Hit and Miss

The latest project here under the Shadetree is this old hit and miss engine. It's on what's left of an old Economy Tractor. We'll have this thing popping and hopping real soon. These things are a blast to hear run. They are quite primitive with nothing mechanical operating the intake valve. The only thing that opens it is the vacuum created by the intake stroke thats sucks the valve open and draws in air and gasoline.

It has a governor that controls the speed of the engine by holding the exhaust valve open and the engine freewheels until it slows down enough to let the exhaust valve operate. It will then fire once or twice and go back to coasting. That's where the hit and miss moniker comes from.