Farmall Cub

Alright team cub spent the afternoon troubleshooting the electrical system On the backhoe cub - have no spark at all. Power to the starter but nothing to the plugs. I've attached a pic of something I have never seen before it's not on my 48 nor was it on my 51 or 55? Is not in my parts manual and not on any on line unless I've just missed it.

Thanks kt

External resistor for the coil

I know this is going to sound dumb but my electrical knowledge is limited. Why is it there? Is it necessary?

Yup. Ballast or external resistor to the coil. Drops the voltage across the points to between 6 and 9 volts. Used when converting a 6 volt electrical system to 12 volts.

They do malfunction. Continuity check across both terminals. Continuity - usually good. No continuity - no good.

I don't have a lot of experience with 12V conversions -- why would there be 2 ballast resistors on that system?
Roger

Mine did the same yesterday after I finished changing the oil & oil filter. Got to checking wires &to one was pulled off of the same thing you're showing in the pic. Plugged it back up & she fired right up. I didn't have any idea what it was either, but mine is mounted to the back of the alternator. Thanks for the post. At least now I know what it is, even though I knew I had to have it hooked up to run. Hopefully this simple fix will get yours going also.

If you have two maybe one is for 6V lights.

kxt710 wrote:I know this is going to sound dumb but my electrical knowledge is limited. Why is it there? Is it necessary?

The points ignition systems are typically designed to operate in the 6 to 9 volt range - - even on 12 volt trucks and automobiles. To reduce the voltage across the points you can either use a 6 volt coil and the resistor (resistor is less expensive than next alternative) or purchase a 12 volt coil with internal resistor.

So if I reading correctly I could get a 12 volt coil and remove the external resistors? Just a question in case I find the coil bad - it got pretty hot when I was trying to crank it today..

Kevin, You are correct just make sure the 12 volt coil has an internal resistor, as Eugene said.
Bill

kxt710 wrote:So if I reading correctly I could get a 12 volt coil and remove the external resistors? Just a question in case I find the coil bad - it got pretty hot when I was trying to crank it today..

12 volt coil with internal resistor.
NAPA part # IC14SB

It's not well documented in the parts manual, or anywhere I looked. But definitely should be on a 12v Cub, otherwise the coil gets wicked hot..... It will run without it (for a pretty long period too). I put an internal resistor coil on my 65 Lo Boy, the original coil was the same as a 6v Cub.

Are we looking at two separate resistors in the photo?

thiggy wrote:Are we looking at two separate resistors in the photo?

Yes, two resistors. One on top is wired to the ignition coil. Bottom one is probably wired into the lighting circuit.

Search for car voltage reducer 12 V to 6 V. There are several different styles still available.

We frequently used voltage reducers when upgrading older vehicles or installing inexpensive, readily available 6 volt appliances on 12 volt vehicles. Last one was when brother up graded his 1953 Chev truck, used as a business advertisement. Wanted to maintain the original gauges and windshield wipers.

Eugene, did his '53 Chevy truck have electric wipers? Mine had a vacuum motor. I put on a dual action fuel pump which regulated the vacuum. They worked as good as electrics as long as the motor was running. No more too slow or too fast wipers! I did have a '53 Bel-Air hardtop that I put a '57 electric motor in, and ran it and a tape player off a 12V battery in the trunk, rest of car was still 6V.