This one is NOT wired that way. The resistor is in line with the coil
all the time. The tractor is a Farmall Super M. I just replaced all the
low voltage wires because the old ones were cracking (dry insulation).
Anyhow, it goes from battery to a simple two terminal ignition switch
(push pull type). On to the resistor and to the coil/points. Thats it...
I just replaced everything in the ignition system except the switch. New
low voltage wiring, the resistor, coil, points/condensor, plugs and plug
wires. The stock coil that I bought says "For 6 or 12 volt systems".
"Resistor must be used on 12 volt systems". These tractors were
originally 6 volt. Most are converted to 12 (including mine) these days.
I assume these stock coils are 6v but work on 12v with the ballast
resistor. Without it, I would think the coil would be damaged. But I
like the idea of full voltage at starting. So I may try it. I'd just
need to run another wire from the push type starter switch to the coil.
I may give that a try. (the starter switch is a separate switch from the
ign switch. It's a push buttom spring loaded contacter).
I also have to add a light to the "dash" to remind me the ignition
switch is on. I know that I am supposed to turn off the ignition when
the tractor is off, but if I run out of gas, by the time I get more gas,
the battery is drained because I never remember to shut off that darn
switch. And I imagine that is hard on the coil and points. Possibly why
the old coil was weak and the old resistor was not allowing enough
voltage to the coil.
After changing all these ign parts, it really runs better, but now I
have to rebuild the carburetor. That thing tends to get flakey every so
often. But the tractor is over 60 years old, so it was due for all new
ignition parts, and a carb rebuild. Plus new fan belts are in order
next. They look bad....