Hi Steve,
1. I don't see a need, as long as the wires are properly terminated & insulated.Easy to check: with the engine running, disconnect one. If nothing changes, put it back & disconnect the other.
(Viperwolf and Paul ... This addresses your posts, too.)
I was finally getting around to installing a MSD solid state coil today. I intended to install it several years ago, and just now see the benefit with the propane.
The initial setup was with the two wires from the resistor connection from the harness in the engine compartment and the wire from the ignition switch wire to one side of the resistor. The other side of the resistor was wired to the + side of the solid state coil. The motor cranked and started; but, after about 30 seconds the engine wouldn't run... it was missing and wouldn't idle.
I switched back to the conventional coil. The motor started and ran fine. (I may have the timing a little far advanced now; but, the motor idled pretty well.)
So... I went back and removed the two wires to the one side of the ballast resistor. I connected the wire from the ignition switch to the balast resistor, leaving the wire from the connection in the engine bay unconnected. The motor would not start. (It may be worth mentioning that the moment I turned the key from the start position to the normal running position, there was ignition for just a short time, although the motor didn't start.)
I then removed the wire from the ignition switch and connect the wire from the harness in the engine bay. The motor started and idled well.
I then switched coils with only the engine harness wire connected to the ballast resistor. The motor idled for about 10 minutes with no problem.
So, it appears that the conventional coil is tolerant of the way the ballast resistor was wired previousl; but, the solid state coil won't run with the wire from the ignition switch wired to it.
I don't know the reason why one of the previous owners would have wired both wires to the ballast resistor. I was doing my best to get under the dash and see which terminal on the ignition switch was wired to the ballast resistor; but, I couldn't tell. I think my only option if that's needed is to remove the switch. (Or, is there a switch assembly that can be removed from the switch so that the wiring can be looked at below the dash?)
Thanks for any thoughts.
Jeff