UKIE,

Most K&B green heads were good running engines in the early/mid nineteen fifties. Manufacturers started making specialized engines and most general purpose engines went away. Fox had their EXCELLENT stunt .35, then came out with the "Combat Special" which ruled the roost for awhile. OS Max had their day, and Supertigre made excellent combat engines (although some had crankshaft problems).

Supertigre had so many different engines back then that only a picture could really identify it. For instance, I have, I think, the first generation G21-35. It has a removable front and back. I believe that it was one of the ones noted for breaking crankshafts.

Fox kept making improvements to their "Combat Special" and flyers knew the different models by MK-1, MK-2, etc.

Johnson made a good combat engine but some were more for stunt. I do not have any, so perhaps someone else will explain the differences.

George