Fuel tank venting

[nbracken]

My fuel tank has the flush mounted locakable filler and it seals very well. So well that i can sometimes hear the tank popping in and out as it expands contracts. I have no breather - I used to have a different type of cap that had a breather incorporated.

Any ideas on how I can easily get the tank to breath through this type of cap? Or any other ideas on how I can get my tank to breath. Removing the tank is not an option as that is a body off operation. Not practical on my kit.

Tx

[ColinH]

Hi
GD have the same type of fuel filler. I was recommended to drill a hole in the filler neck and use a combination of brake coupling and a short run of brake pipe to make a breather pipe that runs down from the filler neck out through the bottom of boot into fresh air.

Sorry I can't give a precise description of the fitting but is basically a compression fitting to grip the brake pipe on one side with a male fitting on the other side that screws into the alloy filler neck. I'm sure you could work it out if you had a rummage through a tray of brake fittings.

I also used a dollop of Blue Hylomar around the fitting to make sure that I got a good seal.

Seems to work OK

Hope this helps

[ColinH]

Hopefully this picture is clearer than my clumsy explanation
Cheers

[nbracken]

Colin thanks.

I was looking at the Think Automotive website and they have some valves which fit into the filler neck and do the same function.

[madjohnny]

Dax suuply a drilled out bolt/nut which fits through a hole you cut in the filler pipe.
You just connect a piece of flexible pipe onto this. I would says it's probably an M6 or so.

[Robin427]

I was very kindly given a small fitting by Trevor - it consisted of a hollow cylinder with an M6 thread on one end. I drilled and tapped a hole in the filler neck and then ran a small length of fuel hose from the fitting to some copper brake pipe which exits the boot through one of the rollbar holes

[neil still building it]

you could also add one of those little fuel filters in line too,(this would act a little like a buffer/damper to help slow down in and out flow of gasses and perhaps siphoning if you get a bit of sloshing if you don't have enough baffles)
hopefully it'll stop spiders going in and out too and even setting up home possibly blocking it HE HE
neil

[dingocooke]

You can buy a one way vent valve, intended for bike racing, fits inside 6mm rubber tube, they cost £4.99, weigh about 0.5g. Black nylon.

[wilf]

Whatever arrangement you utilise, stop and think about it - would it allow fuel to spill if the car was inverted?

A breather pipe that runs downwards, and exits below the level of the "floor" of the tank would be fine.

I did have a US friend who inverted his Cobra replica on a track day, and he told me of how he nearly messed his trousers as he hung upside down in his harness listening to the sound fo fuel pouring out of the tank.

Oil pressure cut off for elec pumps is a good idea too.

[neil still building it]

a loop in the pipe UP and THEN down will help pretty much stop this of course ,during an upside down event...assuming everyone knows to do this.....
- or not?
neil