no spark on 47' farmall cub

[jakieboy]

I have a 1947 IHC farmall cub that has a j4 magneto. after not using it for a while because of a carb issue I tried starting it and she wouldn't fire. I checked to see if I was getting spark, and found no spark across the plug gap. I figured it must be the coil because the points looked brand new, I have put a new cap, rotor, and new wires on it and when I replaced the coil I cleaned up the whole magneto and checked to see that the wire going to the mag from the switch had continuity. I'm at a lose for what's wrong. Can anyone suggest a fix?

 

[Stimw]

Magneto's must have an air gap and some can be adjusted.
Without the air gap the voltage can go high enough to arc and ruin the mag coil.
Does yours have an air gap?

 

[LouNY]

If you roll the engine over slow can you hear the impulse mechanism working in the mag?

 

[DJ54]

I see you've replaced everything except the condenser. That could be the culprit.

But just for giggles, unhook the wire from the mag, to switch, on one end or the other, then try it. Mag end would probably be easier, in case it fires, just leave the switch in the off position, then touch the wire where it attaches to kill the engine. I've had the switches on my BN & A, apparently get some corrosion inside, and would short the mag out, even though in the on/run position. Some WD-40 sprayed around the shaft of the switch, when in the on position, then twist & turn for a bit seemed to fix the problem. This seemed to happen mainly when they were left outside, and got rained on.