I have a like new MSD 6 that gives you a hot spark ... bought it for my
B3000 but found out my truck has " direct ignition " with no rotor so it
isn't compatable
wrote in message
oups.com...
Take out the resistor. It will run fine. One caveat. Make sure that
you do not leave the key on without the engine running. It WILL blow
up the coil. Running the higher voltage will give you a "hotter"
spark.

My dad, grand dad and I have been putting alternators on IH B and C
tractors for years. Of course all were originally 6V systems. We have
just switched them directly over to 12V using the original coil. As
long as you do not let the coil "soak" at this higher voltage it will
not adversely affect it. I am sure it does reduce the life of the
coil, but we have run then for an awful long time with out replacing
any of them. It isn't actually the voltage that is hard on it, but the
higher current that the primary windings take without the resistor
limiting the current.

As mentioned, this will result in a hotter spark. This is good. You
can run a wider gap and/or get the plugs to jump better if you are
burning oil or have likewise poor conditions.

As one other poster mentioned, you could put another resistor in
parallel to effectively 1/2(assuming matching resistor) your resistance
and bump up the primary voltage. This will work well and limit the
potential to cook the coil.

JW