Can anyone tell me the size of the fitting used on the hard fuel line from the rear of the car to the fuel filter under the bonnet? It "seems" to be 1/2"-20 but I want to be sure since we obviously don't want any fuel leaks!

Thank you.

Lin

 

Lin it may well be 1/4" BSPT

Specs are :-
19 TPI 0.518" OD

I will try and find a definitive answer for you

 

I can't find a definite answer, but the balance of probability is 1/2" UNF x20 as you thought, this was common on AC delco parts from the 40's to 80's, also used on Stromberg carbs, Delphi fuel filters use the same thread, and the nuts and olives are freely available on the web, but I can't find any of the correct fittings in the 1/4" BSPT, so I would go with 1/2" UNF, you must have a spare bolt you could try ?

 

Jon,
Yes I tried a 1/2"-20 nut on the fitting and it seems to work just fine, but I just found it hard to believe that this fitting would be a UNF thread.
Lin

 

I thought that too, but it turns out that its a very common thread size, the brake fittings are 3/8" UNF, so it does kinda follow.