Need help with Mallory Uni-Lite distributor/ProMaster Coil combo

[YerDugliness]

I've done the forum searches...not sure if I just don't understand (well, perhaps I AM sure I don't understand) or if this is a unique problem.

Not long ago my what I believe is a box-stock 5.0HO engine (other than the intake/ignition systems) stopped and would not fire up again. At first I thought the problem was fuel starvation so I rebuilt the Edelbrock Thunder Carb....still would not start. I pulled some plugs and they looked OK...but when I laid a plug against the header and cranked it there was no spark. Time to pull the distributor cap.

Well, the center electrode on the cap, the one for the coil wire, was just gone and in it's place was some sort of corroded looking gunk. Time for a new cap. I had some trouble getting the "shutter wheel" off and broke that, so a new shutter wheel was ordered, too.

I was certain it would fire up once those parts were replaced....NOT!

Still no spark at the plug. I called the Accel/Mallory group tech support and was told to take some measurements with my VOM...was told there should be full battery power at one of the terminals and different power (volts) at the other one depending on whether the control module was "blocked" at the gap between the infrared "windows" or not. When I got those measurements the tech guy spoke in such gobbledy-gook and was so impatient that I could not understand what else to do; hence, this thead.

Has anyone ever had trouble with this combo? One of the things the guy from the Accel/Mallory group asked was whether or not there was a resistor wired in....I can only say I think so. Leading from the positive terminal on the coil is a wire that leads to a small (1"X1"X3") white plastic block attached to the front of the head with a bracket, from which another wire leads right to the distributor. It looks nothing like the resistors I see in Mallory's literature.

So....I'm lost and I hope someone else will have had some experience with this issue. The tech guy from Accel/Mallory said the contol module was burned out....I hate to spend $100+ for a control module unless I know that is the problem and the tech guy either speaks a language I don't understand or is just too impatient to bother with my questions.

Anyone have any experience with this sort of problem? I can tell you that once I got the shutter wheel off the distributor drive shaft I did find the missing portion of the center electrode...it didn't burn down to nothing, it apparently broke off.

Whatever help anyone could provide would be truly appreciated!!!

Thanks in advance!

Dugly

[Rick Parker]

"the ballast resistor is wired inline on the positive side of the coil"


Testing the Mallory Unilite and E-Spark Ignition Modules

[YerDugliness]

Originally Posted by Rick Parker

"the ballast resistor is wired inline on the positive side of the coil"


Testing the Mallory Unilite and E-Spark Ignition Modules

Thanks, Rick!

I think, just judging from the reading I've done on the link you posted, that I probably need a new control module. The reading does drop to lower than 2.0V but does not recover to full battery voltage. I have to wonder if the loss of the coil post on the inside of the distributor cap might have damaged it. It was interesting about the charging system issue...but I have recently had the alternator rebuilt using only the highest quality parts and the business who rebuilt it assured me it would not fail again...I am currently living 120 miles from them, though....

Onward through the fog...but at least I have some understandable directions regarding how to do the testing. I'm pretty sure the while block must be the ballast resistor, as it is connected into the wire leading from the positive side of the ProMaster coil to the distributor. There is no "box" of the sort I've seen with MSD ignition systems.

Thank you SO MUCH, Rick!

Cheers!

Dugly

[Rick Parker]

Just beware of the need for a ballast resistor on the (+) side of the coil.

[YerDugliness]

Well...I did all the measurements in the article...the guy at the Accel group tech support desk says I should have full battery voltage at one of the terminals on the coil...not happening!!!

I do have full battery voltage at the firewall, where the solenoid is located. Is it possible the solenoid is defective and is not routing full voltage to the ignition system?

I'm sure nobody will be surprised to hear that I do not relish the idea of twisting myself into knots and spending large amounts of time under the dash chasing ignition circuit wiring...but full voltage at the coil just ain't happening, so....????

Cheers!!

Dugly

[MOTORHEAD]

what's the voltage on both ends of the ballast resistor ?

[YerDugliness]

Originally Posted by MOTORHEAD

what's the voltage on both ends of the ballast resistor ?

I tried to measure resistance (ohms) but did not think to measure voltage at the ballast resistor. I will do so at lunch and post the results. Thanks for the tip!!

Cheers!!

Dugly

[ffr 1137]

Having same issue on my Mustang. Don't know why your electrode blew, maybe "its time had just come", but the module's only job is to intermittantly energize coil just like the points did. A varying voltage on "+" coil terminal when cranking should eliminate the module as the prob. Mine didn't vary, nor did the timing light flash on plug wires so I've got a module coming. I've got a Mallory dist with pertronix guts and no ballast res.

[YerDugliness]

Originally Posted by MOTORHEAD

what's the voltage on both ends of the ballast resistor ?

Yes, there is full battery voltage to the ballast resistor.

Oops...did not check both ends...will do so this evening...

Cheers!

Dugly

[YerDugliness]

Full battery voltage at one terminal on the ballast resistor, 4.4 VDC at the other.

[bobcowan]

The ballast resistor is just that, a resistor. When the gap is open in the distributor, you'll get full battery voltage. When the gap is closed you should between 7-12 volts. To test the resistor, use an ohm meter, not a volt meter. In theory, the ballast resistor is designed to be either open or closed. It works or it doesn't. Voltage passes through or it doesn't.

If you're not getting a spark, it's probably the Mallory module. They have a nasty habit of failing; and it doesn't take much. I went through about 4 of them before I finally figured out it was the main battery switch. I know it's expensive, but replace it anyway. If that's not the problem, you'll have a spare. Eventually you'll need it.

