1. Registration trouble? Please use the "Contact Us" link at the bottom right corner of the page and your issue will be resolved.
    Dismiss Notice

No More Bad Condensors

Discussion in 'Early CJ5 and CJ6 Tech' started by 1967 CJ5A, Oct 18, 2019.

  1. Oct 18, 2019
    1967 CJ5A

    1967 CJ5A Mike

    Raleigh, NC
    Joined:
    May 12, 2012
    Messages:
    613
    After several instances of brand new or nearly new condensors failing, I gave up on points ignition in both of my Jeeps and bought a Pertronix module for one and HEI for the other. But when I bought another old vehicle (not a Jeep this time :() I decided not spend that much money to keep a tired out 50 year old engine running.

    I drove myself crazy with one bad condensor after another. The engine would run fine, until with almost no warning, it would sputter once or twice and then die completely. I never had a single condensor last more than a couple hundred miles, except for the one that was in the car when I bought it (probably at least 20 years old) which I kept as a spare.

    Are points ignition systems really that unreliable? In the past, no. But today it seems like the parts market is full of very low quality condensors that just don't last. The funny thing is, the underlying technology of a capacitor is leaps and bounds better than it was when these vehicles were new! There is really no excuse for these failures.

    Knowing this, I decided to gut an original condensor and put a modern capacitor inside that is much smaller, cheaper, and more robust. I cut the end of the condensor off with a pipe cutter, being careful not to damage the rubber end seal. Here is what's inside:

    [​IMG]

    This roll of metal foil and insulating film is what forms the capacitor. There are actually two separate sheets of foil that form two parallel plates which can hold an electric charge. One piece of foil contacts the outside of the can, and the other contacts the wire lead. Seems like not much could go wrong here, right?

    The problem is that neither the can nor the wire lead have a robust connection to the foil - they just lightly touch! Poor manufacturing tolerances, temperature changes, and more can easily degrade this connection.

    In this photo and the photo above, you can see the signs of arcing between the wire lead and the foil (dirty and charred looking black spots). Once arcing starts, the connection will degrade, causing more arcing and before long there will be total failure.

    [​IMG]

    I selected a suitable replacement capacitor. It has the same capacitance as the old one, a high voltage rating (I chose 1kv - there are going to be very large transient voltages across it), and low equivalent series resistance (a type of parasitic loss). It is much smaller than the condensor body and only costs around $3.
    Capacitor

    [​IMG]

    I drilled a small hole in the end of the condensor body and one lead of the capacitor through it.

    [​IMG]

    Then I soldered it in place.

    [​IMG]

    At this point, I forgot to keep taking pictures. Sorry!
    The next step was to fill the condensor about 2/3 of the way up with JB Weld to hold the capacitor in place. I let this harden first. Then, I soldered the other lead of the capacitor to the orange wire. I filled the rest of the can with JB Weld and pushed the rubber seal into its original position, then did my best to put a little crimp on the can to hold the rubber seal.

    I completed this in May and it has worked flawlessly since then. The car is my daily driver and I have put about 3000 miles on it without any hiccups... well, not from the ignition at least! :D
     
  2. Oct 18, 2019
    Howard Eisenhauer

    Howard Eisenhauer Super Moderator Staff Member Sponsor

    Tantallon, Nova...
    Joined:
    Nov 22, 2003
    Messages:
    5,879
  3. Oct 18, 2019
    47v6

    47v6 junk wrecker! Sponsor

    Washington DC.
    Joined:
    Oct 25, 2006
    Messages:
    4,627
    This excites me a lot more than it should!!! Awesome!!!!!!!!!!!
     
    Jrobz23, dozerjim and ITLKSEZ like this.
  4. Oct 18, 2019
    FinoCJ

    FinoCJ 1970 CJ5 Staff Member Sponsor

    Denver, CO
    Joined:
    Jul 18, 2013
    Messages:
    2,436
    AWESOME....I have had a few bad condensors as well - one left me stranded on 5 lane urban interstate hwy in the middle of morning rush hour traffic on my way to work 2 days after I installed it. At that point I gave up on points...not so much in theory but just like you, in terms of finding reliable parts. Of course, that lead to swapping out the distributor on the sbc, which lead to some firewall mods, which lead to intake and oil pan removal, which has lead to broken oil pressure line and swapping the oil filter canister....all because I don't trust points condensors anymore....
     
    Jrobz23 likes this.
  5. Oct 18, 2019
    Glenn

    Glenn Kinda grumpy old man Staff Member Sponsor

    Apopka, Fl
    Joined:
    Sep 21, 2002
    Messages:
    9,235
    Excellent! Condensors used to last forever. Same here with condensor failures.
     
    fhoehle likes this.
  6. Oct 18, 2019
    jpflat2a

    jpflat2a what's that noise?

    Riverside CA
    Joined:
    Jul 30, 2003
    Messages:
    7,836
    Like Glenn says, condensers used to last forever.
    Think of all the good used ones we tossed out when we changed the points.
    If only we knew back then....we'd have a coffee can full of used condensers.
     
    dozerjim, Dandy, Hellion and 2 others like this.
  7. Oct 18, 2019
    Glenn

    Glenn Kinda grumpy old man Staff Member Sponsor

    Apopka, Fl
    Joined:
    Sep 21, 2002
    Messages:
    9,235
    It used to be done (changing condensors) because it was a good practice.....too bad we didn't know a better practice would have been to stockpile a bunch of new ones and like Jim says, save the old ones.
     
