Reply to "Ballast Resistor"

The OEM wiring supplying power to the coil can be problematic in terms of supplying full voltage to the Duraspark coil. In some instances it was a resistance wire. In ALL cases its power passed through the ignition switch, which normally has very dirty contacts. Any bad connections will also create a voltage drop.

I recommend not using the OEM wiring to power the ignition, rather installing a relay to supply power directly from the battery. The wire which previously provided power to the coil (coil's + terminal) can be used to pull-in the relay. The relay then supplies power to the red wires (or red with green stripe) which power-up the positive terminal of the coil and the Duraspark module.

The wire which originally supplied the tachometer (coil's neg terminal) will need to be spliced into the green wire circuit (or green with light green stripe) between the coil negative terminal and the Duraspark module. Often the horse shoe shaped coil connector will have an additional "spare wire" attached to the same side of the connector as the green wire, specifically to provide for a coil connection.

I don't have a definite reply for you in terms of OEM wire colors, but I would guess the black wire with blue stripe is the tachometer wire. If you have a volt meter or "tester" you can verify this by turning the key to the run position, the tachometer wire will not supply power, the coil power wire will.