H Coil.........

Goose · Sep 18, 2019

In going over a recently acquired H, I found the wire to the distributor was connected to the + side of the coil, and the wire from the ignition switch was connected to the - side of the coil. I've always thought the wire from the ignition switch connected to the positive side of the coil.

Haven't looked at my two other H's yet, but my M has it the other way around.

Which is right? None of my manuals say anything about it.

old · Sep 18, 2019

When new an H was + ground so that would be correct if it is still uses the positive ground on the battery. But if switched to 12 volts and an alternator then it would be - ground so you should switch the coil over to a - ground which is the distributor side

Goose · Sep 18, 2019

Thanks for the info!

I'd really never seen or heard this addressed before.

old · Sep 18, 2019

I and John T have said things about this many times. One can always figure it this way. What ever the ground is on the tractor that is also the side of the coil that goes to the distributor or the spark will jump backwards

John T · Sep 18, 2019

Old has you well covered...?..If your two tractors are different and actually wired correct to match coil polarity to the tractors polarity, that may be because one is POS ground the other is NEG. Many older 6 volt were wired POS ground in which case + of coil wired to distributor, but many 12 volt or if converted to alternator and NEG ground has - of coil to distributor. They still fire at the incorrect polarity but its more efficient if wired correct. Its best to emit electrons off a hotter (plugs electrode tip) to a cooler (plugs ground strap) surface. That's how vacuum tubes had heaters under the - cathode and electrons flowed to the cooler + plate. Thermionic emission or something like that. Its possible to have the lead end of a lead pencil in the current path between plug wire to the plug to see the direction of current flow.

Nuff said

John T

Bob · Sep 18, 2019

Here's a link to a manual that DOES cover coil polarity.

You will need to copy each link and paste it into your browser's address bar, as it will not work as a direct link form here.

(From John Deere "FOS-20", "Fundamentals of Service, electrical systems".

http://farmallcub.com/rudi_cub/www.cleancomputes.com/Cub/Blue%20Ribbon%20Service%20Manuals/FOS-20%20Chapter%206-Ignition%20Circuits/Page-04.jpg

http://farmallcub.com/rudi_cub/www.cleancomputes.com/Cub/Blue%20Ribbon%20Service%20Manuals/FOS-20%20Chapter%206-Ignition%20Circuits/Page-05.jpg

Goose · Sep 18, 2019

Thanks!

Thinking on it, my M is converted to 12v.

H Coil.........

Goose

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old

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Goose

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old

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John T

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Bob

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Goose

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