"The correct terminology is 'atmospheric engine'. But anyway, here is a 'flame eater' engine you can build any of four ways: (1) - Air Cooled Side Crank as shown, (2) - Water Cooled Side Crank, (3) - Air Cooled Center Crank or (4) - Water Cooled Center Crank!
The air cooled engines have an optional belt driven cooling fan which provides cooling for long running sessions. The engine runs fine without it. With the fan, the engine will run all day long and never get hot. But long runs or not, the fan also adds much interest to the engine.
All four versions use my oscillating (twisting) side shaft mechanism to operate the head valve. My unique valve seat is of self lubricating non-metallic material which greatly reduces valve sliding friction and virtually eliminates wear. The engine speed range is from 60 to 600 RPM or so." - Jerry