Technical The condenser, its always the condenser

Wish this thread was available 3 weeks ago when I was fighting an intermittent spark issue. Fought it for nearly a month. I finally opened the points manually with the key ON to check for spark and it looked like an arc welder around the cam plate. I changed the condenser and now have power and a slight yellow spark when I open the points. And the bad condenser was a new Delco piece. The one I installed is probably 30 years old. Also, the wire on the new one is just barely long enough to reach the points. I may have damaged the internal connection pulling on it.

 

Should have mentioned on your earlier post.....on my long trips I have been know to pack most small parts as well as a starter and a alternator. Most of time didn't need it but those 300 miles plus was a shake down for my builds. Broke down plenty close to home in my 64 Chevy...and like was said - rarely changed that darn condenser. Glad your a going !

 

Help me out here. Previous post said they had good spark across points. As I recall, if condenser is good, you shouldn't get a spark when the points open.

 

I was using a screw driver to open the points. Several times there was no spark and occasionally a very slight one which may have been partially due to the screw driver tip grounding out. Either way I won't question it as it has been running well for a week now. That help?

 

I was hoping someone would respond to my question. Back around 1964-65 I had a problem with my cars ignition breaking up at higher rpm. Drove me crazy. Changed points several times, even put in a set of Mallory points. No change. I was 19 ish at the time and my buddies Dad, who was very old (maybe 50) asked if I changed condenser? Why would I change condenser? They don't go bad. Well, I did change the condenser and that solved the problem.

 

ain't that something? I remember when the saying was " if the points don't show too much metal transfer, just reuse the old condenser."

 

I hope this thread helps the next guy. I had good hot spark at the points, no fire at the sparkplugs. The only thing I changed was the condenser and now its running.

 

What was your question?

 

All the air cooled VW’s used Bosch condensers. Even though they are the same as the Porsche units, I bet their a lot cheaper. Condenser problems can drive you nuts. Years ago, I was a line mechanic at a VW shop. I had a car that had a miss from #2 cylinder. I checked the valve adjustment, ran a compression check, the spark plug, the , cap and the wire and resistor. All good. I took the wire from #1 with #2. Same dead cylinder. Any way, out of desperation, I changed the condenser. Problem solved. That damn condenser would pick #2 and misfire every damn time! Later on in my career, it happened on another car. I found the problem a LOT faster that go-round.


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That may be why I could get strobe on my timing light on every spark plug wire except number one

 

This is one of those situations where an ignition scope would prove useful. I picked one up just for grins and while I'm not very good at interpreting the waveforms there is definitely something hinky with one cylinder on my Y-Block, has a big spike in the firing voltage. Bad plug wire probably, or maybe plug. Defective condenser or contact points will also quickly be revealed, if someone knows what they are looking at anyway.

 

See post #33

 

I would think that if there was no arcing the points would never need to be replaced. I always thought some was normal.

 

There is no question in post 33 but I responded in post 37, telling you that my condenser was bad but I had good hot spark at the points

 

A condenser (or capacitor, interchangeable terms) charges when the points open, and discharges when they close. When a capacitor charges, there is an initial inrush of current, which tails off as the capacitor becomes charged. In a points ignition system, when the points close the coil primary is energized and creates a magnetic field around the coil's iron core. When the points open the magnetic field collapses and creates a high voltage in the secondary of the coil, which is then "distributed" to the appropriate spark plug. At the same time, a fairly high voltage is created in the primary windings of the coil, which needs to find a ground somehow in order to discharge. At the instant the points open the voltage spike in the primary windings begin to charge the condenser. When a condenser isn't doing it's job, is weak, etc. this voltage arcs across the points to bleed off rather than charging the condenser. In a properly functioning points ignition system the points do spark a bit, but not nearly like they do when a condenser is bad.

 

The mechanic I learned from told me he did not change the condenser on his car but did on customers
as he did not want to deal with an upset customer who had one fail just after a tuneup. He did carry a spare in the glovebox. I saw an occasional failure in one back then, but it seems they are a lot worst now.

 

Probably get get flamed again, but this is why I wen to Pertronix ignition a long time ago on all my cars. Even on my 1953 ford naa tractor. No problems ever, just saying.

 

The big problem seems to be many if not most distributors in vintage iron are excessively worn and points don't like that at all, it is about impossible to achieve a steady dwell. But, a good serviceable distributor coupled with quality ignition parts the tune-up will remain satisfactory for a very long time, years and years. Most people don't use these for daily drivers anymore.