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Crank operated lever controls rotary valve and fries brain!

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crueby:
Yes!  And the size and positions of the openings in the rotary  valve will need to be determined  with the length of the valve cranks, they all need to work together. Nice detective engineering.

PaulR:
I think this is about right now. The crank pin is at 10mm and the valve pin at 12mm. With the valve centre 80mm from the crank axle, the valve rod comes in at 80.5mm and the lever at 15.5mm, giving an arc of travel of 100 degrees. Putting the centre of the piston travel at 50mm from the crank means there will be little dead space behind the piston at tdc (which I'm guessing is a good idea for a single acting engine?).

PaulR:
Thinking again about this now the latest project is almost finished, it strikes me that it could probably be simplified by having two cranks rather than the lever arm controlling the valve at the back which would make it easier to get the valve flats (or holes) in the right place. That would make it easier to make the valve. The only downside I can see is the length and extra weight on the main crank. A wrist pin in the piston as per the original post would also be easier than the cross-head I've hinted at.

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