I have one of these (Mallory Unilite) in my Model A because they have the small cap and will clear the firewall better. Been running it for 10 years now with no issues. Went to the local burger joint Sat evening with no issues. On the way home the car would cut off at every red light and idle very rough when it would idle at all. I have swapped carbs with a known good one, no change. I have replaced all the plugs and wires, no change. The engine is a 350 Chev and the car is a 28 Model A sedan. SO , I believe it is in the dissy...........got any ideas? Do the sensor units go bad? If so will it still run at all? I have searched here and on the Web for answers. I have contacted Mallory and have got no answers from them. THANKS in advance for any help.
sometimes the "brain" goes bad in those.....i had it happen to me.......im no expert but i did stay at a motel 6 once........
The Unilite module is susceptible to two different problems: dirt, and electrical spikes. I'd check your wiring, grounds, battery voltage, & coil to verify everything's in working order as well...might even test the alternator & regulator if it has an external unit. Might look at the cap & rotor carefully as well.
I have had 1 go bad since I put in the Unilite, car was very very hard to start, had to use ether, once it got going it ran OK,I replaced it and that took care of it, now carry a spare, there about $85 from Summit
Sensor units do go bad, usually due to operator error of one sort or another. Most of the time it's due to electrical spike. If you are not running a ballast resistor, it has finally caught up with you. They also tend to go bad if they are left connected when jumping a battery or charging a battery. They are very suceptible to electriucal disturbances caused by messing with wiring while the unit is connected. There is a test that can be done with a business card to tell if the modual when out. You can find it here: http://www.malloryperformance.com/pdf/UniliteTest.pdf I have had lots of luck with them in the past, and every time I have lost one it was due to my own absent mindedness or screw-up..... not a cheap mistake. They sell repair kits but I think they are close to $100 now.... almost as cheap as some other distributors. If you are looking for a similar method of ignition, you might consider using a stock type points distributor with the pertronix Ignitor system. They are a little more hearty and use a Magnetic pickup rather than a LED photo sensor.
Issues I've seen with Unilites in the past.... susceptible to voltage spikes, bad/intermittent grounds, low voltage, high voltage (no ballast resistor), dirt. Shouldn't be a big deal to eliminate the causes one by one.
I went through a lot of trouble with a unilite and I found out a few things. It has to have the right coil , the power filter and it needs to be grounded properly. Some of that info wasnt in the instructions, so I called the tech line and got some usefull tips. I remember getting a replacement module from summit for alot cheaper than 100.00 , might call them and ask. Seemed like a lot of stuff snowballed from just a distributor change.
I'm gonna jump on this one. I have had nothing but trouble with mine from the get go. I'm "trying" to run the electronic dizzy with the ignitnition box and upgraded coil on my 42 flathead. I had it in and going and it died stranding me in a parking lot...my bad. I had the incorrect plug wires. They need to be very specific or the unit will take a dump. One new "brain" from Summit later (approx $80.00) and it won't start at all. Sent the unit back to Summit and they forwarded a replacement brain. Hooked everything up last night with the improved ground as well...nothing. I've just about had it. Atleast my old crab dizzy works everytime I bolt it back on. I guess "new" isn't always better.
Im not placing blame on the sales guys at summit, cause Ive gotten some good service from them, but I wish either them or myself would have had the thought to ask what "complete package" is needed to get this thing to work. It would have made things easier. I had a previous unilite that ran great from the time I bought the car untill I sold it 5 years later, but the latest one was a pain to set up. I dont know what Im buying for the next project but it wont be a mallory.
OK, I need to make a couple things clear. FIRST......I do not know anything. Second, this car has run for over 10 years with this set up. Nothing was changed. Just took it for a ride.....worked well on the start of the ride and not so well on the end of the ride. It did not leave me stranded, but I am concerned that it was about to. I have no problem buying a new brain for 80.00 but sure would like to know that is the issue first. Alternator is working properly. No electrical spikes that I know of. Has the right coil and a balast resistor installed. So back to my question, when your wend bad did it just go a little bad or leave you stranded. The fact that it still runs is what I do not get. OK guys thatks for all of the help. I will see what I can do with it tonight.
