I'll probably get flamed for saying this butt....
I have been running my Pertronix II off the positive side of the coil with the resistance wire still in place for over 12 years with no problems.  Many will tell you that this is impossible, but I can only share my personal experience.

At one time I thought about bypassing the resistance wire, but I decided not to for 2 reasons.
1.  If it ain't broke don't fix it
2. If the Pertronix unit ever fails I can buy a set of points at a local auto part store and swap them in without having to worry about putting the resistance wire back in place first.
 

Michael H. wrote:

I'll probably get flamed for saying this butt....
I have been running my Pertronix II off the positive side of the coil with the resistance wire still in place for over 12 years with no problems.  Many will tell you that this is impossible, but I can only share my personal experience.

At one time I thought about bypassing the resistance wire, but I decided not to for 2 reasons.
1.  If it ain't broke don't fix it
2. If the Pertronix unit ever fails I can buy a set of points at a local auto part store and swap them in without having to worry about putting the resistance wire back in place first.
 

I have also used the resistor wire to power the Pertronix but had a bad miss at high rpm that took months to locate ...it was the resistor wire...always use a keyed 12 volt source....jj 

Last edited by jerseyjoe (6/25/2016 6:04 AM)

Robby 13 here. I also have a 67 with a pertronix 2. The pertronix is made to run direct 12 volts for best results. Red wire from pertronix to pos coil, to directly behind the ignition switch, green wire, red stripe. I disconnected the resistor wire and folded it back along the harness and taped it. You must also use the proper coil for which ever pertronix you have. The best way to make sure is to call pertronix tech line, I spoke to Marvin, he explained it best.

This is the thought I had that would avoid cutting any of the harness.

Run a direct 12 volt feed to a standard relay switch. Then use the brown wire "I" terminal post off the starter relay to act as the trigger to turn on the external relay switch and send 12 volts to the distributor.

The brown wire "I" terminal is fed directly from the ignition switch via the pink wire under the dash so it should be hot in start and run only. The lower voltage should be no problem in terms of just triggering the relay. I have used this same approach to deal with horns that are not getting enough juice to function.

Is there any flaw with my logic??

I actually ran mine through the resistor wire for a very long time with no problems.  I would just rather the system get 12V.

I don't think I'd want a relay in this circuit.  Not that it wouldn't work, but its a level of complexity, another thing to fail.  If you're already worried about what happens should the Ignitor fail, now you've also got to be worried about what happens if the relay fails?  More spares to carry, etc. 

TKOPerformance wrote:

I would never switch back to points.  If you're concerned about a failure just buy a second Pertronix and have it ready to go in the emergency kit.  That being said, a failure if the unit is installed right is about slim to none.

I bypassed the resistor wire and ran 12V directly to the coil and the Pertronix.  I had to run a tach sender wire too, so I simply ran a white and a red wire from the dash, through the firewall (small grommet below the existing gauge feed one), and loomed it in to the gauge feed harness.  I used some tricks like using Solder Seal terminals and them shrink wrapping with black shrink tube on top.  You would have to be looking for it and really know what you're looking at to see that anything isn't factory.

I'm trying to remember where I taped keyed 12V, and I'm thinking it was off the factory tach wiring, which unless you have that underdash harness probably doesn't do you any good.  Other options are the red wire going to to ammeter should be a keyed 12V, but you need to verify that whatever you use is hot in run as well as in crank.  Tapping directly off the ignition switch may be your best bet. 

 
The ammeter wire, while delivering the necessary 12 volts for your Ignitor, is shorted out, probably via the voltage regulator, while in the start or crank mode, and will not deliver voltage to the Ignitor during the cranking activity and will not allow the engine to start.
Best,
Al

LondonSteve wrote:

This is the thought I had that would avoid cutting any of the harness.

Run a direct 12 volt feed to a standard relay switch. Then use the brown wire "I" terminal post off the starter relay to act as the trigger to turn on the external relay switch and send 12 volts to the distributor.

The brown wire "I" terminal is fed directly from the ignition switch via the pink wire under the dash so it should be hot in start and run only. The lower voltage should be no problem in terms of just triggering the relay. I have used this same approach to deal with horns that are not getting enough juice to function.

Is there any flaw with my logic??

 I'm in agreement with TKO about keeping it simple and not using a relay but I thought I'd post options so you could decide what is best for you. The first pic should work with a 9 volt coil. It would supply 12 volts to the pentronix and 9 Volts to the coil.

The next Pic could be used with a 12 Volt coil. You would have to disconnect the Red/Green wire from the + side of the coil and connect them together.  

Last edited by wsinsle (6/25/2016 8:40 AM)

Why not unplug resistor wire under dash, run new wire from there to coil? Simple and works.
Howard

Why I always advise testing.  A voltmeter doesn't lie, but I'm human and therefore could be wrong once in a while.