1971 Evinrude 40HP outboards Service Manual, Page 30Get this manual
HIGH TENSION LEAD
SHORTING SWITCH
Figure 4-1D As the poles of the magnet sweep further along the flux in the center leg breaks downThe rapid development and collapse of flux in the center leg induces an electric charge in the coilsThe current in the primary coil flows through the closed breaker points and sets up magnetic flux of its own in the center leg of the coreThe direction of the flux momentarily opposes the establishment of reverse flux in the center leg as the poles of the flywheel magnet reach to the center and third leg of the coilAt this precise moment, the breaker points are opened by cam on the engine crankshaftThis in terrupts the flow of current in the primary current, and the opposed flux in the center leg collapses To hasten the collapse, condenser in the primary circuit absorbs the current which would otherwise arc across the opening breaker pointsThe rapid collapse induces current of sufficient voltage in the secondary circuit to arc across the spark plug air gapCONNECTION TO PRIMAR LEAD AND BREAKER POINT