New Tank - Venting Question

[Mheiron]

I’m trying to understand the “right way” to run the vent line for a new Aeromotive Stealth fuel tank. The car is a 69 Charger with a Hellcrate up front.

The vent originally ran back up to the filler neck and I believe the cap itself is vented.

My question, is the “vented gas cap” adequate for this high performance application?

If l avoid the filler neck option l was considering alternate vent locations but:

A new vent line and rollover valve is supposed to be located above the rest of the fuel system (including the filler neck). It is also recommended to vent outside the car. I don’t think such a location exists on a 69 Charger with cap located at the top of the rear fender.

This Stealth tank came with 4 vent tubes so they must think it takes a lot of venting.

Thanks for any thoughts or previous experience!

 

[diesel_lv]

I have an Aeromotive Stealth tank in my '67. I use a vented cap and so far have had no issues w my 496" engine. It has a 340lph pump in it running at 100% duty cycle.

 

[diesel_lv]

The fuel pump and bladder on my Stealth tank was mounted at the top front of tank. Once the tank was down to almost 1/2 left, 11 gallons, it would starve for fuel on long upgrades of even 2%. I had to pull the tank, buy Aeromotive's "Bladder Baffles" and "Siphon Pump", and install. Once that was done, no more starving in grades. The tank came pre-assembled, go to their website and look at the bladders, then look at the baffles and Siphon pump before you finish your install.

 

[TN Mopar]

I used the Tanks inc EFI tank in my 66 Charger
It has 2 added vents besides the factory vent & vented cap
It was a bit of a pain to get it plumbed correctly but
Well worth it
It fills very fast and I have no worries about the tank pressure
I am glad we took the time and trouble to vent it correctly

 

[Mheiron]

So it turns out, the stock cap is not vented at all. It’s solid and spring loaded. A tank vacuum will seal it tighter.

I have no idea how a stock tank gets vented.

A new tank for EFI will definitely need a new vent and pressure relief system.

After looking at this some more,

I’ve decided to run 2 x 3/8” lines from the tank.
The first will be for air inlet and will have a check valve near the tank. I intend to run it up behind the sail panel to a point higher than the fill neck and terminate it with a small air filter. This line will keep the tank vented during hard acceleration. The check will also serve as a rollover valve as nothin will be allowed up the vent from the tank by the check.

The second line will be for pressure relief and will be checked opposite of the first. Only tank pressure buildup is allowed down this line. It will follow the 1st up the sail panel to again be higher than the filler neck but then it will continue back down to below the car (to keep out fumes). This line will equipped with a T at the top and a check valve to break any siphon that might get started. The exit will be lower than the tank so in the event of a rollover the bleed off tube will be above tank level which should keep the gas contained anyway.

Haven’t started the pluming yet but thought I’d share the plan as I can’t find much specific detail on this topic.

Thanks for your thought or further comments!

 

[TN Mopar]

The Tanks inc tank came with a check ball and a y
The Tank had a vent nipple added behind the pump shelf and the Pump itself has a vent
These were y's together and mounted inside the filler door
I used 6an line (3/8) for the vent lines and the return line
8an for the supply

 

[1STMP]

Did the same as TN Mopar. Used a roll over
check valve, bug screen, charcoal
master cylinder booster line filter, sealed
cap. Inexpensive and easy.
No fumes in the garage.

 

[Mheiron]

So I think I have a plan….
The problem I think is caused by the tank filler being located on top of the fender. The vents (air inlet and expansion vent) need to be higher than the filler. The only place higher than the fender top is up inside the sail panel / rear roof support.
So here’s the immediate problem, I need to cross the frame rail with the vent lines.
I dont want to go under as that would created a line trap.
Unless I think of something else I’ll need to drill 2 3/8” holes in the frame rail.
I’m open to a better idea if anyone has one! The tank vents are shown in top of the photo.
Thanks in advance for any further ideas……

 

[Aron]

Hey TN, I have a question about this that I think is similar and maybe you - or the other folks on this thread can help: I have a Tanks Inc. new tank for my '68 Charger. It has three sending units on top of the in-tank pump for my EFI system that will feed a 6.1 liter Gen 3 Hemi.

