I've worked on lots of stovebolts - never seen one with 10mm plugs in it before. My '50 was as original as they come and it has the standard 14 x 1.25 thread plugs in it.

In fact - I've never worked on any engine with a 10mm spark plug in it. And that's saying something - been building engines of all sorts for 35 years.


1950 4100 - unrestored and driven weekly for almost no reason at all.