ARUP

Hi Oberst- just think of a screw-on bottle cap but without the threads. Drill a hole in the center of this 'cap' so it fits the engine's crankshaft. Slip this onto the crankshaft and against/ over the thrust washer on the engine's crankshaft (just as if you were putting a propeller onto your engine). The 'cap' needs to be large enough in diameter to clear the engine's crankcase. It also needs to be long enough and 'strong' enough for a bearing to have a snug interference fit. The bearing's inner ring will 'capture' the 'cap'. An Enya or similar rear carb engine would work best for you will need the room for the dummy engine to spin. The dummy engine's crankcase needs(?) to be made of metal so it can be pressed onto the outer ring of the bearing. Remember, the dummy engine will spin up to fairly high rpm's so it needs to have good structural integrity against centripetal force. If not, you'll end up with a 'scale appearing' hole in your cowling!