I will run a supply line, a return line and then there is the nipple / outlet for the vent line.

My question is this: For the vent line, I plan to run it to a charcoal filter and then...where? Do I run this all the way up to and into the intake manifold? Or can I just vent it somewhere along the frame rail? Some of the replies on this thread make me think it has to be higher than the 'race fill' gas cap on the fender...or am I reading this all wrong?

Thanks for the help!
-Aron

The Tanks inc tank came with a check ball and a y
The Tank had a vent nipple added behind the pump shelf and the Pump itself has a vent
These were y's together and mounted inside the filler door
I used 6an line (3/8) for the vent lines and the return line
8an for the supply

View attachment 1241765

The Tanks inc tank came with a check ball and a y
The Tank had a vent nipple added behind the pump shelf and the Pump itself has a vent
These were y's together and mounted inside the filler door
I used 6an line (3/8) for the vent lines and the return line
8an for the supply

View attachment 1241765 View attachment 1241766 View attachment 1241767

 

[INTMD8]

On my 69 Charger I'm just using the original vent tube. It attaches near the top of the fill tube and goes through a grommet in the floor, open to atmosphere inside the frame rail.

All other vent ports I have blocked off.

That's with a Walbro "hellcat" 525lph pump running full voltage all the time.

I don't think anything else would be needed. If so, could run the factory configuration with a bigger tube from the filler down through the frame.

Don't see the need on a Charger to run anything up into the sail panel. For cars that do, I would loop it up into the sail panel then back down through the floor/outside so you aren't venting fumes inside the car.

 

[69ChargerR/TSE]

So I think I have a plan….
The problem I think is caused by the tank filler being located on top of the fender. The vents (air inlet and expansion vent) need to be higher than the filler. The only place higher than the fender top is up inside the sail panel / rear roof support.
So here’s the immediate problem, I need to cross the frame rail with the vent lines.
I dont want to go under as that would created a line trap.
Unless I think of something else I’ll need to drill 2 3/8” holes in the frame rail.
I’m open to a better idea if anyone has one! The tank vents are shown in top of the photo.
Thanks in advance for any further ideas……
View attachment 1274812

Looks similar to a California ECS vented tank.

 

[not so famous bob]

So it turns out, the stock cap is not vented at all. It’s solid and spring loaded. A tank vacuum will seal it tighter.

I have no idea how a stock tank gets vented.

A new tank for EFI will definitely need a new vent and pressure relief system.

After looking at this some more,

I’ve decided to run 2 x 3/8” lines from the tank.
The first will be for air inlet and will have a check valve near the tank. I intend to run it up behind the sail panel to a point higher than the fill neck and terminate it with a small air filter. This line will keep the tank vented during hard acceleration. The check will also serve as a rollover valve as nothin will be allowed up the vent from the tank by the check.

The second line will be for pressure relief and will be checked opposite of the first. Only tank pressure buildup is allowed down this line. It will follow the 1st up the sail panel to again be higher than the filler neck but then it will continue back down to below the car (to keep out fumes). This line will equipped with a T at the top and a check valve to break any siphon that might get started. The exit will be lower than the tank so in the event of a rollover the bleed off tube will be above tank level which should keep the gas contained anyway.

Haven’t started the pluming yet but thought I’d share the plan as I can’t find much specific detail on this topic.

Thanks for your thought or further comments!

View attachment 1241738 View attachment 1241739 View attachment 1241740

I did that with my tank , but didnt vent it in the trunk , no filter ,
run it up hi , and put a coil or two in it , and run it back down thru the trunk floor , :same as a roll over valve , vented , and outside the trunk !
I used the top vent coming out of the tank , "inside its above the fuel level ...