I need to put a vent in the fuel system to allow for release of pressure or partial vacuum. Thoughts are to use the valve from the Sierra, which when the correct way up, will operate normally, but when upside down will shut off.

In the sierra this was fitted to the filler neck. As my return line from the carb is to the top of the tank I was wondering about using a T piece in line with this and then fitting the valve higher then the return pipe.

Can anyone advise if this is a daft idea and why?

My other option would be to connect a small tube to the top of the filler, problem is if I braze it in place I could never remove the assembly and not sure how good a seal I could make on the 2 inch round filler section.

I am using a deck filler!

Cheers

Adrian


[Edited on 12-7-09 by AdrianH]

If the tube between the filler neck and the cap is plain butile rubber can you not tap into it using a bolt-in heater take-off (see car builder solutions) and run the breather pipe from there?
Tapping into the return pipe does not seem like a good idea as it's presumably still pressuried.
Cut-off valve not totally necessary unless you are planning to race. Just ensure the breather exits the bottom of the car.
HTH.
Cheers, Pewe

Sorry for the delay been away for work.

The fuel fill pipe I have is ribbed so may not have a large area to seal against. Your point of not needing a valve is a good one, re-reading the IVA book I wonder if a small bleed hole drilled in the cap would do?

Adrian

[Edited on 14-7-09 by AdrianH]

Can't really comment on the IVA aspect of a bleed hole but I've always felt that a breather exiting under the car is better. If you did have the mis-fortune to invert it the fuel is less likely to leak out of the breather.
BTW if using an electric fuel pump is there in interia switch somewhere in the system i.e one that cuts the power to the pump in the event of an accident (partic. important where high pressure pumps for fuel injection is concerned)?
Cheers, Pewe

Hi Pewe;

On the present set-up it is a mechanical pump on the engine.

I have a bit extra time to spend on the car for a while so will try to fabricate something to fit the deck filler to fit an extra tube and valve.

Cheers
for the response.

Adrian

I have used the valve from my sierra. if you cut of the lugs it mounts quite nicely with a tywrap and tywrap mount. I have mounted mine as high up under the bodwork as i possibly could.

I originally used a T pice of the tank return from my swirl pot but soon realised this was not the way to do things as fuel; returning to the tank will effectively block the breather off.... if you follow my rather muddy logic....

in the end I put a large rivnut into the top of the tank and a piece of threaded tube into that and glued it all up with a proper fuel safe sealant. that gave me a simple connector for my breather pipe.

[Edited on 20-7-09 by DaveFJ]