barit1,
As far as I remember the P&W radials used a "compensating cam" in the magneto to open the points and fire the plugs a calculated (and ground on the lobes) bit "too early" or "too late" just to allow for the fact that the pistons attached to articulating rods arrived @ TDC a bit earlier or later than a theoretical engine without articulating rods.
Ah yes, the Good Old Days with the Timerite stuck in #1 cylinder attempting to get the lights to wink on both mags together!! Who can forget the magic wand to find a crook (cold) plug?? Not easy to get the tip on the aft plugs of the rear row, especially the 28 cylinder nightmares we had come through from time to time.
