Jason--I know that it has to move back and forth. My experience so far with three different model hit and miss engines has been that whatever it is that moves into place to hold the exhaust valve open has to move into place and stay there until the engine slows down enough for the counterweights to move it out to let the engine "hit". This is a different kind of animal, as it seems to me that the rod would be constantly moving back and forth with every revolution of the camshaft. I just watched a couple of youtube videos of "domestic stovepipe" engines which have this type of governor mechanism.--and yes, that rod is constantly moving back and forth. It does seem to work very well however to give the hit and miss action. Maybe it's an issue of the amplitude of the movement.