bottom of the car. In the case of a roll over this places the only tank vent above the tank.

 

Briann1177

Goblin Guru
The vapor pressure for E85 is quite a bit less than pure gasoline which explains why your tank swelled with regular gas.
 

Rabid Sloth Racing

Active Member
With the vent tube exiting below the middle of the tank, wouldn't it still be a leak risk if the car rolled onto the passenger side? Shouldn't it come out of the top of the tank, go slightly to the passenger side and behind the tank, then slightly past the drivers side before exiting infront of and below the tank to create gravity traps in any position the car could end up in?
 

Ark :D

Goblin Guru
I presume the hoses used for the venting do not need to be fuel-rated?.... considering if they actually have fuel in them, I'm probably a corpse? lol
 
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