Unilites are hateful things. As others have said they are susceptable to voltage spikes, mallory will send you a list of what can cause these things to go titsup and when you read all the shit on the list you'll wonder why they work at all. What they do sell, and i use them, is an optical isolater that plugs into the pigtail from the distributor and it'll save the dumb mistake - like giving a buddy a jump start (which can fry the module). Usually the things work or don't work and since yours kinda works i think it is a related problem like the coil is weak or the voltage to the coil is weak and don't forget to unhook the tachometer or if it is unused make sure the wire isn't grounding to something. I don't think voltage going to the module is a big issue, the module dosn't actually do anything other than tell the coil when to fire and the voltage to the coil is supplied by the battery and that is why i'd be looking at those parts of the system. One other check, did you use the supplied connector and color code? If these got reversed so that the magnetic pickup was reading south instead of north the thing would idle but get very stupid when you tried to make power. If you used the connector then the polarity should be ok and not an issue.
When my Unilite went bad, it was just sorta bad - like hmmm, my car just doesn't seem as strong as it should, and it was always a bitch to start but otherwise ran smooth, so I kept thinking that it couldn't be the distributor because then it would be more obvious, right? It drove me nuts - I wasted so much time trying to find the problem and even swapped in a new power module on two different occasions - which sorta seemed to help, but then again...still didn't run real great. I also swapped coils, ballast resistors, even fuel pumps, etc., etc trying to find the solution. And yes, I had the Unilite set up right and it was all triple-checked by more than one pro who I really trust (and who often told me "dump the f'ng Unilite"). Finally decided it had to be the Unilite and replaced it with an MSD distributor and wow - huge difference. The car NEVER ran this good with the Unilite EVER. Afterwards, I beat my Unilite to death on the driveway for the years of aggravation and wasted time and $ it caused me - that was the best use I ever got out of it.
And this is why I ask these questions. I really am not an expert on anything. I can guess at the problem and then stand back and throw money at the problem. Sometimes I get lucky and sometimes I just end up with spare parts on the shelf and still have the problem.
Not saying you have changed anything...but we're trying to give you some things to check...ground cables flex, corrode & deteriorate...coils go bad...caps crack...rotors corrode...etc. Momentary electrical spikes occur, even when alternators "appear" to be working OK. Electrical components, including alternators & Unilite modules, work partially/intermittently. Those are all things I would check BEFORE I shelled out the $80.00. Sorry we couldn't be of more help...
Before you sink any money anywhere, check all your connections. A loose connection will cause the issues you are having. Something like a loose nut on the coil/resistor/ground. I ran a unilite for years on a daily driver without any issue.
You know.....I have two old fashioned Mallory dual points that work just fine. I have one in my 454 and one that I boxed up and was about to send to Mallory to make it electric. Now I'm biginning to wonder. Hhmmmmmmmmmm
I ran one in a 235 for yrs with out any trouble.........but had to replace it when it started acting up... almost went crazy trying to figure it out.. it would always start, idle ok but got to where it would die at hi-way speeds.. and sometimes at slow speeds but would always fire back up.. I also did the test per mallory instructions , showed good.... I finally replace the module............no more problems after that.. just like this one.................http://www.centuryperformance.com/mallory-unilite-and-e-spark-testing-spg-150.html
Replace the module with a PerTronix and you'll be happy! They make one that goes in the UniLite Dist.
Here is the cheaper replacement for a Unilite module. Same part, almost half the price. If you can handle yellow, that is... http://store.summitracing.com/partd...4294925143+400020+4294845520+115&autoview=sku
send it to GMCBUBBA on this forum, he will convert it. I have one on the way from him as we speak. old look+ new insides= good combo.
With a Unilite, you need to make sure you have a really good ground. I ground the ground lead with a ring terminal and serrated washers to a bolt hole in the intake manifold. Then also make sure your ground from the engine to the battery is a good solid connection too, or that the ground connection from the engine to the frame is good and solid if your battery's (-) terminal goes straight to the frame. The wires in the leads to the module are pretty thin with fairly thin insulation, so make sure one of the leads isn't coming loose from a connector, or getting chewed up where it goes through a jagged hole somewhere, or rubbing on something sharp on the engine or something. I've had a bunch of Unilites in a bunch of cars, and never had a problem with any of them. I think the people who have problems usually because of wiring problems, or from a big voltage spike like if someone welded on the frame without disconnecting the Unilite module first.
Mallory dropped the price of the modules recently. I think they're only about $30 now if you search around. It's a new part number and looks slightly different, but it works the same and bolts right in as a replacement to the old style one. A few years ago, I think the modules were a ridiculous price like $80.
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