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TR3B Coil Issue?

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psutr3

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After removing the heater I tried to start the TR and while it turned over it would not start. While replacing the bolt thru the firewall that held a heater support bracket my “helper” must have brought the wrench into contact with a battery terminal and caused a short. It caused the 3-4 fuse to blow. I replaced the fuse and thought my problem was solved. Not so. That fuse is on the side with the ignition switch and coil. Since it turns over the ignition switch must be ok. After reading some prior posts I tested the coil and from the + post to the - post it reads 3.4 ohms and the HT to + post reads 8770 ohms. From what I’ve read those readings indicate the coil is properly functioning. The coil was installed in about 2010 when I switched to a Pertronix system. It was also changed to negative ground at that time. When I checked the spark with a spark plug tester both from the plug and from the coil HT the spark is more orange than blue which I understand it should be. I also tested a never used coil I purchased at about the time the Pertronix was installed and it tested about 3.1 and 7660 ohms. When I installed it I got the same orangish spark. Do I need a new coil or is there something I’m missing? Any help is appreciated.
Gary
 
I'm sure the coil is OK. I can't imaging damaging it by momentarily shorting the battery. The ignition isn't fused (although PO might have changed that) so a blown fuse won't affect ignition. The fact that the engine cranks does not prove that the ignition switch is OK, but it's unlikely that you zapped it, unless you somehow shorted something on the far side of the switch from the battery.

I'm not sure I understand precisely how you checked the spark. But if you are getting spark at the plugs, the Pertronix and coil and all that should be OK. If the Pertronix is zapped (highly likely after a battery short), it almost certainly won't work at all. I'd check the spark again by holding the plug connector near the block--if you see a spark, you probably haven't damaged the ignition system. If you still think you might have damaged something, the most likely victim is the Pertronix unit. To check it, you could temporarily install points and see if you can start the car.

But it sounds to me like something else. Coincidences do sometimes occur.
 
Sarastro said:
I'm sure the coil is OK. I can't imaging damaging it by momentarily shorting the battery. The ignition isn't fused (although PO might have changed that) so a blown fuse won't affect ignition. The fact that the engine cranks does not prove that the ignition switch is OK, but it's unlikely that you zapped it, unless you somehow shorted something on the far side of the switch from the battery.

I'm not sure I understand precisely how you checked the spark. But if you are getting spark at the plugs, the Pertronix and coil and all that should be OK. If the Pertronix is zapped (highly likely after a battery short), it almost certainly won't work at all. I'd check the spark again by holding the plug connector near the block--if you see a spark, you probably haven't damaged the ignition system. If you still think you might have damaged something, the most likely victim is the Pertronix unit. To check it, you could temporarily install points and see if you can start the car.

But it sounds to me like something else. Coincidences do sometimes occur.
Click to expand...
Sarastro
Thanks for your help. I used a spark plug tester Inserted in between the plug and the lead from the distributor to that plug. I can see see intermittent sparking as “points” opening and closing. That seems to suggest that the Pertronix is functioning. I would think that if it were not functioning there would be no spark at the plug. Should the spark be blue in color ? I’ve read that an orange spark is an indication that the spark is not hot enough. Thanks again for your help.
Gary
 
Hello Gary,
Spark should be blue and have sufficient voltage to jump at least a half inch gap. Test plug lead next to the head, not on rocker cover as any fuel vapor inside might ignite:(. Also, I've had some real problems with pertronix units and now convinced that points are much more reliable.
Rob.
 
This is kinda of shot in the dark, but if you are under the dash and moving stuff around trying to surgically remove a heater, perhaps the amp gauge wire became unhooked. Not sure if this is the case, but without an amp gauge they will not run, and I am not sure if they would crank or not. Just a thought.

steve
 
And thus another petronix thread. When I first read that the battery was shorted I thought that has nothing to do with the not starting. The war-era electrics on this car are pretty robust. But any modern electronics can be susceptible to shorts and sparks.
 
I really can't say anything about those spark testers--I've never used one. I always used the method Rob describes. I will say that if you get any spark at all, the Pertronix is probably OK.

I should add that I'm a little puzzled that shorting the battery at the terminals would blow a fuse. Not impossible, but unlikely. Are you sure that's where the short was, and nothing else is damaged?
 
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