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TR2/3/3A TR3A Coil/condenser problem

RA6263

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I finished a restoration 6 years ago, rebuilt engine and replaced stock coil with a Lucas Sport Coil. Running fine but condenser failure 2 years ago. New condenser, all is OK until this weekend. On way home on a 400 mile trip, I experienced strong misfire climbing a hill at full throttle. Backed off and was OK. Drove car yesterday and misfire under load again. Question: Can the coil cause a condenser failure? Also, would you suspect the coil or the condenser for the misfire? Thanks.
Mike
 

TR3Nut

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I finished a restoration 6 years ago, rebuilt engine and replaced stock coil with a Lucas Sport Coil. Running fine but condenser failure 2 years ago. New condenser, all is OK until this weekend. On way home on a 400 mile trip, I experienced strong misfire climbing a hill at full throttle. Backed off and was OK. Drove car yesterday and misfire under load again. Question: Can the coil cause a condenser failure? Also, would you suspect the coil or the condenser for the misfire? Thanks.
Mike
It does act like an ignition problem. I installed a Crane XR 700 electronic ignite system in 1972 and the only problem I have was the cap went bad one time, the coil wire failed one time. The only item on the distributor is the photo eye, the rest is in a remote mounted heat sink that contains the micro chips, etc. I now have close to 100,000 miles on the car. Best move I ever made
 

CJD

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Condensers are matched to the coil current, so in a way they could cause the condenser to fail. I think the culprit, though, is the poor quality of condensers we are being sold lately. There have been at least a couple threads on this topic.
 

TR3Nut

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Condensers are matched to the coil current, so in a way they could cause the condenser to fail. I think the culprit, though, is the poor quality of condensers we are being sold lately. There have been at least a couple threads on this topic.
What you say is quite true. Quality control and not so good materials used are the problem and that is why I went to electronic ignition. I take at least one trip every year that can be from 2,000 to 5,00 miles and don’t have to worry about coil or condenser failure
 

2liter4cyl

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On a good authority, the value of the condenser should be between 0.20 mfd and 0.24 mfd. You can buy for little money a tester, or someone who has a tester may help. A low value will cause build-up on the plus side while too large a value will cause build-up on the minus side of the points.
 

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charleyf

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I finished a restoration 6 years ago, rebuilt engine and replaced stock coil with a Lucas Sport Coil. Running fine but condenser failure 2 years ago. New condenser, all is OK until this weekend. On way home on a 400 mile trip, I experienced strong misfire climbing a hill at full throttle. Backed off and was OK. Drove car yesterday and misfire under load again. Question: Can the coil cause a condenser failure? Also, would you suspect the coil or the condenser for the misfire? Thanks.
Mike
My experience between a coil and a condenser failure says yours was a coil failure. My two coil failures both were similar to what happened to you. My one condenser failure cut out twice in about that many minutes and then totally died. The coils misfired but kept working just poorly. Then it totally died .
Charley
 

Sarastro

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I looked into this some time ago, and it is pretty clear that the poor fabrication quality allows the capacitors to burn internally, increasing the internal resistance. The best options are (1) get one from one of the better manufacturers, like Bosch, if you can find one that fits; (2) replace the usual one with a polypropylene industrial capacitor, which is readily available from Digi-Key or some similar electronics supplier. I use 0.22 microfarads, and about 400 volts is enough; higher voltage is OK. The latter will require a little work mounting it in some way and connecting wires to it.

By the way, I've read that story several times about the capacitor changing value and determining whether it's high or low from the way the points burn, and I can't for the life of me imagine any way that could be valid. I'm VERY surprised to see it in some Toyota service literature. In any case, the value of the capacitance really can't change--it's just a roll of foil wrapped up with some plastic, probably mylar. The electrical properties of the materials won't change, and the size of course won't either. When a capacitance meter shows a change, it's probably being upset by the increased series resistance.
 

Sarastro

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sp53

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I remember my high school electronics teacher saying the condenser absorbs static electrons from the coil and that the condenser and coil have the important relationship. He said this because the auto parts stores liked to sell points and condenser and felt that was nonsense to replace the condenser each time the points where replace . He also taught that the pitting and dimpling of points was cause by the coil or condenser. What side of the points had the dimple or pit indicated where the problem was the coil or the condenser, but I forgot which was which. it does sound like a fuel problem

steve
 

Frank Canale

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Interesting option, I am a tinkerer and don’t mind adjusting points but that system also adjust dwell real time and seems to work very well on your car.
 