Do you have circuit protection for the distributor? If not, you should install one. It's cheap and it works.

http://www.summitracing.com/parts/maa-29351/overview/

[MOTORHEAD]

The voltage drops only when current flows, so your module is turned "on". disconnect the connector at the dist. The voltage then should be approx 12 v on both ends of the ballast resistor. You did the test of the module as described in the link provided by Rick, voltage had dropped to approx 2v and did not recover as discribed in the test procedure, so the switching xstr is probably shorted, conducting all the time, which is why the voltage out of the ballast is low.
Module is bad. How long has this system worked for you before it failed ? Did it fail after the alternator rebuild ?

[YerDugliness]

I bought the car in 2008 and it had 3,000 miles on the odometer, it now has over 11,000. The alternator was rebuilt about 3,000 miles ago. Verbal history on the car is it was built in 1994 and I know the two previous owners, they both say they never had any trouble with the ignition system.

Cheers!!

Dugly

[YerDugliness]

Originally Posted by bobcowan

If you're not getting a spark, it's probably the Mallory module. They have a nasty habit of failing; and it doesn't take much. I went through about 4 of them before I finally figured out it was the main battery switch. I know it's expensive, but replace it anyway. If that's not the problem, you'll have a spare. Eventually you'll need it.

Do you have circuit protection for the distributor? If not, you should install one. It's cheap and it works.

http://www.summitracing.com/parts/maa-29351/overview/

Bob, is the item in your attached photo the Mallory version of a ballast resistor, or is it a different item with a different function?

I have no problem with spending the $$ it will take to make the system operational and my primary goal is reliability...my area of TX has quite a few National Forest areas and the car is used frequently for jaunts in areas where there is little in the way of civilization or help, so I am motivated to make sure the repair is durable.

I am convinced the control module needs replacing. I think I will replace the ballast resistor, too, and if the item in your post is a different item with a different purpose I will install one of those, too.

I want to fix it once...have no interest in short cutting the repair process or skimping on quality.

Thanks!!!

Dugly

[MOTORHEAD]

So the ign system had not failed in 11,000 mi, and 3000 mi since alternator rebuild.
All you can do is replace the module and add the circuit protection device shown by Bob to protect the module from voltage spikes. The only way the ballast resistor can fail is if it opened, which is rare, but they are cheap so replace it if you want. I would make sure that all the components you replace are the ones recommended by Mallory.
The only other thing you can do is check for voltage spikes with an ocilliscope if you can find someone with one who knows how to use it.
If you have a battery master sw, make sure the ign is off before you operate the master.
All Electronic ign systems are prone to faliure, MSD, Pertronics, etc,etc, Solid state components don't tolerate voltages or amperages higher than they were designed to operate at. You might want to replace the coil also. An intermittent short on the primary side could take out the module.
I hear what you're saying about being stranded in the woods! I changed my boat engs to electronic modules and they failed on me once. Next day the points and cond went back in !! Carry spares !!!

[YerDugliness]

I do have a master switch, it is located in the trunk at the +post of the battery. It is used only for security (removable key) and I have never operated it with the engine running.

Thank you all for your assistance...I am ready to call Accel/Mallory and use their best quality parts. I'd rather spend the $$ on good parts than on towing/transporter fees. New module, new ballast resistor and the protective device mentioned by Bob C...plus a second control module for a spare, I think...

Just curious...I did try to measure resistance on the ballast resistor and do not know if I used the correct range option...what kind of numbers would indicate acceptable resistance in Ohms? My experience with Ohms is all related to my lifelong interest in audiophile gear and numbers like 4, 8 and 16 Ohms are common...probably not the figures I should be expecting in this application.

Thanks, again, everyone!!!

Cheers to you all!!

Dugly

[MOTORHEAD]

Ballast resitors vary a bit, but generally between 1.2 to 3 ohms.
Good luck !
Ted

[bobcowan]

Originally Posted by YerDugliness

Bob, is the item in your attached photo the Mallory version of a ballast resistor, or is it a different item with a different function?

Completely different function. It protects the circuits in the distributor from spikes and surges.

From Mallory: "These Mallory Active Power Filters are designed for Unilite ignition systems that experience failures with ignition modules from voltage spikes. Voltage spikes are clamped and regulated by the Active Power Filters, keeping them from damaging the Unilite ignition modules."

[YerDugliness]

Sure sounds like what I need...something burned the coil wire electrode inside the distributor cap right off...the underside of the cap looked like oxidized magnesium where the electrode had been.
Most likely a voltage spike. My volt-meter is fairly stable...jumps a volt or two if I turn off the puller fan on the radiator, but otherwise no evidence of voltage spikes. I don 't think the ammeter works...never varies from the 0 at the center of the gauge.

Thanks, Bob!!

Dugly

[bobcowan]

Originally Posted by YerDugliness

Sure sounds like what I need...something burned the coil wire electrode inside the distributor cap right off...the underside of the cap looked like oxidized magnesium where the electrode had been.
Most likely a voltage spike. My volt-meter is fairly stable...jumps a volt or two if I turn off the puller fan on the radiator, but otherwise no evidence of voltage spikes. I don 't think the ammeter works...never varies from the 0 at the center of the gauge.

Thanks, Bob!!

Dugly

Oddly enough, I'v heard of and experienced the center electrode in the distributor cap leaving for another dimension. I'v heard of it on MSD's, and I'v experienced it on a Mallory.

When I had a distributor, I carried a spare cap, rotor, and module everywhere; along with the tools needed to replace them in the same bag.

The ammeter is probably working correctly. What it measures is the amount of amps produced above or below the required amount. An alternator only produces as many amps as is required - no more and no less. If you had a 250A alternator in a car that needs 35A, it's only going to produce 35A. The meter will read zero, because that's all that is needed. It essentially measures over and under production of electricity.

That's why most people install a volt meter, it gives you a better idea of what's going on with the charging system.