The H4 mag impulse retards the timing by 35 degrees when starting, which if you have your mag static timed correctly, draws it back to TDC, or 0 advance. If the mag is in good shape, it'll fire no matter how fast the engine is spun by the starter. The impulse only activates below 150 RPM, above this, it is turning fast enough on its own to spark just fine, and the timing is advanced to 35 degrees BTDC. The retard function is only for hand crank purposes, to avoid a kick back and a possible broken arm or worse! Kick back has never been a problem when using a starter however. The engine will crank over and start using a 6 volt starter turned by a 12 volt battery even with the starting timing set to 45 degrees advance, because the starter is strong enough to turn the engine right on through any possible kick back it might try to do. The only symptom you "might" run into would be slow cranking due to too much initial static timing, the old familiar "wroo ... wroo .." situation, when the engine is already hot. The cure for this is to retard the static timing a little until it starts fine when hot too. It usually takes over 50 degrees initial advance to cause this issue when hot, but boy will she ever start easy like this when cold!
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Today's Featured Article - Choosin, Mounting and Using a Bush Hog Type Mower - by Francis Robinson. Looking around at my new neighbors, most of whom are city raised and have recently acquired their first mini-farms of five to fifteen acres and also from reading questions ask at various discussion sites on the web it is frighteningly apparent that a great many guys (and a few gals) are learning by trial and error and mostly error how to use a very dangerous piece of farm equipment. It is also very apparent that these folks are getting a lot of very poor and often very dangerous advice fro
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