Mallory Unilite Stumper

[Michael Oritt]

I have been running a Mallory Unilite ignition system in my 100 coupled to a ceramic ballast resistor as recommended and an MSD coil for 15 or so years with no issues. The system was wired as per Mallory's instructions shown on the attached "Unilite--Original Wiring" file. The purpose of the ceramic ballast resistor is to reduce voltage to the ignition module from 12 to about 6 so as to protect it from overcurrent.

Recently I decided to replace some older wires and connectors with new and in the course of planning the reactivation of the ignition system I found a number of posts in different online sites--mostly for muscle car and other large V-8 applications--recommending the addition of a new wire from the ignition switch to the positive side of the coil. The purpose of it would be to temporarily increase voltage during starting.

I've never had any difficulty with starting and the car usually fires off almost immediately, Nevertheless I thought I'd give things a try and so yesterday I added the new wire from the start button to the coil positive. as shown in red on the second attachment "Unilite Revised". On pushing the start button the car started instantly, but died as soon as I released the button. This repeated several times and only after removing the new wire from the start button to the coil would the car run after starting.

I'm really okay taking "no" for an answer and have eliminated the problem simply by disconnecting the new lead to the coil positive, but I would like to understand why this is happening--It's as if the coil was being de-energized or somehow grounded out. The start button also energizes the built-in solenoid for the aftermarket gear reduction starter, but I don't see any way that could be the culprit.

Thoughts please?

 

[BobHaskell]

I have been running a Mallory Unilite ignition system in my 100 coupled to a ceramic ballast resistor as recommended and an MSD coil for 15 or so years with no issues. The system was wired as per Mallory's instructions shown on the attached "Unilite--Original Wiring" file. The purpose of the ceramic ballast resistor is to reduce voltage to the ignition module from 12 to about 6 so as to protect it from overcurrent.

Recently I decided to replace some older wires and connectors with new and in the course of planning the reactivation of the ignition system I found a number of posts in different online sites--mostly for muscle car and other large V-8 applications--recommending the addition of a new wire from the ignition switch to the positive side of the coil. The purpose of it would be to temporarily increase voltage during starting.

I've never had any difficulty with starting and the car usually fires off almost immediately, Nevertheless I thought I'd give things a try and so yesterday I added the new wire from the start button to the coil positive. as shown in red on the second attachment "Unilite Revised". On pushing the start button the car started instantly, but died as soon as I released the button. This repeated several times and only after removing the new wire from the start button to the coil would the car run after starting.

I'm really okay taking "no" for an answer and have eliminated the problem simply by disconnecting the new lead to the coil positive, but I would like to understand why this is happening--It's as if the coil was being de-energized or somehow grounded out. The start button also energizes the built-in solenoid for the aftermarket gear reduction starter, but I don't see any way that could be the culprit.

Thoughts please?

Does the new wire go to ground when you release the starter button?

 

[red57]

The 'revised' wiring you show is essentially the way General Motors cars (and probably others) were wired in the '50s & '60s. They ran on 6v and had 12v for hotter spark for starting. As long as you still have 12v supplied to the ballast resistor when the key is on, it should keep running. The 12v bypassing the ballast resistor should quit after it starts because the coil is designed for 6v and will overheat if you leave it on 12v.
I agree your symptoms don't make sense if you added the extra bypass wire from the starter button to the coil+ and retained the ignition wire from the ignition switch to the ballast resistor.

 

[Michael Oritt]

Bob--

I put an ohmmeter between the now-disconnected wire and a good ground. The needle swung to the middle of the scale as if there is a "partial ground" though the needle pegs when I touch the leads together.
Is there suxh a thing as a partial ground?. The wire is 14 gauge so it certainly is heavy enough to provide enough continuity to give an accurate reading.

As I said in my first post, with the power wire to the coil coming off the ballast resistor as recommended in the Mallory diagram the engine starts virtually instantaneously and I am happy to forego higher starting voltage to the coil.
It is simply perplexing!

 

[gonzo]

Could the now disconnected wire act as a "resistor". Later model Corvairs had a resistor wire connecting to the coil to provide "hot starts"

 

[red57]

Were the suggestions you read online for the Unilite system/coil you have or something else? Perhaps the Unilite coil has internal protection to prevent running on 12v. And even though your added wire theoretically sends a full 12v to the coil, the voltage delivered while cranking may be low enough for it to work for starting but when the starter quits drawing juice the voltage rises and the coil quits???
I enjoy mysteries as much as anyone, but I guess I'd go back to the system you had.

 

[Michael Oritt]

Were the suggestions you read online for the Unilite system/coil you have or something else? Perhaps the Unilite coil has internal protection to prevent running on 12v. And even though your added wire theoretically sends a full 12v to the coil, the voltage delivered while cranking may be low enough for it to work for starting but when the starter quits drawing juice the voltage rises and the coil quits???
I enjoy mysteries as much as anyone, but I guess I'd go back to the system you had.

Hi Red--

At this point I do not remember what coils people were using when they said they had wired their systems for higher starting voltage. In any case it is confusing that merely by eliminating the jumper from the start circuit to the coil positive everything works fine--as it did before I went down this path. In any case I will not lose any sleep if we don't figure out the answer!