charleyf

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When I rebuilt one of my TR4's in 2011, I installed an Accuspark electronic distributor.
Worked great for a year and then when I was on a trip of about 250 miles from home--it died. Just flat died. I was able to get it towed the rest of the way to where I was going (Triumphest). There I was able to scrounge another distributor and set it up and was able to drive home. I replaced it with a points distributor and have kept it that way since. I was offered a new module to replace the one that died as the unit was still under warranty.
I would note that since then I have seen hints that having solid core plug wires messes with the electronic ignition. I had changed to the solid copper wires prior to the unit failure. Still do not know the truth of the solid core wires. I never saw anything in the directions about the plug wires.
Charley
 

Andrew Mace

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I remember my high school electronics teacher saying the condenser absorbs static electrons from the coil and that the condenser and coil have the important relationship. He said this because the auto parts stores liked to sell points and condenser and felt that was nonsense to replace the condenser each time the points where replace ...
^^^^^^
This! :smile:

Also, I seldom if ever threw out old rotors and condensers when replacing same. Because of that, I've rescued myself and friends on several occasions when it was determined that a: a new part failed and b: the old one I had kicking around in the glovebox or home on the workbench still worked just fine! (Some years ago, there was -- and might still be for all I know -- a huge run of really terrible and poorly made rotors as well as condensers; that's when I started carrying the used bits in the glovebox rather then just piling them up on the workbench!)
 

TR3Nut

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When I rebuilt one of my TR4's in 2011, I installed an Accuspark electronic distributor.
Worked great for a year and then when I was on a trip of about 250 miles from home--it died. Just flat died. I was able to get it towed the rest of the way to where I was going (Triumphest). There I was able to scrounge another distributor and set it up and was able to drive home. I replaced it with a points distributor and have kept it that way since. I was offered a new module to replace the one that died as the unit was still under warranty.
I would note that since then I have seen hints that having solid core plug wires messes with the electronic ignition. I had changed to the solid copper wires prior to the unit failure. Still do not know the truth of the solid core wires. I never saw anything in the directions about the plug wires.
Charley
Petronics and other electronic ignition systems have everything in the distributor where the X-RAY 700 has only the pickup eye in the distributor, the rest is in a heat sink mounted away from the engine so its electronics stay cool. If you have a Petronics or similar system, carry a distributor plate that has a set of points and condenser already mounted when yours fails. 51 years and no problems with the XR700
 

charleyf

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Petronics and other electronic ignition systems have everything in the distributor where the X-RAY 700 has only the pickup eye in the distributor, the rest is in a heat sink mounted away from the engine so its electronics stay cool. If you have a Petronics or similar system, carry a distributor plate that has a set of points and condenser already mounted when yours fails. 51 years and no problems with the XR700
My unfortunate problem was in having a Accuspark distributor. Not a regular Lucas distributor that I could change the plate and put a set of points in it. My only option would have been to carry an extra electronic module for the distributor.
Charley
 

Sarastro

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I remember my high school electronics teacher saying the condenser absorbs static electrons from the coil and that the condenser and coil have the important relationship. He said this because the auto parts stores liked to sell points and condenser and felt that was nonsense to replace the condenser each time the points where replace . He also taught that the pitting and dimpling of points was cause by the coil or condenser. What side of the points had the dimple or pit indicated where the problem was the coil or the condenser, but I forgot which was which. it does sound like a fuel problem

steve
Well, if the guy thinks that the "condensor absorbs static electrons..." I'm not quite ready to accept him as an expert.

I do kinda understand the idea that there is no need to replace the capacitor. The repeated reports of capacitor failure in Kettering (i.e. conventional) ignition systems puzzled me at first. I'm sitting here in my office cum electronics lab, and I must have tens of thousands of capacitors within a few feet of me, and they almost never fail. So, why do automotive ones fail so often? That's why I undertook the study, and it was eye-opening. I wrote it up at http://sprite.nonlintec.com/cap_failure/

I think this is yet another example of manufacturers "losing the formula" when they try to reproduce something from the past. It happens a lot. There really was no need, in the days when our cars were new, to replace ignition capacitors at every tune up, as they were made right, but I think it would have been dangerous to try to use one forever. The kind of deterioration I identified probably was happening back in the day, just slower.
 

TFB

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After a recommendation from this forum I went with a blue condenser from British Vacuum unit in NH,USA
Check out the web site for some interesting info.
Tom
 

TR3Nut

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After a recommendation from this forum I went with a blue condenser from British Vacuum unit in NH,USA
Check out the web site for some interesting info.
Tom
If you decide later to go with an electronic ignition system, Comp Cams in Tennessee carries the Xr-700 . They also have the proper coil and ballast resistor. I also moved the coil from the engine and mounted it on a heat sink holder I made on the left inner fender. Coil stays nice and cool.
 
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