I've heard you could run 12 volts straight to the pertronix. And the Flamethrower coils still have 2 versions, one with internal resistor and one to be used with external resistor.
Yes you can run 12 V to power the Pertronix. If needed, the resistor goes to the (+) side of the coil to limit the current that flows through the coil and, in turn, through the black lead of the Pertronix that connects to the (-) side of the coil. The Pertronix gets it's ground connection through the distributor plate. The following instructions are a little different from the instructions I got with my Pertronix, which just said to measure that the coil has at least 1.5 ohms resistance on the primary winding. From the Pertronix web site: What type of coil can I use with the Ignitor™? How do I check my coils resistance? (12V negative ground only) To determine if your systems coil is compatible with the Ignitor, some measurements should be taken prior to installation of the Ignitor. Caution… While performing this test, never leave the ignition switch on for more than 30 seconds at a time. Set your voltmeter to a 15 or 20-volt scale. Attach an 18 or 20 AWG jumper wire from the negative coil terminal to an engine ground. Attach positive (red) lead of your voltmeter to the positive side of the coil, and the negative (black) lead to an engine ground. Turn the ignition switch to the run position. Now read the voltage at the positive coil terminal. Turn the ignition switch off. If the voltage measured is approximately 12 volts, no resistance wire is present. A typical resistance wire will provide 9 - 6 volts. The next step is to determine the resistance in the primary ignition. Label the wires attached to the coil terminals and note their appropriate location. Make sure that the ignition switch is off and disconnect all wires from the coil. Adjust your meter to the lowest ohm scale. If you are using an analog style meter make sure to zero the needle. Measure from the negative terminal to the positive terminal. Write your measurement down. Now the maximum system amperage can be determined, divide your voltage measurement by your coil resistance measurement. This will give you the system current or amperage. Four and six cylinder engines should not exceed 4 amps. Eight cylinder engines should not exceed 8 amps. If the total amperage in your system is higher than the amount recommended for your application, you should install a ballast resistor. Example Voltage 12 Resistance 1.5 12 / 1.5 = 8 Total amperage 8
I see now. We are worried about too many amps getting to the Pertronix than the volts. So on a stock maverick wiring the wire to the coil should already have resistor inline, down to what 9 volts or so? So the coil used would be for an external resistor and lower resistance. I have the pertronix on my 70 F-100. Which i believe has no resistor in the wire and has an internal resistor in the coil. So if the resistance in my coil goes below 1.5 I should get a new coil to keep from getting too many amps and burning up the pertronix. When I put the pertronix on my truck 10 years ago I didnt see anything about that kind of test. I am using stock wiring and stock type coil and has worked fine.
