Farmall C 12v Wiring Diagram

jvermast

Member
Hi Guys

Anyone happen to have this? I've been looking around all night trying to find one with an alternator and 12v conversion.
 
You don't need a "diagram". Get a GM one wire.About 55 bucks. Run one wire from the alternator's battery post to the amp gauge.Then run a wire from the gauge to the battery.I like to run it to the starter.Then run one wire from the amp gauge to the ignition switch,then back to the coil.. Done. Be sure to run a separate ground wire from the alt to the frame(I like to run it to a valve cover bolt).If you want lights,pull power from the amp gauge.Wrap the whole thing neatly in black tape. Easy,simple......Don't need to buy a 'kit',just doit yourself. BTW,you may need to build a bracket to allow the alt to fit cleanly under the hood.
 
Nope.Some guys say you need one on the points to keep them from burning. But I never had one,never had an issue.
 
"Do I need a ballast resistor in there anywhere?"

If you use the existing 6 volt coil, yes you need a resistor between switch and input to coil. It should be about 1 1/2 ohms to match resistance of the primary of the coil. Doubling the voltage from 6 to 12 volt battery doubles the current through the points and coil. A resistor equal to resistance of coil primary limits current to original level.

If you use a direct 12 volt "no external resistor required" coil, then no, you do not use a resistor. (NAPA IC14SB or equivalent).

With generator to alternator conversion you will need to change system from positive to negative ground. Reverse connections on ammeter and connect -- post on coil to side of distributor. Install battery negative to ground.

Starter should work on 12 volts and will turn same direction regardless of battery polarity. Change lights to 12 Volt
 
(quoted from post at 23:30:15 05/16/18) Nope.Some guys say you need one on the points to keep them from burning. But I never had one,never had an issue.
The resistor really isn't for the points, it's to reduce the current to the coil. The dwell or charge time of the coil is fine when 6 Volts is supplied to the coil, but with 12 Volts, the coil is being overcharged constantly. It won't kill the coil immediately, but it will definitely shorten it's life and you will notice that it is much warmer than it should be when you run a 6V coil on 12V without the resistor.

These engine are low RPM and only 4 cylinders, so they have considerable more charger time than a V8 at much higher RPMs, there is no added benefit to running the 6 Volt coil on 12 Volt, and it will just shorten it's life.
 
Would a battery like this be negative ground? How do I even know before buying? I believe I need negative ground for a 12v tractor?

https://www.napacanada.com/en/p/NAB26245U
 
(quoted from post at 07:35:21 05/22/18) 12V would be negative ground on these tractors.

So I just swap the wire from the starter and the ground?

12valt.jpg
 
It looks ok, other than your ammeter. The battery should be on one post and all the loads and alternator on the other post.
 
(quoted from post at 14:57:11 05/22/18) It looks ok, other than your ammeter. The battery should be on one post and all the loads and alternator on the other post.

10-4 will do. Makes sense!
 
Dorr the sake of safety, there should really be a fuse before every load on the battery, but many people just put one for the lights. One for the ignition would definitely not be a horrible ideas, just size it appropriately for the wire size and load.
 
The inability to edit gets me too, especially when typing replies on this "smart phone" and it for instance changes For to Dorr.
 

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