Non-standard thread tolerances in old engines

53/5/1: Chasing threads

Regular contributor Andrew Mackey responds to John Burgoyne (53/3/1: Thread standards) in the April/May 2018 Gas Engine Magazine. Andrew writes:

I too have run into problems with inconsistencies in threading. When I restored my Charter-Mietz, the threads on the fuel pump, injector, as well as other connections were tapered pipe fittings. Although the OD of the fittings was the same as NPT US pipe, the threads