Actually, the ballast resistor is wired to generate LOWER voltage for a running engine, and full power for starting. It's in series with the coil power wire so that the voltage drop across the resistor is about 6 volts, leaving only 6 volts for the coil. It's power side comes from the "run" position on the ignition switch. The "start" position has a wire directly to the coil so that starting is at full voltage.
This has the effect of reducing arcing across the points to extend their lifetime, but it also cuts the spark voltage.
Replacing the points in the distributor with one of the electronic or optical triggers means you can do away with the ballast resistor altogether. Also, I ran a race car with no ballast for years with a Bosch points set-up - wear of the points was the least of my problems, and fewer wires made for better reliability.
If you are going to use a HP coil, you are defeating your purpose to keep the ballast resistor at all.
One of the multi-spark ignitions with a no-points trigger will do very well. Use solid copper wire for the ignition wires ( though the fancy specs of high temp silicone covers does not matter for alfa 4's - the wires are no where near the exhaust manifold). Copper ignition wires do not break internally with repeated removal like the carbon-core or magna core wires do. They do leave pretty large EMI pulses which screws up your radio - but mostly in AM bands.
Besides, with the top down, who cares what's on the radio. Or you could get those fancy and costly Bosch wires that have resistors built into the plug connectors and metal shields over the plugs themselves....
Robert
This has the effect of reducing arcing across the points to extend their lifetime, but it also cuts the spark voltage.
Replacing the points in the distributor with one of the electronic or optical triggers means you can do away with the ballast resistor altogether. Also, I ran a race car with no ballast for years with a Bosch points set-up - wear of the points was the least of my problems, and fewer wires made for better reliability.
If you are going to use a HP coil, you are defeating your purpose to keep the ballast resistor at all.
One of the multi-spark ignitions with a no-points trigger will do very well. Use solid copper wire for the ignition wires ( though the fancy specs of high temp silicone covers does not matter for alfa 4's - the wires are no where near the exhaust manifold). Copper ignition wires do not break internally with repeated removal like the carbon-core or magna core wires do. They do leave pretty large EMI pulses which screws up your radio - but mostly in AM bands.
Besides, with the top down, who cares what's on the radio. Or you could get those fancy and costly Bosch wires that have resistors built into the plug connectors and metal shields over the plugs themselves....
Robert