4020 positive ground

[Anonymous-0]

hello jd wizards--i bought a 64 4020g the
guy couldnt get it to run rite he had the batt. hooked up neg. ground. im ready to start workin on it. did he do any damage to the starter or
coil? how do i check polarity of a component?
and how do i reverse polarity? thanks

 

[Anonymous-0]

A 1964 4020 GAS was originally a 12 volt POSITIVE ground system. If tractor has been converted to an alternator from its original generator it would have been changed to a negative ground. If tractor has been converted to an alternator the ignition coil polarity would/should of also been reversed. If the tractor is Negative ground the negative terminal on the ignition coil goes to the distributor. If the tractor is Positive ground the Positive terminal on the ignition coil goes to the distributor. DW

 

[Anonymous-0]

The starter isn't affected by battery polarity. The coil isn't damaged by reversed polarity, but it may not produce as strong a spark when reversed.

The gas gauges sometimes work less well with reversed polarity.

It was shipped positive ground. If only the battery was changed (and the generator flashed after the change) it will work, but it would work better if the coil primary terminals were swapped so the plus terminal goes to the ignition switch instead of the points in the distributor.

There probably is a resistor on the coil primary too, either a resistive wire or in the ignition switch and that is shorted out by an auxiliary contact on the starter solenoid to improve ignition while starting.

The original generator is only 20 amps and when that works right it can take an hour to make up for a tough start.

My gas 4020 now has an alternator and an ammeter so I can tell how its doing and it takes only a few minutes to charge the battery back up after a start.

The coil primary terminals should be labeled. The battery posts are labeled. Nothing else cares much about polarity other than the radio if it has one.

Gerald J.

 

[Anonymous-0]

The coil terminal going to the distributor on any tractor should be the same as the ground used regardless whether if a positive or negative grounded battery.If the battery is positive grounded then the positive terminal on the coil should be connected to the distributor. And visa versa.

 

[Anonymous-0]

thanks guys--i am ready to take this on.

 

[Kstinger]

(quoted from post at 21:36:08 05/29/07) The coil terminal going to the distributor on any tractor should be the same as the ground used regardless whether if a positive or negative grounded battery.If the battery is positive grounded then the positive terminal on the coil should be connected to the distributor. And visa versa. <br>

I have a 4020LP with positive ground and a generator. Also has a positive ground petronix in distributor. What would I need to convert to an alternator and negative ground?

 

[jd2cylman]

I have a 4020LP with positive ground and a generator. Also has a positive ground petronix in distributor. What would I need to convert to an alternator and negative ground?

You'll need a new Pertronix set. They are polarity specific.