No guarantee, but if they were used in early Fords, they almost surely would be imperial dimensions. Standard coarse threads would be 5/16-18; I don't remember fine off the top of my head.

Tks for the reply Tornado.

I have found 5/16" happens to have 18 standard indeed, but that is too coarse. There is also 20, 24, 27, 28 and 32. Not simple.

I have found a stud with 2 different threads and one seems to possibly work, although the original salvaged banjo part has been forced and the thread is not confirm any more.

I will go to search for a bolt and if I am lucky maybe some banjos here on the island. hmm?

Take care. D.

Being a Pomgolian motor of a certain vintage you may find them to be Whitworth (BSW)which is an alternate Imperial standard. If its not Whitworth it may either be "Gas" thread or perhaps UNF.

There are no direct metric equivalents.

Have a look at historical truck and/or machinery forums preferably ones that deal in old English stuff like Leyland/Bedford/Foden/ Perkins etc. Asking the question there may lead to the appropriate responses for you.

There are also forums dedicated to diesel motors, I have an issue trying to put the site links in the thread but try googling diesel boat or british diesel.

Thank you.

The banjo bolts I took out the injectors are 5/16" with 27 TPI. The new injectors have a banjo of 5/16" 24 TPI. Had to be exaxct the same injectors.

I found Perkins Banjos with 27 TPI and have put a 24 TPI thread on it (re-cut) It is not perfect, but it seems to hold the pressure very well.

Try googling Banjo fittings.

Big problem to find these. Had one address @$59.00 per piece.

I found a perkins diesel in a bobcat and bought the banjos and the rack for $20.00. Been lucky today. Thanks