Magneto Question

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aball36
Posts: 25
Joined: Wed Jan 15, 2020 9:36 pm
Zip Code: 48609
Tractors Owned: 1949 Farmall Cub
1951 Farmall Cub

Re: Magneto Question

Postby aball36 » Sat May 16, 2020 7:50 am

As suspected, the reading was very small, but not zero (0.3 Ohms). See attached photo.

However the other two combinations in pictures 2 and 3 are still reading infinite resistance (open) and nowhere near the 10k ohms range.

I might just try an external coil as a temporary (cheap) trial to see if I can rule out a bad magneto coil. The further into this thing I get, the more uncertain I get.

Adam
Attachments
magneto10.JPG

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Glen
10+ Years
10+ Years
Posts: 5395
Joined: Mon Mar 19, 2012 7:33 pm
Zip Code: 00000
Tractors Owned: 1956 Farmall Cub with Fast Hitch, F-11 plow, Disc, Cultivator, Cub-22 mower
Circle of Safety: Y
Location: Wa.

Re: Magneto Question

Postby Glen » Sat May 16, 2020 5:14 pm

Hi,
They have said on here before to replace the points and condenser first, because they don't cost a lot, and have to be good anyway. Then use the Cub, if it doesn't work better, then replace the coil. :)

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MiCarl
501 Club
501 Club
Posts: 560
Joined: Sat Dec 16, 2017 8:28 am
Zip Code: 48154
Tractors Owned: 1944 Farmall H
1948 Farmall Cub
1994 Speedex 1631
Circle of Safety: Y
Location: Livonia, MI

Re: Magneto Question

Postby MiCarl » Sat May 16, 2020 6:05 pm

You can't just slap on an external coil. You need to provide it with switched battery power (the power for the magneto coil is generated in the coil) and connect it to the points. You'll also need to disconnect the tractor kill switch (or at least leave it in the on position). Then I'm not sure the points and condenser are the same as for the magneto, you might ruin them.

I wish my Cub was at the house. I'd get you readings from my almost new coil.

Follow Glen's suggestion. Put in new points and condenser to rule them out. If that doesn't solve the problem (and I don't think it will) replace the coil.
1944 Farmall H
1948 Farmall Cub
1994 Speedex 1631

User avatar
Glen
10+ Years
10+ Years
Posts: 5395
Joined: Mon Mar 19, 2012 7:33 pm
Zip Code: 00000
Tractors Owned: 1956 Farmall Cub with Fast Hitch, F-11 plow, Disc, Cultivator, Cub-22 mower
Circle of Safety: Y
Location: Wa.

Re: Magneto Question

Postby Glen » Sat May 16, 2020 6:25 pm

Hi,
Yes, the points and condenser are the same for a magneto, and a Battery Ignition unit.
Below is a listing at TM Tractor for them.

http://www.tmtractor.com/new/el/367fp.htm

Below is a listing for a new magneto coil. :)

http://www.tmtractor.com/new/el/713fp.htm

aball36
Posts: 25
Joined: Wed Jan 15, 2020 9:36 pm
Zip Code: 48609
Tractors Owned: 1949 Farmall Cub
1951 Farmall Cub

Re: Magneto Question

Postby aball36 » Sat May 16, 2020 8:03 pm

Final update.

Hi guys, thanks for all of the useful advice. Low and behold, I reached out to tnestell who lives about 1.5 miles from me and he indicated that he had a spare magneto coil that he had taken off his cub 40 years ago and hasn't used since. I took a 5 minute ride over there and compared the readings on his coil to the coil that I had. The readings for his were right on the mark with what this group was saying (See attached photos). I installed it this evening, watched the static timing YouTube video that this group references frequently, made those adjustments and it fired right up. (I also replaced points and condensor while I was in there, but I am blaming the original malfunction on the bad coil:)

Again, thanks for the help and time this group puts in to giving advise.

Adam
Attachments
magneto13.JPG
magneto12.JPG
magneto11.JPG

User avatar
MiCarl
501 Club
501 Club
Posts: 560
Joined: Sat Dec 16, 2017 8:28 am
Zip Code: 48154
Tractors Owned: 1944 Farmall H
1948 Farmall Cub
1994 Speedex 1631
Circle of Safety: Y
Location: Livonia, MI

Re: Magneto Question

Postby MiCarl » Sat May 16, 2020 8:45 pm

Thanks for posting the numbers! Next time we won't have to guess.
1944 Farmall H
1948 Farmall Cub
1994 Speedex 1631


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