Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Up until my ignition black box packed up, my M90 engine ran faultlessly on both zippo, ordinary unleaded petrol and a mixture of both. I don't think fuel is at the root of Raphael's problems with his engine. **

The variables that decide whether an engine will run are:

Compression
Fuel/air mixture
Proper energy of spark
Spark timing
Valve timing
Free movement of engine parts (ie not binding up and absorbing all the energy).

I don't think there is anything else that can stop a working design from working.


My M90 worked great, then it didn't when the ignition unit started to fail. The failure may have occurred because while I was trouble shooting a sooted up spark plug, I may have inadvertently spun the engine over without the spark plug body properly earthed to the engine, because I had the plug outside while I was looking at the spark energy to diagnose the sooted plug. This leaves the HT energy to make its way back through the ignition unit electronics to ground and is a common cause of breakdown and failure in electronic ignition systems. Having been brought up in the robust era of contact breakers and tough as iron coils, I didn't take account of this inherent weakness.

** EDIT.
I have run a little two stroke oil in my fuel - varying from about 20:1 when it was brand new, to about 40:1 after it had run a little while. Mine spits out carbon coloured oil too.