Does a Mallory unilite need a ballast resistor?

This weekend a buddy of mine installed a Comp 9000 distributor in his 400 and the truck wouldn't even start. So I tested the unilite module and it was bad, it was a constant voltage and didn't trigger. I had an extra module, so we put that in and the truck started right up. I got the timging set and the truck was running great and then it just shut off. It ran for maybe 5 minutes. Checked the module again and this time there was no signal at all coming out of it. The wiring and the module were hot. At the same time, he installed a Mallory Pro-Master coil. So, my question is, does the coil need the ballast or is there some other trick that can be done so it doesn't fry another module? I have two different vehicles that had the unilite system in them and neither of those had ballasts. Is there something that would cause it besides voltage spikes?
[addsig]

Not at all. Infact if you read the instructions they say the factory resistance wire is a viable alternative. However, ballast resistors are a better way of keeping the voltage constant.

<font size=-1>[ This Message was edited by: 2FST4U on 5/9/05 7:35am ]</font>

The Unilite module DOES require a ballast resistor. Only alternative is if you run an ignition box - i.e. MSD 6 - then you will not need the resistor.

I learned this the hard way back when I had a 302 in the car. A buddy had a unlite dizzy he wanted to sell. I installed it and fried the module. Read the instructions online and found out that full voltage is a bad bad thing with the modules.

I had to buy a new module for a dizzy that I didn't even keep.
[addsig]

Ah, that makes sense. The guy hooked it up to a 12 volt wire and ISN'T running an ignition box of any kind. Both of the trucks that I had the Unilite in had aftermarket ignition boxes in them so that would be why they didn't fry. I know the Mallory tech guy told me to hook the unit up to the red with white striped wire on my 82. So now I just have to find a ballast and put that on when I install the new module in.
[addsig]

I'm pretty sure that 10v is the max for the Unilite.

I know I had one in my '65 and was seeing about 9.5v (w/stock pink resistance wire). I checked with Mallory to be sure I wouldn't fry it with that much voltage. Tech said as long as it's under 10v I'm good to go.

Never had a problem. Great dizzy in my book. [img]/phpBB/images/smiles/icon_tup.gif[/img]
[addsig]

One thing that confuses a lot of guys, the Unilite itself doesnt need a resistor, it can run on 12-14+ volts, per Mallory, HOWEVER, the coil needs to run a resistor on the positive side

Why? Because the spikes happen on the negative side of the coil, not the positive side of the Unilite.

When the Unilite "makes a ground" for the coil, power rushes through the unit toward that ground. It should dissipate through the dist, the block, back to ground, but big spikes can surge through the trigger unit

Same on points, the power to the coil is grounded through the distributor, run without a ballast or resitor wire, you burn points.

In addition, whenever you check voltage at a coil, let the motor run a while, as the battery charges back up, it can be up to 2 volts higher than when you check it at start up.

I run a Mallory Unilite, and found my factory resistor wasnt enough after a few minutes and almost non existent when at fast idle.

Check close, they are super triggers when wired right, if you cheat on setup they burn easy