Hi Grey,
Presumably the 10cc of oil gets through to the timing gears and camshaft? With a typical glow fuel with 20% castor oil, does that dilute the sump oil?
I had a similar problem with the conrod fouling slightly,on a Sperry 5cc Diesel, and I cured that with some local scraping.
I will look up the site of the cam machining right away.
Keith