Gents – I am running a Webber carb with a return pipe and building my own tank. Is a breather pipe required, if so does it need a lock off valve as fitted to the Sierra?

As Shrewsbury is the nearest test centre to North Wales, has anybody got any comments or advice????
Thanks

you will still need a vent pipe, as you use fuel you will need to fill the space left by the used fuel, hence the vent pipe will let air in as the fuel goes out, i don,t know if you need a one way valve in the vent pipe for the sva but to me it makes sense to fit one anyway..