Hi Norm, Sadly I don't have a turner and the local engineering place has a minimum $100 on any work they do.
Ironbark, yes you're right, they are 1/2" BSF. I found some that are the right diameter, but have a smaller thread. So I guess I could put them in the drill press, drill them out to a larger diameter and then thread them? As you say, will take a lot of time and effort and I don't currently own any BSF taps.
The alternative might be to use a different cup. I have an old Southern Cross starter cup that is the right diameter to fit neatly on to the shaft. Then I will just need a standard 1/2" BSF nut to fasten it down to the flywheel. Bit sad that these nuts have disappeared. Tecumseh seem to be all UNF so even if you find one the right size the thread is still a problem.
