Is the Pink resistance wire needed?

[Larry G]

I'm rewiring my 70 Mustang with a painless wiring harness and would like to know if this wire is needed?

What does the Pink wire do? I know the pink wire has been discussed previously, but is it needed in a new harness?

 

[Midlife]

The resistor wire drops the voltage to the coil and the distributor points. The old-style mechanical points burn up much quicker with full 12V than the designed 9V.

 

[Larry G]

Thanks Midlife,
So the answer is no, I don't need the pink wire with the new harness.
I'm using the PreTronix module in the dist..

 

[Midlife]

Correctamundo!

 

[johnpro]

Correctamundo!

:wstup

If you don't have points, you don't need the resistor wire. The Pertronix will run at least 8v, so it's actually better, if you can, to get rid of the resistor wire once you remove the points. I know of no electronic ignition system that requires the resistor wire, either.

 

[Starfury]

Not entirely true. One of my friends and I discovered that you can't run 12V and a low-resistance (high performance) coil with the original Pertronix Ignitor. We discovered this after burning up his Igniter, my spare, and a shop's spare. Fun times.

 

[johnpro]

Not entirely true. One of my friends and I discovered that you can't run 12V and a low-resistance (high performance) coil with the original Pertronix Ignitor. We discovered this after burning up his Igniter, my spare, and a shop's spare. Fun times.

Yup, been there done that, myself. Has nothing to do with the resistor wire, though. If you're going to run an Ignitor with a low resistance coil, you need to run a ballast resistor between the two. Without the ballast resistor between the coil and the distributor, you'll still fry the Ignitor even with the resistor wire.

 

[68bucks]

Hmm...
When I first started driving my car I had a Mallory Dual point Distributor, I checked the Resistor wire, and although it started out at around 8 volts it would slowly climb to 12+ volts, so I placed a ballast resistor on the firewall and know holds it around 8 volts... I since have converted the Mallory to a Unilite electronic ignition and was told that I should leave the Ballast resistor to keep from spiking the bulb.. Is this not true? What would be the benefit of taking the Ballast resistor off?
The engine runs fine, but if removing the resistor would better tune it with out worry of spiking the bulb, I'm on it.

Dave.

 

[johnpro]

Hmm...
When I first started driving my car I had a Mallory Dual point Distributor, I checked the Resistor wire, and although it started out at around 8 volts it would slowly climb to 12+ volts, so I placed a ballast resistor on the firewall and know holds it around 8 volts... I since have converted the Mallory to a Unilite electronic ignition and was told that I should leave the Ballast resistor to keep from spiking the bulb.. Is this not true? What would be the benefit of taking the Ballast resistor off?
The engine runs fine, but if removing the resistor would better tune it with out worry of spiking the bulb, I'm on it.

Dave.

I'm no expert with the Unilite, but my thought is, if it ain't broke, it don't need fixin'.

It probably makes no difference, though. Doesn't one wire of the Unilite go to a full 12v source already? That's what's supplying the voltage to be stepped up by the coil. The resistor wire just becomes a signal to the distributor and it's "box" that the engine is on. That usually only takes abut 7-8 volts to accomplish.

I'd leave well enough alone, though. You will see no significant gain by removing the resistor wire.

 

[Starfury]

The advantage to removing the resistor wire is to increase voltage to the primary side of a high performance coil designed to run on 12V. If the coil isn't designed to run on 12V, bad things may happen. But if it is and you jump from 8V to 12V input, your secondary voltage will increase and you'll be able to open up your spark plug gap.

Also, the Ignitor II and domr aftermarket electronic ignition systems (like my MSD Distributor) require 12V to function properly. Without a 12V source, spark timing may be erratic. Found that out the hard way.

 

[johnpro]

The advantage to removing the resistor wire is to increase voltage to the primary side of a high performance coil designed to run on 12V. If the coil isn't designed to run on 12V, bad things may happen. But if it is and you jump from 8V to 12V input, your secondary voltage will increase and you'll be able to open up your spark plug gap.

Also, the Ignitor II and domr aftermarket electronic ignition systems (like my MSD Distributor) require 12V to function properly. Without a 12V source, spark timing may be erratic. Found that out the hard way.

