Electrical question on 1947 8N

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Electrical question on 1947 8N

Postby zburton » Mon Apr 23, 2018 9:59 pm

Alright so I know this is technically not the correct brand of tractor but I figure its electrical and it would apply.

So the tractor has a 6v single wire alternator that is wired to the junction terminal then it went to the ignition switch and the amp meter the amp meeter goes to the starter solenoid and hooks on the same terminal as the negative bater cable. The ignition switch goes to a terminal that has the resistor but the previous owner did not keep the resistor in the circuit and hooked the coil strait to the ignition wire. Does that sound like it is right or not? it used to have a generator and voltage regulator but they took those out. It has positive ground.

Hopefully one of you could help me on this one, thanks in advanced.

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Re: Electrical question on 1947 8N

Postby RonT » Tue Apr 24, 2018 6:45 am

Are you certain the alternator is a 6V one?

Most folks would put 12V one wire alternator and change over to 12V negative ground to be compatible with the alternator.
If the electrical system is 6V, no ballast resistor is required in the primary ignition circuit.
If it is 12V, you either need a 12V coil that has an internal ballast resistor (it will say "no resister required"), or use the external resister in the circuit.

I hope this I helpful.


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Re: Electrical question on 1947 8N

Postby zburton » Tue Apr 24, 2018 10:10 am

The alternator has 6v stamped into it and the battery is still positive ground. Not sure why the previous owner didn’t switch it to 12v they were practically there when they did it. So with it set up the way it is it can be hooked directly to each component then? Without any resistors.

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Re: Electrical question on 1947 8N

Postby John *.?-!.* cub owner » Tue Apr 24, 2018 9:32 pm

If it is 6 volt, yes, not having the resister is correct. The resister is for dropping voltage from 12 volts to 6 for the coil when a 12 volt alternator is installed. 6 volt alternators are rare, and used to be quite expensive, in the area of $100 in the late 60s when I worked in an auto parts store while going to college. The reason we had them was the Missouri Pacific car shops were just across the street from us and some of their equipment used them. It took so long to get them through normal channels they would come and get them from us. We could have one in the store the next morning, it took them 2 to 6 weeks. They did not want to wait that long to get their own equipment for making repairs running.
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Re: Electrical question on 1947 8N

Postby Landreo » Thu Apr 26, 2018 7:42 am

A ballast resistor is for more than 12v to 6 volt systems. Some Fords used them in their 6 v systems to further reduce the voltage to the coil. I am not sure about all of the N series but if the tractor has the original coil then it should have a 0.8 ohm ballast resistor.

A ballast resistor is different from a regular resistor and, in this case, allows more current to the coil when starting.

Not all ballast resistors are the same resistance. Don't use that 0.8 ohm resistor for a 6v Ford in a 6 to 12 volt conversion and don't use a higher ohm resistor for a 6 to 12 volts conversion in a 6 volt Ford.

You can measure the resistance of your resistor, 0.8 ohms then put it back in, 2 ohms or so then leave it out.

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