The reason for the rpm increase with the C&H ignition is the timing..FPE times the 2.4 at about 18 degrees BTDC, retarded from where it should be...C&H retimes it at 28 and uses syncro spark to retard it for starting...A Ridge ignition timed at 28 degrees would work the same..The crankshaft on a FPE does not have a taper, uses a straight crank with a key...To retime the engine it is necessary to somehow rotate the prop hub on the crank to the right position..C&H uses a new hub, keyed in the right place...I have retimed a few 2.4s by leaving the key out and rotating the hub, then using 2 setscrews and some green 680 Loctite to keep it in place...
Works fine, increases rpm 6 or 800 from stock....Only FPE knows why a company would sell an engine with retarded timing, then offer another ignition with correct timing as an option.....