Best way to vent a single nippled tank

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Markzilla88

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I’m attempting to fix the previous owners shotty job to vent the gas tank on my 72 Demon and am looking for opinions.
The tank has 4 vent nipples on it. 3 of them are crushed closed. The remaining one has a short 4” piece of fuel line that points to the ground. When I fill the demon up, it dumps fuel out of the fuel hose until, I assume, the fuel in the tank gets below that point.
I was planning on running a new piece of fuel line from that nipple to a point higher then the fill neck to vent the tank and prevent this fuel from spilling out.
The roadblock im hitting now is where the heck to run it to... the filler neck does not have a return port on it to hook into. It’s just a straight shot down to the tank. So I was thinking the only place taller then the top of the fill neck is in the trunk. Now the problem I imagine is that the trunk and cab of the car will smell very strongly of gas if I do that.
So I’m looking for opinions and help of where to run that vent line.
Thanks
 
Use the filler neck out of a 69 Dart. They have a vent hose that runs from the top of the neck thru the trunk floor to open air. You could use that open connection to run that vent hose to.
 
^^Or modify your neck^^ Otherwise, you need to get that "nipple" up as high as you can, and not sure where you would end it at the rear. Otherwise, run it clear up front, high in the engine bay. You could plumb it into the non pressure side of the PCV system (air filter bonnet) to contain fumes

You cannot just run it, say, up high in the trunk, then down again, because it will make a siphon. The way that the 69/ earlier stuff was done forms a "vacuum break"

The 60/ earlier system tapped into the filler up high, went up against the top of the rear quarter, then down along the filler tube, through the floor gasket, and ended (open) in the inside of the rear frame rail. This WILL siphon in extreme cases.......such as filled clear to the top, and parked on a severe sidehill with the filler neck on the lower side. But it will only siphon until the vent tube opening into the filler tube is "above water" and then it will "break."

242yckm-jpg.jpg
 
Markzilla88 said:
I’m attempting to fix the previous owners shotty job to vent the gas tank on my 72 Demon and am looking for opinions.
The tank has 4 vent nipples on it. 3 of them are crushed closed. The remaining one has a short 4” piece of fuel line that points to the ground. When I fill the demon up, it dumps fuel out of the fuel hose until, I assume, the fuel in the tank gets below that point.
I was planning on running a new piece of fuel line from that nipple to a point higher then the fill neck to vent the tank and prevent this fuel from spilling out.
The roadblock im hitting now is where the heck to run it to... the filler neck does not have a return port on it to hook into. It’s just a straight shot down to the tank. So I was thinking the only place taller then the top of the fill neck is in the trunk. Now the problem I imagine is that the trunk and cab of the car will smell very strongly of gas if I do that.
So I’m looking for opinions and help of where to run that vent line.
Thanks
Click to expand...
I used one of these. Made a bracket and mounted up on the inside of the rear frame rail.
Remote Mount Rollover Vent Valve
 
Lol gotta get people’s attention somehow!

I’d like to get something going for the car sooner then later so I can drive this thing before winter hits, so I may just get a long piece of fuel line and vent it into the bottom side of the air cleaner or try that rollover vent valve mounted to the frame. I guess it just needs to be higher then the fill neck right??
 
You want it as high as you can get it. Remember, sometimes you park your car pointing downhill LOL
 
Markzilla88 said:
Lol gotta get people’s attention somehow!

I’d like to get something going for the car sooner then later so I can drive this thing before winter hits, so I may just get a long piece of fuel line and vent it into the bottom side of the air cleaner or try that rollover vent valve mounted to the frame. I guess it just needs to be higher then the fill neck right??
Click to expand...

Fuel Tank Venting
 
Make a u shipped piece of tubbing the same size as the one coming out of the tank. Run the tube up into the trunk then back out . Connect on end to the tank the other to open air the top of the u will be higher than the tank and it will vent well
 
dano said:
Would a vented cap work temporarily?
Click to expand...
Nope. You'll end up with gas all over the side of the car any time you drive with the tank more than about 1/2 full. (Unless you never take corners and always drive on level ground.)
 
Markzilla88 said:
I’m attempting to fix the previous owners shotty job to vent the gas tank on my 72 Demon and am looking for opinions.
The tank has 4 vent nipples on it. 3 of them are crushed closed. The remaining one has a short 4” piece of fuel line that points to the ground. When I fill the demon up, it dumps fuel out of the fuel hose until, I assume, the fuel in the tank gets below that point.
I was planning on running a new piece of fuel line from that nipple to a point higher then the fill neck to vent the tank and prevent this fuel from spilling out.
The roadblock im hitting now is where the heck to run it to... the filler neck does not have a return port on it to hook into. It’s just a straight shot down to the tank. So I was thinking the only place taller then the top of the fill neck is in the trunk. Now the problem I imagine is that the trunk and cab of the car will smell very strongly of gas if I do that.
So I’m looking for opinions and help of where to run that vent line.
Thanks
Click to expand...

Go ahead and run it around the tank and up into the trunk, bend 2 coils in it and run it back thru the floor right beside the way u came thru, and down below the tank.
I DID MINE THAT WAY AND HAVE HAD NO PROBLEMS W/ IT , MUCH UNLIKE THE BRAND NEW 68 FASTBACK I BOUGHT IN 1968 , IT ALWAYS OVERFLOWED AT FILL UP, THIS DOESNT ----
 
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