The Stovebolt Site Forums The Shop Area The Electrical Bay Important news about the condenser...

There has been an unexpected development in the Condenser Project. Recently 2 of them failed. And before I go any further, if anybody has any trouble with these, please contact me. I'll send a replacement for you at my expense. My intent has always been these should last a long time and also (more importantly) this project was and still is strictly a non-profit affair with any monies that exceed my expenses going to future work on Stovebolt improvements. If this or any project I initiate loses money, c'est la vie.

What caused this? I can't be certain, however I learned this summer the maker/distributor of the brass I've been using started putting a coating on it (wax based) sometime within the last year (to prevent oxidation and keep it looking "pretty") and we all know brass will oxidize given time, humidity, etc. The coating (or oxidation if that occurs) somewhat reduces the ability of brass to conduct electricity and it is possible this could have caused an intermittent loss of conduction. When I disassembled condensers made in China, I noticed they all had questionable capacitor to ground connections (one reason I believe so many of them fail right out of the box or soon after they're installed). What else might happen? An internal problem in the ignition coil or a failing coil could be the culprit. Also I expect a free-hanging spark plug wire might create the same sort of problem as could other similar ignition problems. Some of that has recently been mentioned and discussed here. And of course we can't rule out a manufacturing defect.

At this point it is important to tell you the capacitor I selected is "self-healing." Most capacitors when fed enough voltage to ruin the dielectric layer will either die instantly or go into a very rapid downward spiral. Some will bulge at the top or sides and I've seen several electrolytic capacitors explode. Mine won't do that. If you feed a self-healing capacitor enough voltage to cause an internal failure, it will first try to repair itself by clearing the damaged area...that being the spot where the dielectric is compromised and the internal short has occurred. In my experience a self-healing capacitor which has suffered a compromised dielectric will restore itself and will be still operating within reasonably acceptable limits (however not like new again)...but only up to a point, naturally. In case anyone is wondering the OEM condensers will fail the same way...the exception being they die right quick.

In the case of the two failed capacitors, one has lost >50% of capacitance (from .22uF to .10uF) and it was one of the very first of these I made. The other one (a newer one) has lost between 14 and 15%, dropping from .22uF to .185uF. The loss of capacitance (not surprisingly) caused the points to fail in both cases. There isn't a wide range of acceptable values. Sun data from the 1950s and 1960s tells me the ideal value is .22uF with a low point of .21uF and an upper limit of .25uF and other sources gave a slightly different lower limit of .20uF...but nothing below that. I can tear the capacitors to bits and look inside, but the damage might be a microscopic dot the size of a grain of sand and even if I find it, I still won't know what caused it.

So here's what I've decided:
1. If a failing coil or some other ignition system problem caused these failures, that's both uncontrollable and in many cases unavoidable. Even if it is a new coil, it could have hidden fatal defects. To my knowledge only one brand of coil is still made in the USA and the Chinese stuff...well, you know what that is.
2. if intermittent connection due to coatings/oxidation/etc is causing problems, that can be remedied. I have now added a solder ring around the part where the attaching screw goes and that should stop any problem with questionable conduction. If you are using one of these and you want to do the same thing, please go ahead. Sand the brass well with fine sandpaper (220 grit or so) and using rosin core solder, make a ring around the screw-hole as you see I've done in the image below. Solder will bond well to the brass (if it is cleaned as I mentioned) and that will prevent it from oxidizing or losing connectivity over time.
3. from this point forward, I'll look into other connection possibilities.

If you have any comments or questions, please let me know.