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Helloooo Vetters!!!
I have a 1979 L48. I have only had it for 1 year....Purchased last summer. I have gone through 2 ignition modules. The first one last summer shortly after I purchased the car. Then again this summer driving home from the Woodward Cruise. (Thankfully it didn't quit on Woodward) following the advice of a friend who owns an 81 "always carry a spare module and coil". Which I did and replaced it in a parking lot and drove her home. The module I had in the car was a PerTronix with a PerTronix Flame Thrower Coil. The module literally lasted less than 1000 miles. I cracked it open out of total curiosity. It is obvious that it burnt. Just for clarification.....Yes I used the grease.
So Vette heads....her are my questions and concern.
1.....Is there a particular module that will last longer than any other?
2.....How long should a module last?
3.....Could something else be causing the module to burn out so quickly?
So Vette heads....her are my questions and concern.
1.....Is there a particular module that will last longer than any other?
2.....How long should a module last?
3.....Could something else be causing the module to burn out so quickly?
Any input or advice would be greatly appreciated.
Cruise Safe
Besides heat.....not really, other than poor manufacturing.
You said you used the grease.....did you clean the distributor base inside and/or scuff with a scotchbrite? The grease actually helps transfer the module heat to the distributor base which is the heat sink for it. It is important the the heat be able to transfer as easily as possible.
HEI Modules are supposed to last for years......some old Vette's, Camaro's, etc.....have the original 40 year old module in them.
I would swap brands.....I never have had bad luck with Standard Blue Streak or NAPA Echlin.
I have the PerTronix in one car and a Proform brand in the other car. Both have been going for three years without any problems. The Proform came with a distributor tune-up kit. $79 for module AND coil, distributor cap, rotor, wire harness, capacitor, weights, 3 spring sizes and adjustable vacuum advance. All were exceptable quality, but I cleaned up the old weights. Also took some adjustment to get new plastic bushings to fit.
Hay Kersh
Thank you for your input.... My dizzy has been tuned as well..... New weights, bushings, vac advance can, cap, rotor, coil, wires, plugs. The dist. it self is realtivley new.
Not sure about the construction of the Pertronix unit, but OEM and name brand modules like Standard, BWD, and Napa have current limiting circuitry to prevent overheating.
Have you contacted Pertronix about this? They might do a postmortem to see what the mode of failure was. What was/is the condition of your secondary circuit? Cap , rotor, wires, plugs.
How did the car run prior to failure. Any misfire?
Hay Mrvette
I have not contacted PerTronix. The mod and coil were purchased on Amazon and they issued a refund. But all other components including the dizz unit itself is all new. Although we were crusing on Woodward.... And I did notice a very slight miss. We stopped for some snacks. And the girfriend said she was tired and wanted to go home (GOOD CALL BABY) And it died on the way home.... So happy we weren't on Woodward when it quit.
Thank you for your input
Get an original (OEM) GM module, they are the best, longest, lasting ones. If you had to, in a pinch, you could get one from a junkyard. And yes heat transfer is critical for these things to survive so check the mating surfaces carefully and use the heat transfer compound. Good Luck!
No expert on HEI but have had my share of failures, even 40 yrs ago. Chevy dealer back then said, about 60,000 miles was the life cycle of a modge. Mine croaked at 61,000 in a Monte Carlo.
By the way. A zip-lock bag of ice cubes laid on the coil cover will usually get you home. The cooling effect makes the circuit board make contact again, briefly.
I don't believe the modge itself is to blame here. I believe its another issue that is taxing the modge prematurely.
The most obvious has already been mentioned. Heat Sink Compound.
Secondly, are all the pins making excellent contact with the modge? The wires inside of that dizzy are in constant movement with RPMs changes.
Third:
Remove the coil dust cover. There will be four bolts holding the coil. Remove coil and check condition of the spring under it. And is there a rubber washer there also?
When you reassemble the coil, wire brush the corner of the coil with the wire terminal down to bare metal. That is a powder coating on there that may hinder a good ground for the entire unit.
As far as purchasing a module, I have seen ones for $19.95. Steer clear. I have seen ones for $100. Not likely worth it.
What I don't know is, if the module mounting holes & screws are in the exact same location regardless of manufacturer. If they are, then you could try Accel, MSD, GM, DUI, Mallory or whatever.
Some yrs back, I had a fairly new MSD modge force me to call a flatbed. Not happy, no spare. So I called MSD next day. They sent me two brand new modges free of charge. So, what does that mean? They knew there was a bad batch of modges out in circulation? Or was it a good gesture for P.R work? IDK
(But I still stand behind MSD today)
Last edited by HeadsU.P.; Aug 23, 2021 at 03:12 PM.
If you have the wrong coil, the primary windings may have too low an impedance drawing more current than the module can handle. This shows up as heat, eventually burning up the module.
My 40 y.o. GM HEI will throw a spark 3/4" long. Aftermarket Napa outdone etc might make 1/4" spark,
.
Napa buys from Standard, a reputable company. Autozone buys from Wells, cannot vouch for their quality. Do not buy a no name module, especially on ebay.
Last edited by Mrvettenick; Aug 23, 2021 at 07:27 PM.
If you have the wrong coil, the primary windings may have too low an impedance drawing more current than the module can handle. This shows up as heat, eventually burning up the module.
Yep 4 pin module uses red and yellow wired coil and 7 pin uses red and white wired coil. If you swap them you end up with more heat on the module and a shorter module life.
Last edited by Gunfighter13; Aug 24, 2021 at 08:29 AM.
Ignition Mudule
