Vented Gas Cap

[2fine69s]

Hey guys,
I have a 69 Dart, that came with a vented tank. When I replaced it, i put a non vented system back to reduce excess lines etc. and it just plain looks cleaner. My question is: Is there a vented 67-69 Dart gas cap available? If not, I'll have to modify my vent tube ( which I can do it's just more work). Any suggestions?
Thanks,
Martin

 

[67Dart273]

Do NOT use a vented cap. None of these cars used vented caps except the ones 70/ later with the evap emissions (carbon can) system, and these were not truly "vented." They were called "pressure vacuum" caps and had what amounts to pressure relief valves.

The right way to do this is exactly how the factory did it up through 69----a vent fitting up high on the filler, which goes up even higher in the rear quarter, makes an upside down U and goes back down and ends pointing down in the rear frame rail.

All a vented cap will get you is............fuel all over the side of the car

What is the one in the photo and why do you have to modify it?

 

[2fine69s]

Do NOT use a vented cap. None of these cars used vented caps except the ones 70/ later with the evap emissions (carbon can) system, and these were not truly "vented." They were called "pressure vacuum" caps and had what amounts to pressure relief valves.

The right way to do this is exactly how the factory did it up through 69----a vent fitting up high on the filler, which goes up even higher in the rear quarter, makes an upside down U and goes back down and ends pointing down in the rear frame rail.

All a vented cap will get you is............fuel all over the side of the car

What is the one in the photo and why do you have to modify it?

I guess my question is: where does the outlet end of the vent tube go through the trunk pan? Should there be a hole in the trunk pan for it? Should there be a flex hose attached to the vent tube outlet and where would it go under the car?

 

[67Dart273]

Yes. Goes through the rubber cover around the filler, there is normally a hole right in the top of the frame rail. The tube simply ends, open ended, inside the frame.

This is an elegant, simple, system. You have to understand how it works. Because the vent is connected so high on the filler, this means the filler must be REALLY full to cause any siphon action out of the vent tube. And since the filler is tall and slender, this means maybe 1/2 cup of gas is all "worst case" you will siphon out. That is, unless it is very very full and you somehow parked with the filler pointed downhill at an extreme angle. Even then not much is likely to siphon.

 

[Snake]

I always wonder about that vent tube,1 would think it would cause gas to evaporate with the price of gas does it?