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How to tell polarity?

J

John 37A

Member
I have a late a that I'm trying to get running and am not sure of the polarity. There is a 12 volt sticker on the battery box, but no indication of + or - ground. There was no battery in it when I bought the tractor. I am going to order electronic ignition and would like to make it negative ground (if its not already).
 
If it has a coil that should tell you what it was
setup for...but if you're going to do the electronic
ignition then why bother. I'd recommend buying a new
coil with the ignition kit to ensure you've got a
good ignition system.
 
I got a new coil. I think to change polarity, I need to switch coil wires, among other things, but I'm not sure how to tell if they are already switched? + wire from the switch and - wire to the distributor.
 
If your tractor still has a generator don"t forget
to polarize it before you get ready to start the
tractor for the first time as negative ground.
 
Allllllllll two cylinder Deeres were originally Positive ground. Of course, you can change it to Neg now if you wish JUST BE SURE TO POLARIZE THE GENNY BEFORE START UP. If you change to Neg ground the coils + gets ign switched voltage while its - wires to the distributor (opposite as original) Also the ammeter leads need swapped or it would read bass ackwards.

John T
 
Thanks, John. That's exactly what I was looking for. My tractor has been switched to negative ground already then.
 
Coil polarity is simple. The points ground the coil primary momentarily, so whichever is your ground system, that"s the one you run to the distributor. Pos Grd = pos to dist, Neg grd = neg to dist
 
Hey John T! How ya doing? Let me see if I understand what you are saying about the coil. I"ve just bought a JD G that the previous owner added an alternator and switched to a negative ground. So he must have or should have switched the coil wires too? So when I put a generator on it, I should expect to switch the wire from the coil to the distributor.

Rav
 
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