Trying to ID this early engine. Two cylinder, two cycle, three port induction, 4 x 4 bore and stroke. I've been looking at many ads for Roberts engines and Elmore cars...close, but no cigar. I was hoping someone may have an idea. The crankcase is all aluminum with bronze bearings, cast iron pistons, three piece rods. Some have said marine engine, but with the crank starting pin and drive sprocket on one end and the flywheel key on the other, I am inclined to think early auto. Any ideas appreciated.