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IHC H-4 Magneto No Spark

W

Wayne Koos

New User
Farmall A magneto has no spark. The 1945 tractor has set for 5 yrs. Always started immediately before. I've replaced the condenser & points. Coil shows 1300 ohms resistance. Is that enough? I've spun the engine fast via 12 volt. Any suggestions?
 
Does the impulse coupling trip like it should while cranking the engine?

Spinning the engine fast on 12 volts doesn't necessarily double the cranking speed.

Yes did you clean points after setting the gap?

If you have a kill switch make sure it's working as it should!

If you have a kill switch disconnect it and connect an Ohm meter to the engine block and to the magneto kill terminal then rotate the mag.
Your meter should show continuity then no continuity as the points close and open. These are a few things I would check.
 
Yes - points clean. The impulse works well. Is coil bad?
I've a used coil that was working in another tractor with 1200 omhs resistance so figured the coil was OK.
 
You had to take the cap off that covers points . Did you get it lined up right when putting it back on? It could be 180 degrees if it got
turned.
 
About 40 years ago my dad had a 40's cub. Mag had a problem. Lost
spark after about 10 minutes. We had no idea how to repair it or
where to get parts. So I used points and condenser and hung an an
external coil. Worked that way for years.
 
There is a wire that connects to the condenser that can hardly be seen under the condenser I believe it is green, and is often missed when changing the condenser . . If I emember eight, two wires are connected to the condenser. Don't ask how I know this.
 
I tested the kill terminal to ground as you suggested. The ohms jumped to 500 at impulse but only on every other impulse. The in between impulses the needle just wiggled. Why would that be?
 
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