Farmall 140 coil w/ built in risistor

RUN-N-LATE · Feb 10, 2015

Need a little help. If I go to NAPA store and get a 12v coil w/built in resistor I can do away with the external resistor and that all I will need. Would there be anything special I need to ask for on the coil or would that do it.......Thanks Mark

El Toro · Feb 10, 2015

Here's the part number for that coil and you don't need the resistor. Hal
IC14
PS: The wire from negative post on the coil goes to your points.

jsfarmall · Feb 10, 2015

That's right, no resistor. My Cub and H both have electronic ignition and no resistor. Coils are internally resisted.

RTR · Feb 10, 2015

(quoted from post at 17:30:12 02/10/15) Need a little help. If I go to NAPA store and get a 12v coil w/built in resistor I can do away with the external resistor and that all I will need. Would there be anything special I need to ask for on the coil or would that do it.......Thanks Mark

I think that the late model (mid-1976 to 1979) 140 tractors had a "resistor" come on them from the factory and it was bolted to the side of the alternator. It was the same type resistor used with the points and coil. Not sure if it went to that or the factory alternator, or both; but I thought I would just throw this info out there. If you have a 140 of this year range, make sure it isn't something you "need" to keep.

RUN-N-LATE · Feb 11, 2015

Thanks to everyone who replyed that part # was very helpful at NAPA stre.

Janicholson · Feb 11, 2015

12v coils with no external resistor needed do not have internal resistors, they have thinner wire for the windings, and more of them to run on 14.2 volts. It is logical to think that they do, but nope. Jim

Owen Aaland · Feb 11, 2015

(quoted from post at 18:40:10 02/10/15)

(quoted from post at 17:30:12 02/10/15) Need a little help. If I go to NAPA store and get a 12v coil w/built in resistor I can do away with the external resistor and that all I will need. Would there be anything special I need to ask for on the coil or would that do it.......Thanks Mark

Click to expand...

I think that the late model (mid-1976 to 1979) 140 tractors had a "resistor" come on them from the factory and it was bolted to the side of the alternator. It was the same type resistor used with the points and coil. Not sure if it went to that or the factory alternator, or both; but I thought I would just throw this info out there. If you have a 140 of this year range, make sure it isn't something you "need" to keep.

The resistor of the alternator of the mid-1976 to 1979 is part of the charging system, not the ignition system. It is a 25 ohm resistor. It is used with alternators with the internal regulators.

RUN-N-LATE · Feb 12, 2015

Thanks for all the help, any other litle tips would be apprecited, I am rewiring my 1962 farmall 140 that had been already converted but wires where cut off here and there and just trying to get everything back to standard,any tip that has not been post would be helpful.......Thanks Mark

mkirsch · Feb 12, 2015

A bit of tongue-in-cheek advice: Some people get pretty bent out of shape when you mention internal resistors and coils in the same sentence. I'd avoid that from here on out.

One reason manufacturers continued to use 6V coils with external resistors on 12V machines is so the coil could be boosted with a direct shot of 12V during starting to produce a nice hot spark for easier starting. This was accomplished with a bypass circuit that was powered by a special "S" post on the solenoid.

Farmall 140 coil w/ built in risistor

RUN-N-LATE

Member

El Toro

Well-known Member

jsfarmall

Member

RTR

Well-known Member

RUN-N-LATE

Member

Janicholson

Well-known Member

Owen Aaland

Well-known Member

RUN-N-LATE

Member

mkirsch

Well-known Member

Similar threads