In another post mentioned I am in the process of contacting manufacturers of auto condensers (capacitors to be honest here) to discuss where they're made and specifically if they're made in China. Comments here and on other forums have left me thinking there could be an out-of-box failure rate with the Chinese made condensers as high as 50%. This seems unbelievably high even for China. Knowing how manufacturing of small electronic parts not enjoying high consumer demand is conducted in China, I am 99% positive these condensers were produced by one company in one large run (possibly years ago) and have been and are being distributed by one or two Chinese jobber-type companies from existing warehoused supply. I further suspect these are failing for 2 reasons: poor manufacturing and heat...maybe in equal parts. So far I've learned
Standard brand of condensers are not made in China but made in Mexico and the man I'm talking to there says he knows of no failure trend in them and has asked for part numbers if I can produce them. He also added "keep those Chevy and GMC sixes running."
If you have ever torn one of these condensers apart you will see a design which is simple and subject to a few different types of failures. You'll see a cylinder which is made of a strip of aluminum foil with either gel or some type of film on one side which has been tightly rolled. It sits inside the canister but only touches that canister at one end (to keep it from shorting out along the side). The size, the length of foil, the nature of the coating...these are the things that determine the capacitance rating, voltage limit and temperature tolerance of this sort of device. Age and heat will eventually cause failure. The case provides one contact point---ground, and there's a wire soldered to a copper or brass disk which is insulated from the case by a rubber grommet contacting the other end of the internal cylinder. Dead simple. What can go wrong? I won't waste the electrons necessary to discuss everything but the main 2 things of rapid failure would be: contact is lost either where the case contacts the little aluminum foil/film cylinder or where the wire end connects it...creating an open capacitor or an intermittent one and/or heat and current causing the gel or film to degrade, collapse or shrink to the point the foil layers touch each other creating a short circuit. And heat combined with current could cause an instant failure in one made improperly or it could take a little while for this to occur. Heat for any capacitor is detrimental and in fact students of electronics are taught to begin their circuit troubleshooting by spraying a chiller on any capacitor they see...particularly electrolytic capacitors. Many times the reduced temp will make the device start working again. Let's go back to the lost contact issue. Let's suppose just for grins the little foil cylinder inside was made just a wee bit too short for the canister it fits inside of or let's say the canister wasn't crimped to the right point to press the cylinder into contact with both ends...let's also say there is little to no testing or quality control in China for these. Easy to see how intermittent or no contact (or even a short circuit) could happen, yes?
Bottom line is a better, longer lasting and much cheaper alternative exists...an alternative very common today but which would not have been feasible for the consumer market 60+ years ago. A common film capacitor of the proper uF and voltage rating which is high temperature rated. Most condensers (those used for inline 6 cylinder engines, anyway) seem to work fine at .22uF and a voltage rating of 500v would be plenty. A quick look at Digi-Key brought up this one:
https://www.digikey.com/product-detail/en/kemet/R75QN32204000J/399-18311-ND/9449366 There are others, but this one costs about $1.50 and fits most of the needed values perfectly. I'll keep looking for a more high temp capacitor, but I'll tell you up front those are more $$$...and some are larger
Note: it won't look like a typical auto condenser and there is the chance it might have to be mounted outside the distributor (to reduce heat), but I'm certain it would work. And it probably would never need to be replaced.
Here is my question: This capacitor is fine up to 220 degrees F. Your distributor could get hotter than that inside (hopefully not, but it could if you're running your engine on the hot side of things). If it needed to be mounted elsewhere (say over by the voltage regulator or in some other cooler spot) with one wire connected to the points side of your coil and another wire to ground, would this be ok with you? In this application you would have no condenser inside your distributor.
