A few thoughts...... some good advice from others here. The mag is your problem, or the way you are installing it on the engine. The timing gear is NOT the problem. Be sure you are setting the timing of the mag correctly on the bench and THEN make sure the engine is at the specified timing, usually 20 or 25 degrees BTDC before attaching the mag to the engine. I have seen people set the engine at TDC when installing the mag, and then it is impossible to time it correctly. This may be your problem.
IF you do remove the engine gear, be sure to place a rag underneath it inside the accessory case. You don't want the rubber cushions falling into the engine, and there is a bearing that is press fitted into the crankcase that SOMETIMES comes out with the gear and other times it doesn't. You don't want it falling into the sump either.
Built RV-4, RV-6, 2-RV-10's, RV-7A, RV-8, Prescott Pusher, Kitfox Model II, Kitfox Speedster, Kitfox 7 Super Sport, DAR, A&P, EAA Tech Counselor/Flight Advisor, CFII-ASMEL/ASES, EAA Homebuilt Council
Mallards Landing, GA (GA04)