    Hellion likes this.
  8. Oct 18, 2019
    47v6

    47v6 junk wrecker! Sponsor

    Washington DC.
    Joined:
    Oct 25, 2006
    Messages:
    4,627
    Yeah, but 1967 CJ5A solved this issue with a soldering iron. This solution is perfect ingenuity to work around junk and make it better than new. This idea is brilliant.
     
    Jrobz23, ITLKSEZ and Glenn like this.
  9. Oct 18, 2019
    Glenn

    Glenn Kinda grumpy old man Staff Member Sponsor

    Apopka, Fl
    Joined:
    Sep 21, 2002
    Messages:
    9,235
    It is a great idea! I'm very impressed.
     
    dozerjim likes this.
  10. Oct 18, 2019
    PeteL

    PeteL Member Sponsor 2019 Sponsor

    Hills of NH
    Joined:
    Aug 3, 2003
    Messages:
    6,514
    Well done. Model T Ford guys have been doing something like this for many years.

    But this whole condenser thing is cuckoo, IMHO. I have NEVER had a bad one in sixty years of all kinds of points ignition vehicles.

    Yet it seems undeniable that new ones are garbage. What's crazy is that building a good automotive condenser should cost only pennies. Why doesn't someone have a source of quality OEM condensors? It is nuts.
     
    dozerjim and 1967 CJ5A like this.
  11. Oct 18, 2019
    Glenn

    Glenn Kinda grumpy old man Staff Member Sponsor

    Apopka, Fl
    Joined:
    Sep 21, 2002
    Messages:
    9,235
    Are condensors voltage sensitive?
     
  12. Oct 18, 2019
    47v6

    47v6 junk wrecker! Sponsor

    Washington DC.
    Joined:
    Oct 25, 2006
    Messages:
    4,627
  13. Oct 18, 2019
    1967 CJ5A

    1967 CJ5A Mike

    Raleigh, NC
    Joined:
    May 12, 2012
    Messages:
    613
    Thank you. I can't take full credit though. I had been toying with the idea of doing this for a while, but before I tried it for myself I did some searching and found that others had already successfully done this in the past. Here is one example: http://www.nonlintec.com/sprite/cap_failure/ This uses a larger capacitor though and mounts it on the coil. Ideally you really want the capacitor to be as close to the points as possible.

    Yes, there is an upper limit to the voltage they can withstand before the dielectric film breaks down and lets the two pieces of foil short out.
     
    ITLKSEZ likes this.
  14. Oct 18, 2019
    ITLKSEZ

    ITLKSEZ Volvophilic

    Post Falls, ID
    Joined:
    Aug 13, 2015
    Messages:
    3,487
    I’d copy that if I understood the witchcraft of electricity.
     
    fhoehle, dozerjim and Hellion like this.
  15. Oct 18, 2019
    FinoCJ

    FinoCJ 1970 CJ5 Staff Member Sponsor

    Denver, CO
    Joined:
    Jul 18, 2013
    Messages:
    2,436
    that is close to what I say when I watch the fab skills some of you have with welding, machining, wood work etc....
     
    Glenn likes this.
  16. Oct 18, 2019
    Glenn

    Glenn Kinda grumpy old man Staff Member Sponsor

    Apopka, Fl
    Joined:
    Sep 21, 2002
    Messages:
    9,235
    So then, would a 24 volt system be only able to use a 24 volt condensor? Is there a problem using a 24 volt condensor on a 12 volt system?
     
  17. Oct 18, 2019
    ITLKSEZ

    ITLKSEZ Volvophilic

    Post Falls, ID
    Joined:
    Aug 13, 2015
    Messages:
    3,487
    But... but... that stuff is easy! :whistle:
     
    fhoehle likes this.
  18. Oct 18, 2019
    Alan28

    Alan28 Well-Known Member Sponsor 2019 Sponsor

    Châtillon en...
    Joined:
    Oct 21, 2012
    Messages:
    1,641
    The fact is that there are many qualities and prices... You always can get high quality in electronic components but price can be x 100 !
     
  19. Oct 18, 2019
    PeteL

    PeteL Member Sponsor 2019 Sponsor

    Hills of NH
    Joined:
    Aug 3, 2003
    Messages:
    6,514

    I recall that on my f-heads the 6 volt and 12 volt were the same part number at my FLAPS, years ago.
     
    Glenn likes this.
  20. Oct 18, 2019
    47v6

    47v6 junk wrecker! Sponsor

    Washington DC.
    Joined:
    Oct 25, 2006
    Messages:
    4,627
    You don't need to invent the capacitor or even the procedure for adapting it. You had the idea, looked it up, bought the parts and executed the solution. None of us here invented the jeep, but we adapt it all the time to our own requirements. Thats the brilliance in it. Ingenuity. The ability to find a novel solution to an everyday problem and bypass the available garbage.

    This is a quintessentially American trait and why Jeeps are an American icon. Infinitely adaptable in any situation with available parts or ideas on the fly to keep going. Roadblocks or closed doors just beg a workaround.
     
    fhoehle, Alan28, Dandy and 2 others like this.

Share This Page

New Posts