Magneto question

37 chief · Jan 1, 2023

Back in the 30's Edision Splitdorf mags were used on tractors, and motorcycles. I have a four cylinder mag I want to install on my 36 Indian 4. Inside
the magneto at the points it says 30 degrees. what does this mean? Is this for timing a magneto with a impulse coupling, which I removed, and don't
need. Advance and retard is by a separate manual lever for starting. Thans, Stan

Janicholson · Jan 1, 2023

One possibility is Dwell. That is the degrees of rotation that the points are closed out of 360 degrees. Mag degrees, not engine. Jim

Geo-TH,In · Jan 1, 2023

Stan,
I might be wrong.
The impulse coupling is needed to get a hot spark during starting.
Your Indian is like the old hand crank tractor.
If I recall the old AC had one lever for the throttle and the other lever was for spark advance.

Post back if you can start the Indian without impulse coupling.

Dwell angle is the number of degrees in the ignition cycle during which the points are closed.

redforlife · Jan 2, 2023

Thinking you will have weak spark for starting without the impulse. Kick starting versus hand cranking, or electric start might make a difference, I dont know. Might turn things fast enough to not matter.

Not sure about splitdorf, but some impulses will dump the spark after TDC when they are tripped. If they are not working, you don't get the trip delay, and this will bring your spark delivery back to before TDC. You could set your actual timing to adjust for this, but then your timing would be set for starting and not run. You could probably account for this with your spark advance lever (if your using it), but your window of this adjustment might get smaller (meaning it might not advance enough to oppropriate run setting, if you got to retard it extra further for a starting mode without impulse use).

All depends on how the impulse is set up on that mag, whether it can be eliminated or not. If all the retarding for starting is done by the spark advance control, and no retarding done by the impulse itself, the spinning fast enough for starting would be the only issue with eliminating impulse.

Butch(OH) · Jan 2, 2023

I am not familiar with that particular magneto but whenever I have seen that on others it refers to the lag angle of the impulse coupling. The angle varied with the application as one does not want the impulse snapping before top dead center if he values his arm, or in your case your leg. Correctly installed it will provide 30 degrees of advance when set to trip at TDC. All can be worked with since you also have a manual adjustment. Id keep the impulse working if it were me as its a great aide to starting but they are usually easily defeated by removing the trip.

560Dennis · Jan 2, 2023

As mentioned 30 degrees advance on an impulse sounds right to me .
Some thing to chack are the impulse spring conditions.
There are a lot of good magneto people around to replace or sell parts look in magazines Minneapolis area,Illinois ,Ohio, New England
Ask for references

Magneto question

37 chief

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Janicholson

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Geo-TH,In

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redforlife

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Butch(OH)

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560Dennis

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