This is going to sound a bit stupid ..... How about selling spark plugs with no thread and let people cut their own threads
There are a bunch of standard plug sizes, if you start producing scale plugs then whoever picks up an engine second hand is going it up when they try fitting a standard plug.
Jo
They would be scale plugs on top with standard, modern lower end. I guess what I want to know is, is a 1/4 inch thread more common in a 1/4 scale engine or a #10?
If someone has to cut there own thread then they would also have to machine the ground strap at the bottom. I'm not sure anyone would be interested in them.
I just dont want to make a plug that nobody wants because it wont fit or needs an adapter.