Pertronix To Replace Unilite In Mallory Distributor?

[Circlotron]

^^ I had a Peugeot 404 with a Ducelier distributor that was like that. IIRC the vacuum moved one side of the points around in an arc (pardon the pun) while the other side that had a much larger contact stayed still.

Edit -> thinking further, it probably wouldn't have changed the dwell with vacuum, but it was unusual. I think the advantage was the grounded contact was fixed directly to the distributor body, not to a moveable breaker plate, and so didn't rely on a stranded flexible wire for earthing that can sometimes break off.

[JoePorting]

I found the bad Unilites modules run fine when they are cold, but cut out when they get hot. That was back in the 1980's, so maybe they are different now.

Although just to clarify, I was 18 years old back around 1981 running solid core wires at the time and didn't know they would damage the module. Learned the hard way.

[autogear]

There is a 'filter' you can put in-line with the Unilite to keep a dirty power supply from cooking the module. It bears mentioning that Unilites NEED the car to have adequate, clean grounds.

[DaveMcLain]

Dave Mc,
Which point dists changes the dwell angle when the vac adv operates? I know it is not the Delco dist because the points plate rotates, when activated by the VA, so the angle doesn't change.

Some Fords did it to some extent but some Chryslers did it a lot so much so that if the points were set a little short on dwell when the vacuum advance would pull in it wouldn't have enough and it would misfire, not from too much timing but from not having enough spark.

[Geoff2]

Dave,
I am aware of the single mounting point used on Chrsyler dists, but have never looked closely to see how much that it affects dwell. I have great respect for Ch engineering & would have thought that they would design a good system. Looks like a trip out to the garage....

[statsystems]

Right now I have a Ford 428 with a Unilite distributor on my dyno and the module is bad, no spark. I checked on a replacement Unilite module and it is over $100. The Unilite is notoriously unreliable so I checked and sure enough Petronix offers a replacement for a Mallory Unilite distributor has anybody used one before?

If you are killing the Unilite, you are doing something wrong. Don't buy the standard Unilite, get the e-model one. I don't remember the exact part number but if you want I'll get it for you.

[DaveMcLain]

Right now I have a Ford 428 with a Unilite distributor on my dyno and the module is bad, no spark. I checked on a replacement Unilite module and it is over $100. The Unilite is notoriously unreliable so I checked and sure enough Petronix offers a replacement for a Mallory Unilite distributor has anybody used one before?

If you are killing the Unilite, you are doing something wrong. Don't buy the standard Unilite, get the e-model one. I don't remember the exact part number but if you want I'll get it for you.

It was already dead and they are known to be failure prone junk. I bought the Pertronix replacement, put it in and ran the engine it worked fine.

[statsystems]

Right now I have a Ford 428 with a Unilite distributor on my dyno and the module is bad, no spark. I checked on a replacement Unilite module and it is over $100. The Unilite is notoriously unreliable so I checked and sure enough Petronix offers a replacement for a Mallory Unilite distributor has anybody used one before?

If you are killing the Unilite, you are doing something wrong. Don't buy the standard Unilite, get the e-model one. I don't remember the exact part number but if you want I'll get it for you.

It was already dead and they are known to be failure prone junk. I bought the Pertronix replacement, put it in and ran the engine it worked fine.

I've been using them since 1982 and still do. I've only failed one. If you are killing the Unilite, it's something you are doing. They are not failure prone.

[In-Tech]

It's not necessarily that anyone is doing anything wrong, they can work flawlessly on one vehicle and the next fail all the time. As in any electronic component, they are all strained by "noise".
I've scoped + AND - over 120v on a 12v system due to many things but mostly faulty alternators that still apparently to the end user charge, so they think nothing is wrong.

The later unilite modules had some more filtering safety.

A big fat capacitor does wonders in "noisy" environments.

[DaveMcLain]

[/quote]


I've been using them since 1982 and still do. I've only failed one. If you are killing the Unilite, it's something you are doing. They are not failure prone.[/quote]

I've been using one too for 15 years in the Flathead V8 that's in my T bucket without problems but they ARE known to fail often and without notice. This one was "dead" when it came in so who knows what happened. I think what probably kills most of them is by running without the right ballast resistor and coil with the correct primary resistance.