An engine by Mick Cherry. The open crank farm engine was made after I had purchased a new lathe. I thought I would build something simple just to iron out any problems.
The outcome is a terrific little engine, dead simple to make, the main frame is all made from 1/4 ally sheet screwed together. The only tricky bit was the inlet valve, it’s the automatic type, and with it being a relatively slow running engine I had to get the spring strong enough to snap the valve shut, but weak enough for the piston to suck it open to allow fuel in.