by Jim Arnott
"I've got no spark at my coil and can't figure out why. I have checked
everything I can think of. I have replaced the coil and condenser with
new ones. I swapped out the distributor. I ran a hot wire from the
battery to the coil to eliminate the ignition switch as a possibility."
My guess would be a grounded (or open) set of points. (Two piece points? did you forget the fibre washer under the spring?) First check for power to the coil. If you have 12v there, then manually open the points and check for spark from the coil. If no spark, remove the wire from the points and manually "spark" it to ground. If spark, then problem is bad points or condensor. If no spark, then the problem is coil or the wire to the points. To check the coil, disconnect the wires from it and take your multimeter (You do have a multimeter, don't you...) and check the resistance between the 1 and the 15 terminals. I don't remember how much it should be, but it will be a bunch. 20k ohms? It shouldn't be open or shorted. If it is, replace it. To check the points, rotate the engine 'til the points are open and check that the fixed point has 0 resistance to ground and that the movable point has infinate resistance to ground. Bad condensor? The only way to check that is to replace it with a "known" good one. (A known good one could be the one that you took out of the bus the last time you tuned it and it was runnung.) The Kettering ignition is really pretty simple to troubleshoot.
To quote L.J.K. Setright:
"...a battery to supply electricity, a coil to transform that low voltage supply to a much higher electrical pressure, with the assistance of a contact breaker which triggers it to produce a very high voltage pulse, which is led , via a distributor, to the appropriate spark plug where the pulse comes across the gap between the electrodes, igniting the charge in the process. The only other essential is a condensor, wired to the contact breaker to prevent excessive arcing or sparking across the points as they open to trigger the pulse from the coil..."