the truth is a high percentage of our cars work just fine with the resistance wire and thus avoid having to deal with running a new wire from switched ignition to the coil.
some cars have the resistance wire with such high resistance that the pertronix or any other ignition system has a problem.
If you have a tach car running a 12 volt bypass is a problem because then your tach no longer works.
the resistance wire was designed to drop the voltage to the points so you didn't fry them or fried them slower.
you can run a voltmeter on the coil wire and see what you have with the engine running or ignition switch to run, with the coil disconnected. many times you find your running well over 8 volts anyway even with the resistance wire.
but even lower then 12 volts the pertronixs runs fine. all it is doing and sensing the magnetic ring on the distributor under the rotor and triggering a hall sensor, that opens a transistor and triggers the coil the voltage that the coil originally saw with the resistance wire is still getting where it needs to be. also pretty much everyone is stuck using a high voltage coil today. you cannot even find an original spec coil without a massive undertaking. so even if your a little undervolt on the primary the secondary is putting out much more then it did when the car was new.
i think the myth is people think a computer CPU is inside the pertronixs, its really just a simple trigger that would work off 5 volts, the PII has a heat activated resistor that changes how fast the trigger goes off the effect is the dwell changes as the car warms up, this is suppose to help with start ups when the engine is cold. the solid state electronics are good from 5 to well over 20 volts.
the problems are when the resistance is REALLY high and under load your dropping well below 8 volts, or the electrical system is very heavily corroded and you have bad contacts and rusted grounds all over the place. then you need to run a bypass wire.
the best 2 places for a bypass are the STAT port on the alternator(which they warn you not to use, yet it works fine and ford used to wire electronic ignitions to it in the late 70s and 80s anyway) or you tap into the red green ignition wire at the switch in the column before the resistance wire.
either way you lose the OEM tach with this method, many guys do the bypass wire on idiot light cars since they have no tach.
I've tried it both ways on my car, my car ran better without the bypass wire, i also got less radio interference with stock ignition verse a bypass.
i believe the one time i checked my ignition wire voltage it was around 10 volts( but its been like 8 years since i did it)
