Re: Mark 20 with bendix ign problem

[20mercman]

These Scintilla systems can be very finicky. They are notorious for dropping a cylinder, but to have no restart, 😕 I would make sure that you don’t have the plug wires reversed. The point gap is critical, and the spec. of .018 is a Maximum gap. The better number is .015 as it gives the magnet a tad more time to charge the coil. The other important factor is the air gap between the magnet and the laminations. .008 if I remember correctly. A loose upper bearing can cause fluctuations in the point and air gap. Another factor is that the magneto plate is not moving evenly on the crankcase. There should be a split ring spacer under the crankcase for the fingers of the magneto to ride on. This prevents wear of the crankcase and also helps to keep a true plane for the magneto to rotate on. There are also two spring loaded friction screws on the base of the magneto that rub along the outer edge of the crankcase. These keep an even drag on the case, but if the case is worn out of round, it can cause the magneto to change the point and air gap as it rotates. As I said, these are often difficult systems to get to operate, but they are worth the effort. I prefer the earlier Scintilla systems as was OE on the KE-7 as these had a different rotor, and the flywheel had the point cam. Some folks have ended up converting their motors to the Phelon system, (and I have done a few myself), but the parts to do this are very hard to come by, so do everything you can do first before going in that direction. Adding an auxiliary ground wire from the magneto plate to the block is always a good idea. There has been extensive discussion on this topic over on Johnsoldmercurysite.com and there are a lot of folks over there who have taken on this battle. Some have suggested that the new coils do not have as many secondary windings as OE, so they produce less maximum voltage. I can’t confirm this, just repeating what others have posted. The one thing I keep going back to, is that these motors ran for a long time with these systems, they should be able to run this way again.

Steve