JD 4010 switching to negitive ground

I have a 1963 John Deere 4010 gasser. Im going to switch it over from positive ground to negative ground. I have done this to 3 other tractors but it has been a few years. I will be using a Delco one wire alternator. I know the wire with the diode gets fed from a wire only hot with the switch and the other lug goes to the positive battery post. and of coarse switch the battery cables around. Any other hidden secrets I should know about before I do this? Thanks in advance

Since you are doing it a better way and using a diode feed from the ignition switch, you do not need to pay extra for a "one-wire" alternator.

<img src = "http://www.ndtel.com/~blweltin/Bob/AlternatorHarness4.jpg">

Just get an alt for a mid-80"s Chevy pickup without AC.

Since this is a gasser, switch the connections at the coil primary terminals, power from ignition switch to (+), (-) terminal to distributor/breaker points and condenser.

There MAY be an issue with the fuel gauge not being accurate after the polarity switch. If that is a problem/concern, the part numbers for an alternate gauge and sender that work on (-) ground can be found in the archives at the John Deere Board.

I'm assuming you're using a standard Delco 10SI
alternator.

If so, the wiring you described is correct. But a
true "one wire" alternator is just what it says,
only one wire that goes to the battery.

The standard 10SI has it's advantages if you don't
mind doing a little wiring.

Another method of wiring the output lead from the
alternator is to tie into the battery wire that
came off the regulator. That way the ampmeter will
still read a charge.

The only other change is to reverse the primary
leads on the ignition coil.

The JD4010 charge indicator is a light in the dash.
No sense losing that indicator as well as it being an excellent way to excite the 10si alternator at lower speed.
Find the small wire in your original regulator harness. it should connect with a larger wire that goes from the generator A or ARM stud to the regulators A ARM or GEN terminal. Connect this small wire to the alternators #1 excite terminal.

When you first turn the ign on, the gen light will ground through the alternator #1 terminal and light up. The small current from the gen light will excite the alternator at less than 1500 rpm. Once the alternator starts to charge, the gen light will go out as the #1 alt terminal goes from ground to +12V, so the gen light goes out. Also the gen light works as a current limiter so alternator back feed does not power the ignition system and prevent engine shut down, so no need for a diode or resistor.

Connect the alt #2 sense wire to the alt bat stud along with the heavy Bat wire from the original regulator.

If you already have the 1 wire alternator, just wire it up as instructed using a Delco alternator harness repair plug from your auto parts store for a professional looking and safe wiring job.

A Delco 1 wire will work just fine as a 3 wire alternator and the wiring is all in place for if you ever have to replace the alternator with a standard 3 wire model. Also as you say, reconnect the battery for neg ground.

I agree with the others, use a 3 wire alternator and you can have the dash light work.

Thanks a lot guys. Im glad I asked because I totally forgot about switching the wires on the coil! Thanks again

You say ONE WIRE ALTERNATOR so taking you at your word there's no messing with the excitation circuit wiring like if you used a 10SI three wire alternator. Its big main output stud (the one wire) that gets to the hot ungrounded battery post to charge it.

Swap battery connection to Neg ground:

Swap coil wires so + gets voltage from IGN switch while - wires to distributor:

No ammeter to have to swap leads unless one was added:

If the fuel gauge is a bimetal heating strip type its not polarity sensitive while if its a galvo type there may be some polarity issues??

John T

Will the fuel gauge still work if the polarity is switched on a gas tractor, or does that have to be rewired /replaced? That may have only been on 24 volt diesels that were changed to 12 volts.

It may not be something you want to consider but the 10SI one wire alternator can also be configured as 12V positive ground.