Magneto Lag angle

Could someone explain what the lag angle is so my feeble brain will understand? Some of us Kaintuckee boys are kinda slow but most of my friends do wear shoes now. Well most of the time anyway. Especially since the walmarts won't let ya buy nuthin wit no shoes on.

Quote from The Magneto Ignition System by John Schwaner of Sacramento Sky Ranch. www.sacskyranch.com "the purpose of the impulse coupling is to snap the magneto through its firing position so it produces a spark even though the engine is slowly being cranked. To postpone the snap until the piston is near the top center position so that ignition is retarded to prevent kickback. At cranking speed the spring loaded flyweight on the impulse coupling catches on the stop pin. This stops magneto rotation and winds the impulse coupling spring until the drive lug on the coupling body trips the flyweight, disengaging it from the stop pin. Energy stored in the spring accelerates the mag through the firing position. The rotational distance between stop pin engagement and drive lug engagement determines how far the engine turns until the magneto snaps. This is the "lag angle."

In other words, if your magneto is timed to fire at 25* BTDC, you would need a lag angle of 25* or more to get the magneto to fire at TDC or after for starting.

OK, thanks fellas.