[Edited on 3/2/06 by bob]
Rescued attachment MK Indy build pics 072.jpg
Hi All,
I have a small outlet from the top of my fuel tank, which is obviously for a breather pipe.
Can anybody tell me at what level the end of the pipe should be, ie, above the tank, below or what?
Also, should it have some sort of vapour trap/valve on the end to stop fumes escaping?
Many thanks for your help.
Dave
Best thing to do, or should that be simplest, is to take a bit of fuel hose and bend it through 180deg. Make the long end long enough to hang below
the bottom of the tank. The short end should attach to your breather. This way if you ever have the misfortune of ending up upside down you wont have
petrol leaking from your tank.
David
I've just got a one way valve on the top of mine,works fine and went through SVA ok.
[Edited on 3/2/06 by bob]
Rescued attachment MK Indy build pics 072.jpg
I used one of the 1 way valves on the stick Pinto induction system.
Either of the above will do the trick.
For what it's worth I usually use a piece of copper/kunifer brake line looped around the tank and terminated with an open end just below the
tank.
Thanks for the quick replies all, they all sound great ideas.
I'll probably combine the loop pipe and the valve.
Incidentally where can a buy a one way valve from?(save me trawling the net).
Thanks again.
All the best
Dave 
Think Automotive or Rally Design, both net based
Harris performance do a suitable one for £7.23 + vat 
laying in bed last night i actually had a thought about this.
with the one way valve nothing should leak, but im never one to take chances.
problem i see is if the car lands upside down it wont let petrol out, but what if the car lands on its side and the one way valve fails.
petrol everywhere!
My suggested answer to this is place the breather pipe along the length of the tank before it exits down to the ground. so that whatever way you land
the petrol will have to flow uphill to leak.
NS devs idea of looping around the tank is a good idea but you still have the possability of a leak if the cars on its side.
Oneway valve works on head of pressure --- won't leak no matter what way up the car is .
quote:
Originally posted by cornishrob
NS devs idea of looping around the tank is a good idea but you still have the possability of a leak if the cars on its side.
quote:
Originally posted by britishtrident
Oneway valve works on head of pressure --- won't leak no matter what way up the car is .
Thanks again for the info guys, it's a great help.
quote:
Originally quoted by RazMan;
But it wont allow air to vent fron the tank either - your tank will be inflated and go pop!
You should use the proper valve which lets air/vapour flow either way but does not let petrol through. There needs to be a way of air entering the
tank as you use the fuel and to allow air out as it expands when the car is standing on a hot day.
I did just loop my breather pipe over as others have suggested, however, I filled the car to the brim one day and drove off and home with a couple of
tight turns and parked the car in my drive and when I came back a couple of min later the fuel was syphoning out of the tank.
Keith
Suffolk
quote:
Originally posted by Dave J
Surely the one way valve will allow air into the tank when the pump draws the fuel out, so I cant see how the tank would either implode or explode.
On filling the tank the displaced air would rise up the filler. Have I missed something or am I being too simplistic?
quote:
Originally posted by Schrodinger
You should use the proper valve which lets air/vapour flow either way but does not let petrol through. There needs to be a way of air entering the tank as you use the fuel and to allow air out as it expands when the car is standing on a hot day.
I did just loop my breather pipe over as others have suggested, however, I filled the car to the brim one day and drove off and home with a couple of tight turns and parked the car in my drive and when I came back a couple of min later the fuel was syphoning out of the tank.
Keith
Suffolk
Ah now that clears it up nicely, thanks guys
All the best,
Dave
But then again!!
Better get my hassock out!
i fited one way valve to breather pipe then mounted that higher than the tank inlet. I figured that most of the time the car isnt upside down and more
often than not you can fill the tank and part way up the neck - hence higher is better. SVA man was happy with this.
As an aside hijack - does everyone else have bother filling the tank - pump keeps clicking off. Neck is 90deg flexi to back panel mounted cap.
quote:
Originally posted by DarrenW
i fited one way valve to breather pipe then mounted that higher than the tank inlet. I figured that most of the time the car isnt upside down and more often than not you can fill the tank and part way up the neck - hence higher is better. SVA man was happy with this.
As an aside hijack - does everyone else have bother filling the tank - pump keeps clicking off. Neck is 90deg flexi to back panel mounted cap.
quote:
Originally posted by Jubal
I'm considering fitting a slightly longer flexi hose to see if that helps
quote:
Originally posted by RazMan
If you mean the corrugated style rubber hose - that could be your problem because the flow is very slow due to the corrugations.
couple of things too think about........
I would defo fit a non return but also fit it as close too tank as poss, if the pipe gets ripped off in a collision then you have an open end
again.
filler cap, if this is fastened too the bodywork and the bodywork gets hit, damaged or ripped off in a collision then you have around a 2" open
end into your tank, I have seen this too an unfortunate soul, if your doing track days in your car i would be tempted too look at your filler cap
position and maybe even if its only a road car too, I know these aerocaps look nice on the rear panel but imagine what would happen if you got one up
the rear ???
Ive had a fair few offs in my time, the one at cadwell would have seen the filler cap off if it had been fastened too the bodywork and the more recent
one on the road would have had the filler cap off too.
Food for thought.
Thanks for that sobering thought!
quote:
Originally posted by NS Dev
Either of the above will do the trick.
For what it's worth I usually use a piece of copper/kunifer brake line looped around the tank and terminated with an open end just below the tank.
quote:
Originally posted by NS Dev
Either of the above will do the trick.
For what it's worth I usually use a piece of copper/kunifer brake line looped around the tank and terminated with an open end just below the tank.