From: rumbleseat (Original Message) Sent: 3/24/2002
Something I change when installing a Mallory point type dist on a 59 AB engine. Mallory mounts their condenser directly on the bottom of the front mounted distributor... right behind the front pulley. This is impossible to replace without pulling the distributor and is a hot spot. The heat will shorten the life of a condenser drastically. Naturally it will only fail after it's been driven and the engine is hot. Guess what.... .burnt and fried hands taking the distributor off and on. The 59AB engine mounts their coil away from this hot spot..... near the front of the intake manifold in the path of the relative cool inrushing air from the radiator and fan. I relocate the condenser from the distributor up to the coil which permits me to change condensers in minutes without frying my hands. Simply splice a longer wire from the distributor to the distributor terminal of the coil. Most condensers have a slip-type collar around them which I redrill and bolt to the coil mounting bracket. When I have to change I unscrew the mounting screw about two turns and slip the condenser out and slip a new one in. I've also done this to stock 59AB distributors since the condensers being sold today for these are poor. The increased length of the wire will not affect the rating of the condenser appreciably..... rumble seat
From: bobH Sent: 3/25/2002 12:23 PM
Re: Rumbleseat's comment about 59A-B condensers.... In the last couple years, I've been telling the parts-counter-guy, a condenser for a 53 or 54 Chevy. The Chevy condensers seem to be a lot easier to buy, and I haven't had a lick of trouble with them. As far as I can tell, they work perfectly for the Ford application on a stock-distributor, 59A. I like the idea of moving it up 'top-side' - I'll do that next time around. Thanks. bobH
From: Roger/Sacramento Sent: 3/25/2002 4:00 PM
The box has been opened now and my interest is peaked. Could we have a clinic here to enlighten those of us that are ignorant of these things.
I would like to know what the criteria is for a condenser?
Are there quality items to pick from?
Can one use just any old condenser?
I will be using a stock crab distributor.
What is the best condenser to use regardless of cost?
From: bobH Sent: 3/27/2002 7:17 PM
Roger, I'm surprised no one else took a shot at your questions. 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
From: rumbleseat Sent: 3/28/2002 5:11 PM
Roger/Sacremento: Suggest you check out Bill B's techno site. Click on http://www.btc-bci.com/~billben/flathead.htm There's a lot of super information on this site about all facets of flatheads. In there I wrote about condenser problems I was having serveral years ago and eventually traced them to the condenser. Seems the only condenser being made for the 59AB distributor at the time were made in Argentina. I would go through one every couple of hundred miles or so. They were stamped Argentina in EXTREMELY faint letters on the shell. Seems odd, but USA made condensers were available for 37-41 and 49-53, but nothing for the 42-48 distributors! Since I was running a stock dist. at the time, I wanted to keep it as stock appearing as I could, so was running these funky Argentia units. I checked the rating of these and found they were all about 0.23-0.24 mf (microfarads). Having on-going problems I went to an Petronix electronic distributor and found them to fail quickly (8 in one year and the last one I used lasted less than 10 miles..... it failed at midnight when it was blowing cold and 10 degrees and on a steep up hill!). I had purchased 2 complete Petronix distributors after having problems on a run when I was several states from home in a driving rain storm. After this electronic fiasco, I purchased a Mallory dual point and have never had a moment trouble except for the on-going condenser problem. The Mallory condensers failed almost as fast as the ones from Argentia on a stock dist. These were all checked and were found to have a rating of 0.24mf. A call to Mallory tech revealed they knew about the problem, but were powerless to correct it since the EPA had made them change from an electrolysis treatment on the shell to a spray-on type shell covering. These spray-on type condensers seemed to fail faster when they were exposed to hot temperatures. I suggested a longer pigtail so I could locate it on the front of the intake manifold mounted coil so it was in the path of radiator air. The tech said the rating of the condenser would increase slightly, but there shouldn't be any problem. Tried it and it worked. He also told me to use a condenser with a higher mf rating.... something around 0.35mf if I could find one. He said one for a dist for a 1983 MoPar 318 (383?) V8 was the closest thing he could find. These check out to be about 34mf on my tester. Then I found an old timey brass Mallory condenser and I use it. The spark it stronger with it. Hope this helps...... rumble seat.
From: AlbuqF-1 Sent: 3/28/2002 7:14 PM
I think the polarity of the condenser does matter. It has been my understanding from British motorcycles (which were all positive "earth") that when converting to negative ground you have to change to condensers from an American car or bike. The Lucas condensers are all marked "+" on the grounding side. I believe automotive condensers are "electrolytic" condensers, which are polarity sensitive and marked accordingly. Would be nice to know if this is fact or not.
From: JWL Sent: 3/28/2002 10:20 PM
It may depend on the construction of the condensor, but I would generally say they are not polarity sensitive. There is no electrical circuit in a condensor (unless it is useless) and one side is repeatedly positively charged and the other side negatively charged while in operation. Many stock Ford 6V (pos. grnd.) have been changed to 12V neg. grnd. without causing a problem.
From: bobH Sent: 3/29/2002 2:15 PM
Suggestion for Ross, or anyone that is interested.... Very carefully 'dissect' an automotive condenser. (This is something we did in that tune up class I mentioned.) I believe you will be able to convince yourself about 'polarity-sensitive'. I don't know if they are all constructed the same, but the one that I looked at, had nothing in it to make it polarity sensitive. As JWL indicated, there are 'jillions' of vehicles that have been switched from pos to neg 'earth', and I've never heard of anyone having a condenser problem due to the change.
And, yes, I DO understand the 'polarity-sensitive-issue', if one is dealing with general electronic circuits, and capacitors that are intended for such.
Which leads me to another soap box.... I've been trained to acknowledge these devices as 'capacitors'. But, I believe the 'automotive-world' will ALWAYS call them condensers. Go to an automotive parts house and ask for a capacitor, and you will likely receive a blank stare. Go to an electronics store, ask for a condenser, and you might get an explanation that a condenser converts vapor to liquid. They are often found in steam systems and air conditioners, but not in electronic circuits. Enough....