I don't know that I would agree with that. I'm not sure which MSD distributor you're running, and/or if you're using an MSD6A or similar capacitive discharge unit with it. If you are, the MSD box is easily triggered via the resistor wire, and it MUST get it's power from the battery. So again, no need to remove the resistor wire. You can, but it doesn't benefit you AT ALL, at least for ignition purposes.

I have run MSD systems, and Pertronix I systems, both with and without the resistor wire, and all worked fine.

I would also not open up the spark plug gap unless you have a capacitive discharge unit like the MSD6A. All it will do is eat your plugs much faster. Now with the MSD6A-L in both my '69's 408, and my '66's 289, I run a plug gap of .050. The plugs still look brand new after a year of heavy running.

 

[68bucks]

I'm no expert with the Unilite, but my thought is, if it ain't broke, it don't need fixin'.

It probably makes no difference, though. Doesn't one wire of the Unilite go to a full 12v source already? That's what's supplying the voltage to be stepped up by the coil. The resistor wire just becomes a signal to the distributor and it's "box" that the engine is on. That usually only takes abut 7-8 volts to accomplish.

I'd leave well enough alone, though. You will see no significant gain by removing the resistor wire.

Well I dug out my instructions for the Unilite and remember why I wired it the way I did.
I have the ignition loom wire (the Unilite instructions are not calling it a Loom wire for auto applications) which has the Ballast resistor going to the + side of the coil and from there I run a red wire to the plug on the Distributor then a green wire from the - side to the Plug on the distributor and a brown wire from the plug to the block.

The instructions for auto installation tell me to splice a Ballast resistor into the ignition wire and connect it to the + side of the coil and then connect the red wire to the ignition switch side of the Ballast resistor then to the distributor rather than running it straight from the + side of the coil?

The instructions for marine application show it the way I have it wired, but the diagram shows a Loom wire without Ballast resistor.

The reason I followed the Marine application was because it showed a loom wire which my car has but isn't up to par, so I resisted it down.

So now looking back at the directions, I'm sure I did it right because its been that way for 3 years with out problems, so like you said don't fix it if isn't broken.

 

[Starfury]

John, I'm running the MSD Ready-to-Run distributor, no box. There was an erratic misfire I couldn't pin down until I supplied 12V to the coil/distributor. As soon as I jumped 12V to the + terminal, no more stumble.

The whole point of running a performance coil is to increase secondary voltage to allow you to open up the plug gap. Sure, if you're running a factory replacement coil .035" is about where you need to be, but when you double secondary voltage you should be able to open up the plugs to take advantage of that. I run my plugs at .045" with no problems. GM HEI systems, which run at ~100kV, are designed to run with a .050" gap.

 

[johnpro]

John, I'm running the MSD Ready-to-Run distributor, no box. There was an erratic misfire I couldn't pin down until I supplied 12V to the coil/distributor. As soon as I jumped 12V to the + terminal, no more stumble.

The whole point of running a performance coil is to increase secondary voltage to allow you to open up the plug gap.

Ok, I will buy that, and can understand it, with the Ready-to-Run and no auxiliary box. I could see where you want a full 12v to the + side of a high performance coil, and only supplying 7-8v to the distributor is only going to get you 7-8v to the + side.

With all the capacitive discharge units, you MUST have a full 12v to charge the capacitor, and the wire to it has to be able to carry quite a bit of current. This capacitor is what sends the voltage to the + side, and therefore will already be a full 12v, thus proving your point further.

In retrospect, the reason I always say not to open up your plug gap, just because you have a Pertronix Ignitor, may need to be revised. In my son's old '65, we had a Pertronix Ignitor and a Pertronix Flame Thrower coil, but it still had the resistor wire in it. As long as we gapped the plugs to .035", it would be fine for a long time. We tried twice to open up the plug gap a little (I think we went to .040") and the plugs would last about 2-3 months before the car would start running like crap. This whole discussion makes me wonder if removing the resistor wire would have let us run the wider gap.

Ok, Starfury, you have officially changed my mind and given me a lot to think about in this discussion, and for that, I thank you, sir! I do love an argument/conversation where someone can use sound logic and reason and convince me I may be wrong. Doesn't happen often, mind you, but every once in a while ...



So how about let's leave it like this ... if you run a stock style coil and/or points, leave the resistor wire in, and leave the gap alone. If you run a hi-performance coil and have no points, remove the resistor wire and open up the gap a little (or a lot) depending on your compression ratio and quality of ignition system and coil. Fair enough?