A40 Farina Club

Hi all , I am after a locking petrol cap for my car it's a mk2 and I have been told it needs to be the vented type. Does anyone know where to get them from I would like it to be chromed if possible, kind regards Andy.

Do a Google search for "classic mini locking petrol cap" you will be spoilt for choice

Thanks Mike , once again you always help, appreciated, regards Andy

Gracious - why does a petrol cap need to be vented? I've always thought the tank needed to be able to hold the fuel without the danger of it escaping as vapour (which I understand is much more dangerous than liquid petrol)?

I guess because if it was a sealed system, as fuel was used, a vacuum would occur and collapse the tank.

Unlikely the tank would collapse Ed, nowhere near enough vacuum. The fuel just wouldn't come through.

Ah yes. I was underestimating the suction power of my Zenith carburettor!

Instinctively I don't believe the tank would collapse, but the numbers are interesting. I have not checked a tank size, but assume it's about 36x14 inches. Say 500 square inches. If we take a typical pump pressure of 4.5 PSI acting over 500 SQ.IN, that gives 2250lbs acting on the tank. Personally I would not set out to store a tank with a one ton load on top of it. Halve the tank size and I still would not store half a ton on top of it.

Well, I'm truly boggled. I had a look at Gab's "tin" fuel cap and it appears to be a solid curved top with a rubber seal around the circumference. No hole seems apparent, but it's been like that for 60-odd years so unless the tank is in fact sucked down to an inch thick (!) I'll leave well alone! and remain in blissful ignorance...

Well lads and lasses I am befoggled, baffleised and flabbergasted, I only wanted a locking petrol cap, was informed it should be the vented type. Now I have got a science lesson, a maths lesson, and history of fuel tanks and petrol caps over sixty years. The fountain of knowledge you lot have has frazzleised my tiny brain . However I have ordered a period locking petrol cap that is for cars of our make , model and year so will let you know if I go out and the car turns inside out due to the vacuum caused by the said petrol cap, and I come out via the carb 2 stones lighter because I have been vapourised. Thanks all, love the banter, the information, and help. Stay safe take care and my will all meet up sun so I can show you my new fandangeled, super dooper top of the range petrol cap. Lol. Kindest regards to you all Andy