Ford 860 - Positive or Negative Ground?

MikeyK

Member
Hello,
Prior to receiving my grandfather's 1955 Ford 860, my father had covered it to 12v. My dad is a great man but he isn't really a detail person and I know he had never done a 12v conversion before so I'm not sure it was/is wired 100% correctly.

When I got it, it appeared to be positive ground (+ terminal connected to the solenoid, - terminal connected to the frame). However, I replaced the original coil over the weekend and, after I removed it, I noticed the negative terminal on the coil was connected to the front post of the solenoid while the positive terminal was connected to the distributor.

After installing an electronic ignition (purchased the model for positive ground system) and a new coil, I connected it the opposite way because I thought the original way was wrong. The thing is, it started and ran connect the way I originally received it and it also runs now, with the coil reversed. I just don't know if it's all connected correctly so everything runs as efficiently as possible with no premature damage to the electrical system. Any thought? Thanks.

-Mike
 
With the - hook to the tractor frame that makes it - ground sine the frame is ground and having the + hooked to the start also say - ground since the system is working form the + side of the battery. If you where to hook up the battery the other way around good chance you would let the smoke out of the alternator the moment you hooked up the battery and could even cause the wiring to burn up
 
Hi old,
Thanks for the reply. So, the fact that the coil was connected backwards doesn't really matter?

What details, besides the positive battery terminal being attached to the frame and the negative terminal attached to the solenoid, make a tractor a have a "positive ground" electrical system? There must be other differences or people could easy "convert" from - to + ground by simply swapping the battery cables.

-Mike
 
Coil should also be hooked up + to the ignition and - to the distributor or it will not work as well but still work.
As for + or - ground most things do not care which is which but an alternator will care and it hooked up wrong will be burned out the moment you hook it up wrong. A generator on the other hand can be made to work either way but if it has a solid state V.R. it does care and like an alternator it will burn out
 
Always happy to help if and when I can. I even have people who e-mail me direct and or call me on the phone for help. I believe knowledge is something that should be shared or it will be lost forever
 
old,
I couldn't agree more. My tractor is over 62 years old and all of the current experts aren't going to be around forever. I've been doing my best to soak up as much information as possible in hopes of being close to as helpful as people like you.

-Mike
 
Would you believe I have never had any classes in mechanics and have learned what I know as to fixing engines etc. by the road of hard knocks. Now electronics I was an E.T. when in the navy and repaired computer while in so electrical stuff is no problem either
 
in the old days they didn't know much about electricity. Someone started with a positive ground with a 6v battery and that was 'good enough'
and everyone else followed along. Didn't take much to spin a starter for a 4 cylinder small engine......

After a while they figured out that a few parts could work a little bit better with a negative ground, and current flowing that way. But things were
already common 6v positive ground so no one changed.

Engines got bigger, lights got brighter, and rust started showing up in wire connections. They needed more power to run bigger starters, and
they were running into a lot of hot wires because 6v is so weak to jump through a poor connection.

So they switched to 12v systems. More power in the same wire size, and less troubles with poor wire connections. (Voltage is how much push
is in the system. If it were water, it would be the water pressure....)

As long as they were changing, they now went to the slightly better negative ground setup. And those new things, alternators almost always
were used now, but the alternator is a one-way thing, it cares a lot which direction you feed it!

Most of the 6v parts don't really care at all which way the current flows, just have to polarize the generator for the direction you want.

Most 12v systems use an alternator, and that alternator is built with parts that only work one way, so it matters a great deal on 12v systems. You
can easily harm the alternator by flowing the wrong way.

As time moves forward, there are more and more fussy electronic bits in the system that only flow one direction on 12v systems.

So nearly all 6v systems are postive ground.

And nearly all 12v systems are negative ground.

But - a few generators were made that put out 12v, (and a few old 6v can be re wired to 12v) and can run a 12v postive ground setup. So just in
case a person got one of those rare setups or conversions, it is difficult to universally say all one way or the other way.....

Paul
 
Hi paul,
Wow, that's pretty interesting, thanks for taking the time to explain. Hopefully this forum thread will help a lot of other people who have question about their tractor's electrical system.

-Mike
 

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