am i right in thinking that a standard one way valve ( letting air into the tank,but stopping anything from going out of the tank) will fail iva? i have heard of people passing with them and people failing with them. if they are not ok how do you mount a genuine roll over valve (like the ones in merlin) when they have a threaded union to connect to tank? as the tank has no threaded outlet and valve needs to be verticle!
can you use a small piece of hose from tank to valve and mount the valve vertically onto a chassis member, using a hose clamp to connect the hoes to the threaded end of valve? or are special unions available? what are your thoughts on this subject? cheers

I used one from a trials bike, small plastic one with push fittings both ends, couple of quid from local offroad bike shop.

are they a proper rollover valve or are they a 1 way valve?

You need this one. Two way valve lets gas in and out but not fuel out.

but thats almost £10 more than the one with 1/4" - threaded end. this is what i didnd understand? whats the diference?

You need something that fuel vapour does not rot, just nip one out of an old brake servo

I used the one that is fitted to the top of the tank in a Ford Fiesta (you can get at it from under the rear seats). In the photo, it's the round white bit at the bottom right of the tank with the stub of fuel pipe coming from it. Cost nothing from a scrapyard, and designed for the job. 2 way breather with rollover cut-off.

The little white cap at the end of the hose is a silencer designed for pneumatic systems. It lets air in and out, but really helps to cut down any fuel smells.
HTH,
Ed.


[Edited on 18/3/11 by Madinventions]

Not sure if iva proof but I used the standard sierra item. has a ball inside to cut off fuel in a roll over.

Should be IVA proof if they're type approved?

the ones i saw at merlin were twin ball item,but had to be mounted vertical!

Hi.... I have a vent for my tank built into my filler... I had a quick look in the IVA manual but couldn't see anything about having to fit a roll over valve to cut the fuel or anything... Are there specific requirements?

Dave B