Need some help guys, on a Pertronix ignitor ignition my power supply is the resistance wire (white w/ orange bands) suppling power to the positive side of the coil. Will this wire give me the full 12 volts to power the ignition system?

Need some help guys, on a Pertronix ignitor ignition my power supply is the resistance wire (white w/ orange bands) suppling power to the positive side of the coil. Will this wire give me the full 12 volts to power the ignition system?
NO the "resistance wire" is there to drop the voltage to a set of points so they last longer. if you are NOT running points bypass the resistance wire for full ign voltage!

Easiest thing is to cut it 4-6" from the bulkhead connector and solder on a sufficient length of 12 guage stranded wire. Would be a good excuse to pick up a roll of harness tape, clean up any other loose ends or bad splices, and rewrap the engine harness. You'll like how it looks so much you'll want to do the lighting harness too!

Don't remember 100% but you got me thinking... when I upgraded my points to crane electronic retrofit and new coil, I was told to use the existing power supply by guy that rebuilt distributor for me. I would think this would be the same. Please confirm. If not why does it work?

Don't remember 100% but you got me thinking... when I upgraded my points to crane electronic retrofit and new coil, I was told to use the existing power supply by guy that rebuilt distributor for me. I would think this would be the same. Please confirm. If not why does it work?
oponions are just that= one persons view point, but the issue is will it get full voltage? the answer is no,yes it may work just not as well as it was designed to! you can breath with one nostril plugged but is that how you want to run the 440

It IS always important to read the directions.

Some electronic ignitions, such as mallory unilite, are designed to run with lower than 12 volts. Some will work with the resister wire, other require a balast resister and solis wire.

Some, such as a GM HEI, msd, or Accell billetproof, require the full 12 volts.

Others, such as pertronix or crane, I've never done so I don't know.

Most electronic devices are "tolerant" of out of spec voltage, but just because they function doesn't mean it's optimum.

Nearly all the manufacturers have instruction manuals available on-line if your is gone.

Read the directions!

I pulled the negative wire off the coil and grounded it, than turned on the key and read voltage on the positive side of the coil where the resistance wire connects and read 12.10 volts. I guess its getting what it needs to operate correctly. The yellow wire from the starter and the red from the distributor also connect at the positve side of the coil. Is this the correct way to check the output of the resistance wire?

I pulled the negative wire off the coil and grounded it, than turned on the key and read voltage on the positive side of the coil where the resistance wire connects and read 12.10 volts. I guess its getting what it needs to operate correctly. The yellow wire from the starter and the red from the distributor also connect at the positve side of the coil. Is this the correct way to check the output of the resistance wire?
NO- you can not run a voltage drop test unless the circuit is operating! start the engine and let it run- measure voltage from coil+ to bat - /now you will see what voltage is available to the coil

Easiest thing is to cut it 4-6" from the bulkhead connector and solder on a sufficient length of 12 guage stranded wire. Would be a good excuse to pick up a roll of harness tape, clean up any other loose ends or bad splices, and rewrap the engine harness. You'll like how it looks so much you'll want to do the lighting harness too!


Jim the first time i read thru i this i agreed and wasnt going to post but, then after i read some other post realized that the petronics kit wants 12v to the pickup
but I dont think you should put the full 12v to the coil because most coils are made for like 8v or whatever it sees after the ballast resistor

or I could be totally wrong, i just wanted to put this out here

Jim the first time i read thru i this i agreed and wasnt going to post but, then after i read some other post realized that the petronics kit wants 12v to the pickup
but I dont think you should put the full 12v to the coil because most coils are made for like 8v or whatever it sees after the ballast resistor

That's correct - the Pertronix module wants a full 12 volts to operate properly. The coil wants the reduced voltage from the resistance wire (or ballast resistor) unless the coil manufacturer says specifically that the coil is designed to run at a full 12 volts (all OEM coils are designed to run at 7-8 volts). :thumbsup:

That's correct - the Pertronix module wants a full 12 volts to operate properly. The coil wants the reduced voltage from the resistance wire (or ballast resistor) unless the coil manufacturer says specifically that the coil is designed to run at a full 12 volts (all OEM coils are designed to run at 7-8 volts). :thumbsup:
Always be carefull with the word ALL - most GM factory coils (hei and up) run at full voltage it is easy to engineer the amp load in the coil with the design of the coil itself why add another component in the wiring harness? remember we are switching the coil electronicaly now no points!

Always be carefull with the word ALL - most GM factory coils (hei and up) run at full voltage it is easy to engineer the amp load in the coil with the design of the coil itself why add another component in the wiring harness? remember we are switching the coil electronicaly now no points!

I was referring to point distributors, as the original poster was - HEI's don't need a Pertronix conversion. OEM point ignitions all use separate coils, and ALL OEM point ignition coils require either a ballast resistor or a resistance wire. :thumbsup:

In the Pertronix installation booklet, it states that '' A resistor wire or ballast resistor may or may not be included in the original equipment. They are not to be changed in any way with the installation of an ignitor system". The question is.....does that include a modern coil or are we talking an O.E. coils with low resistance? I am running an Accel Coil with greater than 1.5 ohms which is the minimum requirement for the ignitor. Also, do the aftermarket engine harnesses include the resistor wire going to the positive side of the coil or is the white with orange banded wire insulation there just for appearances only?

Dave, follow the directions. It might also be worth a call to Pertronix regarding compatibility (for sure) with that coil, although your statement that the directions say min coil resistance 1.5 ohms tells me it's ok as long as it's that or more.

Like a set of points, the electronic module works by "completing" or "breaking" the primary ignition circuit through the coil. When the circuit is "complete" current flows thru the primary side of the coil, then thru the module, to ground. The "amount" of current is dependant on the overall resistance of the primary circuit, which includes the resister wire or ballast, the primary side of the coil (3.2 ohms "stock", 1.6 "HiPo" [a 1.6 ohm coil will draw twice as much current, and deliver twice as much spark energy]) and the module itself.

An electronic ignition module also requires a power supply. This power supply is NOT part of the primary circuit, it simply provides power to the "switch" and sensor. Some require the power supply to be a full 12 volts, others (like the pertronix, judging by your excerpt from the directions) operate just fine with less.

Another member was recently PM'ing me about a Crane electronic conversion. That one required the module power supply to be a full 12 volts, BUT also required a resistance in the primary circuit!

Called Pertronix today, was told that their coil (Flame Thrower) needs 12volts to work properly so no resistance wire. If it's an OEM coil use the resistance wire and if you are using an later model coil it probably will need the full 12 volts.