1973 Evinrude Norseman 40 HP Service Manual, Page 29Get this manual
HIGH TENSION LEAD SHORTING SWITCH
Figure 4-10 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 cent er leg induces an electric charge in the coils The current in the primary coil flows through the closed breaker paints 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 th coilAt this preCise moment, the breaker paints are opened by cam on the engine crankshaftThis interrupts the flow of current in the primary current, nd 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 pointsTh 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