12 volt conversion

Z-man · Oct 1, 2014

installed my 12 volt conversion kit and did not have much luck getting the engine to start. I used the fena wiring diagram for a 10 si alternator and I had no spark at the coil, after switching around a few wire I then had the resister smoking I think something may be wire wrong. does the resister have a directional flow? would it be easier to just get a 12 volt coil. any help would be great maybe I just got a defective resister?

Z-man · Oct 1, 2014

is the ballast resister and the diode the same thing or they each have separate jobs, if I would go with a 12 volt coil would I need either if the two item to make the tractor charge and have ignition power?

Bruce(OR) · Oct 1, 2014

The ballast resistor is designed to drop voltage to the coil.
The diode is designed to allow current flow in one direction only.
It has been too long since I did mine and incorporated a few changes along the way beyond the standard rewire.
Total resistance in the circuit I believe was around 2.3 ohms and final voltage to the coil was around 8 volts. I ran a Ford starter solenoid activated by the Fergy starter botton. The quad post solenoid allows direct battery voltage to the coil while cranking. This in turn allows for a faster start. Once the engine is running, the voltage is routed through the ballast resistor.

2tractors · Oct 2, 2014

What 12v conversion would need a ballast anyway? That's for a 6v coil. If it smoked it probably opened.

Steve@Advance · Oct 2, 2014

The diode and resistor have completely different functions.

The diode goes in the wire between the ignition switch and the #1 terminal on the alternator. The white band goes toward the alternator.

The resistor goes between the ignition switch and the + terminal on the coil. It is not directional.

If you get the correct 12v coil you can eliminate the resistor. Ask for a coil with 3 ohms resistance.

Z-man · Oct 2, 2014

sorry, it was 6 volt I'm converting to 12 and what do you mean by open is it junk now

Z-man · Oct 2, 2014

do I still need the diode if I get the 12 volt coil or what is the reason for the diode

Z-man · Oct 2, 2014

do you have diagram or could you draw on and take a picture of it and post the picture for me to use on my tractor, see I have spark at the center coil wire the goes to the distributor but I'm not sure yet if it is going to the plugs.

Bruce(OR) · Oct 2, 2014

If you have spark at the coil wire then all you need to do is install it in the cap and pull off a plug wire. Crank the engine and look for a spark at the plug wire. You can also make a spark tester with a spark plug wire and a hose clamp.
Strip the wire off both ends, Secure the wire to the metal housing of the spark plug with the hose clamp. Secure the other end of the wire to ground. Connect the spark plug wire and crank the engine. The spark plug should fire if you have a good ground.

Steve@Advance · Oct 2, 2014

The diode is part of the charging system, it is necessary. The alternator requires an excitation current to get it started charging. The diode allows the current to flow to the alternator, but does not allow current to flow back back out. Without the diode the current would back flow through the ignition circuit and the engine would not shut off.

Z-man · Oct 3, 2014

I have a one wire alternator does it need a diode and were can I get one. could this be why do not have spark at the coil?

12 volt conversion

Z-man

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2tractors

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Steve@Advance

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