Unilite + 6AL issue

[minorv8]

Hi,

I have lately had some problems with the ignition. The setup is Mallory Unilite + MSD 6AL + Blaster 2 coil + MSD 8.5 Super Conductor wires. The engine is a Rover V8 (Buick 215).

I have had this same setup for 10 years and it has been totally bullet proof. Now, a month ago the engine died suddenly at 55 mph. Engine temp a stead 170 deg F. The diagnosis showed that the Unilite module test did not produce any spark. I had a spare coil with me and swapped that but still no spark. So I concluded that the module is dead. I had to tow the car home and replaced the module with a new one. The engine started immeadiately with the new module.

Last weekend I drove 80 miles to a airfield for some 1/4 mile testing. The last few miles crawling with the engine temp at about 200 deg F. The queue stalled and I shut down the engine. 5 minutes later it refused to fire and I had to push it away from the queue. Quick test with the Unilite module: no spark. I let the engine cool for about 15 minutes and it fired up again. I chose not to run any test runs at the strip, stayed for about 2 hours and drove home. Well almost, the engine died at 70 mph on highway, temp normal at 170 deg F. Again, module dead and no spark. I replaced the module with a new one and drove home. I shut down the engine, and tried to start it again. Well the bugger did not fire up. 10-15 minutes later it did...

So, looks like it is somehow temp related but if a module lasts a whopping 150 miles is not good for reliability.

2 days ago I tried to make the problem appear by letting it idle until the fan had run three times (it switches on at 200 deg F) but naturally it started immediately every time. This is an annoying issue; I have ordered 2 new modules for spares but that is also getting expensive. Any ideas to check when it dies again ?

No spark means that it is either module, coil or 6AL (6AL is mounted under the passenger set and it is not affected by any ambient heat).

Is it possible that the module gets too much voltage and that kills it ? The voltage is around 14 V when the engine is running.

Sorry for the long explanation, hope you can help me out.

[msdtech1955]

was there any heat sink compound applied to the module?

[minorv8]

Naturally, as per instructions.

[msdtech1955]

only things that can "kill modules"

1) excessive voltage
2) heat
3) poor grounds

[minorv8]

So, how to fix these issues ?

Excessive voltage: MSD wiring diagrams do not require any filter or resistor on 12V feed to module. Should one be fitted ?

Heat: 170-200 deg F is normal operation conditions of the engine. Surely the module specs must exceed these ??? Like already stated there is heat sink compound applied underneath the module.

Ground: the module ground is wired to the timing cover. Two thick ground wires are fitted between timing cover and the car body. All contact points are clean + copper paste has been applied to prevent any corrosion. If this is not enough the module specs are way too sensitive.

As a side note: if I replace the Msllory distributor with a magnetic trigger distributor like MSD Pro Billet, can I expect better reliability (less sensitivity to voltage/heat/poor ground) ?

[armcosurfer]

I used the same Unilite distributor in a couple of my racecars for over 15 years without any problems, I used a ballast resistor in the live feed to the Unilite-the Unilite module does not like a full 12 volts.

[minorv8]

It would be nice to get some replies to my questions from Tech Support...

[msdtech1955]

I used the same Unilite distributor in a couple of my racecars for over 15 years without any problems, I used a ballast resistor in the live feed to the Unilite-the Unilite module does not like a full 12 volts.

your right...the module is just now a trigger for the msd points lead ...
so, it would not matter if it only had 7 to 9 volts running to it... it would still put out the same trigger .

[msdtech1955]

It would be nice to get some replies to my questions from Tech Support...

we get 700 to 1000 calls a day plus 100 to 150 emails ..plus answer 50 to 75 forums a day ....( so keep that in mind():001_cool:

we just acquired Mallory in april...so time to time we miss a post or two.

if I was you ...put a lot of heat sink compound ,.and install a 8214

to cut the voltage down.

[minorv8]

I fitted a Mallory 700 ballast on the 12V wire running from ignition switch to the module. The ballast measured 1 Ohm across the poles. I don't know what it is supposed to do since the voltage is basically the same on either side of the ballast. I thought that it is supposed to reduce the voltage ?