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Tom Phillips,     Broken Arrow, OK     4/25/2008

Propane Hit and Miss

I have recently redesigned my first Hit/Miss engine (view that engine) and will share the results of that with you.

Now, the flywheels are 9" and two pounds heavier than before. The governor has totally been redesigned - new weights & springs for better control of speed. The fuel has been changed to propane and the mixer re-jetted to .058" and adjustable. The ventura is 1/4" so the vacuum is high enough to pull propane from the demand regulator. I made a demand regulator from FAME plans (plans are tip 3)  (that works superbly) and used an adjustable camp stove regulator on the tank. I also made a muffler for it.

    VIDEO 1 (Windows media file). 


Most other parts are used as the original except rebuilt. It has been named "Hopper" because it fires so hard and has little weight with the all aluminum frame, it will walk all over the table unless strapped down. 

These are the parts that haven't been changed from the original built March 2006.

 The electronics are made from a Jerry Howell buzzcoil kit with hall effect sensors for timing and spark saver circuits. And uses his exciter coil with a 6 volt battery.  

The bore is 2 9/16" and stroke is 1 3/4". The head is my design using valves from the Briggs cut down in length to fit the head. The cylinder, and head are all aluminum from bar stock. The compression is 5 - 1 with a teflon head gasket. All of the bearings and pivot points are oilite bronze.


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