No Spark

[fiasco]

Finally got back to the forum after several weeks away, and what happens today? The Fiasco quits with the whole family inside - out joyriding for the holiday and looking at houses we could never afford to buy.

Plenty of juice from the battery - starter turns over fine - poured a little fuel into the carb to be sure. Bottom line - no spark.

Poked around a bit - replaced the coil with new, then called Alvon (Ventura Ace). Under his direction I traced all the wires, tested various connections, set the gap on the points (width of the cardboard in a matchbook ). Looked for shorts, took everything apart and put everything back together several times. No luck. Getting power to the coil. Getting power on the wires to the points/condensers.

Finally got hold of a timing light and put it on the big wire between distributor and coil - nothing. Am I right in thinking we should have gotten a response from the timing light? Since we didn't, I am thinking that means no spark from the coil to the distributor, thus no spark to the plugs. Checked the wire for continuity, and it got a good reading on the meter.

Checked and double checked all connections. All plug wires are relatively new - replaced with the engine a couple months ago. Points and condensers were not replaced at that time.

Thoughts?

Thanks,
-- se

[ventura ace]

When we talked on the phone, it seemed to me that everthing was good but the condensor (it was acting as if the condensor was shorting out to ground). Did you get a chance to change the condensor?

Here is a copy of some good discussion regarding condensers that I found on the internet:
So, let me see if I can make myself look foolish. First, I would suggest looking at an old Motor Manual, if you have access to one. I believe some of them explain the function of the condenser. The condenser is present to absorb the 'spike' or 'pulse' that occurs when the points open (and the coil fires). This is because current is flowing when the points are closed, and while the coil is 'saturating'. When the points open, the current is still trying to flow. The condenser trys to absorb this. I'm looking at a MM for 35 to 46, and see a picture of 'point-degradation' (material transfer from one contact to the other), for both 'over' capacity, and 'under' capacity condensers. The pitting and 'tit' formation that occurs at the points is a result of 'over', or 'under' capacity. From the MM pictures, 'over' capacity results in the 'tit' pointing in the 'plus' direction. And, 'under' capacity leads to the 'tit' pointing in the 'negative' direction. Ideally, condenser capacity would be selected so that there is no tit pointing in either direction, and all that is seen at the points is a 'burning' that erodes the contacts away, from both surfaces, equally. Indeed, this is the result that is most often seen on well-used points.
The value for condenser capacity is not cast in stone. It can be different for different people, depending on how they use their engine. And, not all condensers are made with precision. They vary from unit-to-unit. So, when you buy a new condenser, it is not necessarily going to be exactly the same as the last one. (Side note here... An instructor, in a tune up class, maybe 45 years ago, advocated, if you are doing a tune-up, and the point wear on the old points is 'even', then DON'T change the condenser. His theory was that a condenser had been found that suited the particular driving style. I don't necessarily subscribe to this theory. I have occassionally seen condensers fail. So, I usually replace them, unless I'm working on my own car.) I HAVE experienced a condenser failure on my own car. The symptoms were, at first, intermittent 'sputtering', or misfires. As it progressed, it got to the condition where the vehicle did not want to run at all. It would start and immediately die.
You can find 'average' values for most automotive condensers in many old MM's. Condenser capacity (or value) varies a little from one make to another (but not by much).
In automotive applications, 'neg', or 'pos' does not matter. (Don't try to carry this thought over to TV sets, or other electronic application. Many of these ARE polarity-sensitive.)
So, to try and answer one of the questions, yes, almost any condenser can work. Some better than others. I wouldn't recommend taking a condenser from, say, the alternator (or generator, or regulator), and attempting to use it for an ignition. In general, I would expect the 'value' to be a little too far off to be useful for the ignition. But, to interchange ignition condensers between makes, like GM or Mopar on a Ford, it should work. A little running time will tell if the 'value' is satisfactory. As I've indicated in another post, I am using 53-54 Chevy condensers with a crab-distributor on my flathead. The polarity difference is no concern, and my point-wear-factor has been satisfactory. Next time around, I will move the condenser close to the coil (as Rumbleseat suggested). This will lengthen the effective lead-wire (to the points). Theoretically, that will slightly increase the condenser value, but I do not expect to see any real-world difference.
Criteria -- the one that keeps the points from pitting.
Quality -- I don't know. In general, I prefer to stay with 'major' brands. But, for me, it's a shot in the dark.
Any old condenser? -- yes, as long as it's value is ok for ignition systems. Note: when a coil is changed, and the average current through the points changes, this indicates the need for a condenser 'value' change. Probably not a 'real' concern.
Best, regardless of cost? -- I haven't a clue. I would say the one that works is the best. This might lead me to one of those 'funky' brass Mallory condensers that was mentioned here a few days ago, if I stumbled on to one, and if it was still functional. As with many electrical 'things', trial-and-error sometimes takes priority over solid engineering.
Some of this is just opinion. I'm always interested in other views. bobH

[fiasco]

Thanks Alvon. I'm going to try to get the condensers changed tomorrow - just couldn't get to it today.

Thanks for your help today. Look for another call if the new condensers don't do the trick.

-- se

[fiasco]

Two new condensers and the Fiasco is running like a jet again. Now back to the cosmetic work...

-- se

[launieg]

Glad to see you've resolved this Steve. The other day I discovered my car was dying under heavy electrical load (like when the fan went on) and was chagrined to discover that it was only that the connections on the coil were not tight (having converted to a duraspark coil last fall). Sometimes it is the simplest thing, and after I checked fuel pressure and everything else too!

I hope you don't mind Steve, but I"m going to steal your topic at this point, because it is a related matter.

I read what you posted about condensers Alvon, but it raises the question of the value of a condenser located on the coil with electronic ignition (I have an '81 fuel injected). I can't see the need for this condenser in this case, but I think I remember that a little while back Ron felt it must still be used. (Sorry if I'm mistaken Ron.)

I don't have mine connected and it seems fine. I always thought that the condenser on the coil on the FI models was only to suppress coil noise to improve car radio quality. We used to to that (add condensers) to our cars back in the early '70s, when we were getting into cassette decks. It worked!

So what is the concensus (or varied opinions) on this? I understand that the condenser on a "points" dizzy is to prevent arcing across the points, but is there a need for the one on the coil in an electronic ignition dizzy?

[kmead]

On an electronic ignition car the condenser is there to absorb the spike that sends a pulse of noise back into the electrical supply and can cause noise in your car stereo. This is evidenced by a ticking sound in your stereo that will vary with engine speed. There will also sometimes be one on the alternator as well for the same reason though the noise will be a whine and can indicate an issue with your diodes.

Karl