Re: 1940 Johnson HD-15 Magneto testing

[joesnuffy]

That’s good work!!!

I don’t think the grounding tab on bakelite would have to be right on the money just close since the points have to break to fire the plugs.

The only thing I can think of that you could check since bakelite was altered if it doesn’t run right or before you put motor back together is with your wire snaked to the magneto attach it to the points so you will know when points break using a multimeter or stevens tester in continuity mode and see if tab is in the correct spot that could be done with a second multimeter using continuity check with a multimeter attaching it to ground and the ignition wire to see if it in fact does not have continuity when points break for each respective cylinder when that piston is on bottom stroke=no continuity on plug wire when points break. If their is continuity when points break that would be a double fire for engine and the bakelite and tab are off to much resulting in double fire and a engine running erratically.

(You might have to attach multimeter wire to both spark plug wires to establish continuity which will still break when tab makes contact with one of them which would work also if attaching multi meter to one plug wire and ground doesn’t give you continuity. I read somewhere you test for continuity with coils with 2 ignition wires from plug wire to plug wire.)

The way I see this engine working correctly is continuity to the 1 plug wire is broken before the points break for each respective cylinder. If you get lucky and have continuity between the 2 plug wires that will make it a little easier to test (otherwise you would have to switch the multimeter to the other plug wire to and ground to test). As you rotate the flywheel continuity between plug wires should break for each cylinder before the points break. The continuity between the secondaries should also stay broken till the points break.

Hope that helps,
Joe

ps I think you said you have a buzz box you could also use that to see when points break.

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