Topic: Failure of Electronic Distributor Modules


Drbrown    -- 06-17-2023 @ 11:18 AM
  My search found no posts about the subject but expect it has come up historically. My '47 came with a Pentronix module 2-bolt distributor. It ran fine in the early years of my ownership but then failed. James Lindner a/k/a Bubba, then the go-to guy regarding electronic distributors but who is long retired, replaced the module and provided a new coil with internal 3 ohm resistance, but the new module quickly failed. He, Pentronix and I tried unsuccessfully to identify the problem. Wiring, switches and distributor cap/rotor checked okay. Suspicion came to rest on the Alternator possibly putting out voltage blips in excess of the module's 14.5 volt tolerance. Testing of the new Alternator, a Chinese rebuild, confirmed it was malfunctioning. I had another Alternator replacement carefully tested and installed a volt meter on the dash to monitor it. The module failed again. In frustration I had Charles Schwendler make/provide me with a points distributor and coil. It worked fine for about 4 years but the coil overheated. While now in Charlie's hands for repair/testing, I installed a good 3 ohm internal resistance coil and again tried a spare pentronix module. I again burned out an expensive module .... so I give up on modules. Question: Has anyone had this problem ?


1931 Flamingo    -- 06-18-2023 @ 10:42 AM
  I've had it happen.
I believe the modules are voltage sensitive. Mine charges (^V) aat about 7V and has been fine fnow for about 4 years. FWIW
Paul in CT


trjford8    -- 06-19-2023 @ 7:54 AM
  Any type of electrical spike will knock out a module. First encountered it years ago with a GM distributor. Recently had two Pertronix coils fail. Returned to a points distributor with a new coil and ballast resistor and so far it's working perfect.


Drbrown    -- 06-19-2023 @ 3:39 PM
  Flamingo: Max 14.5 volts and there's a minimum too. I believe generators with separate voltage regulator put out a more stable voltage than Alternators. ...... trjford8: I've decided to stay with a points distributor ..... Charlie Schwendler fixing mine now and will make a spare. Distributor bodies are rare and expensive so he's changing out a Pentronix one I have. My spare Pentronix module and mounting plates go to storage. Not of any assistance to me now but Pentronix on-line gives interesting data: (1) should use carbon core or spiral wound plug wires because copper etc emit signals that can damage the module. However those wires slow down the transmission of the spark. Their made-up kits are only for cars back into the 1950's that have the top mounted distributors so one would need to custom make to reach a front mount distributor; (2) The site describes how one can test a Pentronix module with some jumper wires; (3) can increase plug gap o.007 with a module.

This message was edited by Drbrown on 6-19-23 @ 3:43 PM


FordFreak    -- 06-20-2023 @ 5:37 AM
  Are you using the Igniter I, or the Igniter II version?


1952 Ford F1 Pickup
1965 Falcon Sprint


Drbrown    -- 06-20-2023 @ 5:44 AM
  Before "Bubba" retired I bought two units from him marked "Ignitor D-57-22". The instructions with them refer to part # 1285LS. They are 12 volt, for an 8 cylinder.


37RAGTOPMAN    -- 06-20-2023 @ 3:05 PM
 
did you check the grounds from the engine to the battery ? and engine to the chassis,
seems to me there is a spike,
loose or corroded,,,, wiring somewhere along the line,
hope this helps 37Ragopman , Maine





Drbrown    -- 06-23-2023 @ 9:34 AM
  37ragtopman: Great suggestion. Over all these years no one has suggested that as a source of a voltage spike. I replaced all the wiring, from battery and Alternator to everywhere except the tail lights, but a connection may have become loose. As well there's a fuse board with one for the ignition circuit that could be acting-up. Bottom line - I'm not an electrical engineer but any resistance would seem to reduce voltage rather than produce a spike, which is why I have blamed the Alternator.


Drbrown    -- 06-29-2023 @ 8:19 AM
  The Conclusion: Regarding the failing of Pentronix modules in my car, no definite source of a probable voltage spike has been found. The units simply fail. An electrical interruption would have been just that, and the system would have come back to keep functioning. Pentronix provides stock responses which are of no help. My engine does have spiral SS plug wiring which Pentronix says is best for the module (but hinders spark transfer). System wiring is new, oversized and secure. So my suspicion about the diodes inside the 12v alternator (converted before my ownership) playing games with me remains - they are fine when tested. Converting back to a generator with voltage control box is beyond my interest. Yesterday I received from Charles Schwendler his rebuild of my points distributor and he is now making a backup spare for me. Note: When finishing his work he mounts it on his "test Engine" and runs it for a time. Charlie recommends I use my here-to-fore new/unused internal resistance coil I obtained from Bubba, testing at 3 ohms resistance. (A "did not know" item ..... Charles use the work with Bubba before Bubba retired).


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