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TR2/3/3A Dead Petronix and rough running.....

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K

karls59tr

Obi Wan
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I must have left the key on which seems to be a common occurance that fries the Petronix because I wasn't getting any spark to the plugs. Anyway I swapped in a plate with new points(.015") and condensor. The motor started but was running rougher than I remember it as this was the first start of the season.
Qestions:
1.On a coil marked "+" and "-"....SW= "+ " and CB= " -" Correct?....dyslexia strikes and POS ground car.

2. Do I need to adjust the Distributor a bit after swapping in the points plate?

3. The Red ignition light stays on now.....do I have to Polarize the generator now that I've been mucking around with the wiring?

4. Anything else that I may have overlooked when doing the swap?

Any help appreciated.
 
1. With a coil marked "+" and "-", it might be easier to just observe the polarity markings. Since your car is positive ground, and the points are grounded, then the "+" terminal goes to the points. This would have been the "CB" terminal on an original coil.

2. Almost certainly. Mine triggered almost 10 degrees away from where the points did. Doesn't seem like that should happen, but it did.

3. Normally, mucking about with the wiring wouldn't require repolarizing. But it can't hurt to try.

BTW, there is a new, improved version of the Pertronix that supposedly doesn't self-destruct if you leave the key on. If you want to go back to electronic, you might check out the "Ignitor II". However, I'm not certain it is available in positive ground. Their catalog seems to imply that it is, but I couldn't find anyone that sells them.
 
Check your needle screws that pierice the plug wires. The last time I had my Petronics go out it was running rough found that two cylinders int firing intermittently. Found the piericeing screws were brunt going in the wires. Replaced cap, wires and reinstalled points. Have not had any more problems.

don
 
So once the motor is idling I loosen the dist hold down clamp and move the dist a little either way until I gate a steady idle?
 
I'd suggest using a timing light instead, especially since timing may not be the issue (as don said). Also, it's easier to make small adjustments with the thumbwheel, rather than the clamp.

I've had the same problem with the piercing screws, but only when trying to use carbon core wire. IMO carbon core is simply not compatible with the stock TR3 cap. Either use solid core wire (as original and as I do), or switch to a cap with push-in terminals.
 
I can see how the screw could miss the carbon carbon fibre as it is so thin. I've got the solid core bumble bee wires but they are old and could probably use replacing.
I had a bad experience last year when using a different set of plug wires and the push -in terminal cap. The car ran great for months and then died before I was about to go on a long trip. It seems that the cap, that was supposedly for the TR3, was actually not as tall as it should have been so that the carbon rod and it's bakelite tower wore away against the rotor till the carbon wore away almost completly along with a good chunk of the bakelight:frown-new:. I would drive about two blocks and the car would die. Something to look out for if trying a push-in cap. Not a bad idea to carry a spare dist cap in the boot as well.:encouragement:
 
Does Pertronix acknowledge and warn against the problem of leaving the ignition turned on?

How long is "too long" when leaving the ignition on with Pertronix?

Also, what is the difference between solid core plug wires and others? How do you recognize the difference?

thx
 
A friend of mine left the key on in his A-Healey for about an hour. The car would not start. The result was the coil was red hot and the small wire inside the distributor got totally fried.
So even if you do not have electronic ignition leaving the key on can ruin your day.
Charley
 
I'm so leery of all the talk of how great an electronic ignition is, then to read of these experiences. Being a worrier, isn't the next natural sequence of a red hot coil a nice fire in the engine compartment?
 
There was a previous thread here a month or so ago that discussed the experiences with electronic ignition. For all the bad things about them at that time killing the unit by leaving the key on was not brought up. Maybe I was not clear in my earlier message. The Austin -Healey was a regular ignition system. So leaving the key on can damage ANY system.
Charley
 
KVH said:
Does Pertronix acknowledge and warn against the problem of leaving the ignition turned on?
Click to expand...
Yes. There are warnings in both the installation and the troubleshooting instructions (although they imply that the coil would fail first).
How long is "too long" when leaving the ignition on with Pertronix?
Click to expand...
One of the warnings says to never leave the key on with the engine not running for more than 30 seconds, but that is "during this test".
https://www.pertronix.com/support/tips/
I don't know of any other statement from Pertronix.

But, both the coil and the Pertronix unit will be dissipating roughly twice as much power as they are designed for; and heat is the enemy of all electronics. Even if it doesn't fail immediately, overheating the module can shorten it's life.

Of course, if you do need to leave the key on (while troubleshooting an electrical problem perhaps), then just pull one of the low tension wires off the coil. Or, check the ammeter and turn the engine until the virtual points are open (no current draw shown).

Also, what is the difference between solid core plug wires and others? How do you recognize the difference?
Click to expand...
Look at the cut end of the wire. "Carbon core" is actually strands of fiberglass impregnated with carbon, and is definitely black. Solid cores will be either copper or silver colored.

In my case, the points appeared to make good contact with the core initially, but the carbon would burn away around the point. I was using a MSD ignition at the time, so no doubt the higher spark energy played a role in burning out the carbon (it also eventually burned out the carbon button in the cap); but my feeling is that it demonstrated an easily-avoidable weak point. I have seen carbon core wires fail in similar fashion on engines using just points and a Lucas Sport coil.

I'll add that I feel it is good practice to check the resistance of the plug wires at each major tune-up.
 
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