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That pink wire and a missing 2 Volts

hbar

Member
Hi, first post on this forum. I've attempted to do my homework elsewhere with no luck. I just replaced my distributor & coil with a Pertronix II dizzy & Flame Thrower coil. It's all working, yay, and the car is running better than it ever has. I'm just really confused about a few things, and I'm hoping somebody here can explain why I saw, and what I am still seeing.

I initially attempted to splice into the pink wire near the ignition, and again near the firewall with a 12ga. wire to effectively bypass the resistance wire. Ohms Law suggests there would be virtually no current in the pink wire, and 100% in my new yellow wire. Perhaps I gave up too easily, but I decided there was no way I was splicing into the pink wire at the firewall, so I ran my new wire through the firewall and to the (+) side of the NEW coil. I left the existing lead connected as well, which shouldn't make a difference. Per the Pertronix instructions, I turned the key to ON and measured the voltage at the coil to be 10V. I was expecting 12V. When I went to turn the key off (it had only been 30-45 seconds), there was that terrible smell of electrical fire, and a hint of smoke. The 3" of insulated pink wire between the ignition and my splice were freaking hot. My little infrared temp sensor is out of batteries, so I don't know how hot, nor do I know how hot it gets normally. But I know I've never smelled that before. Since I only saw 10V at the coil, the other 2V must have been in the wire I thought I was splicing around. P=IV, and P was clearly significant, which means that there was current in that pink wire still. How is that possible??

So my next move was to completely eliminate pinkie, which I did. Disconnected from the coil, cut out at the ignition (I left the wire connected to the firewall plug, so rolling back will forever be an option). Turning to ON & measuring, I get the full 12V at the coil. However, once the new dizzy is on, and all the wires are hooked up to the dizzy & coil, I only see 10V again. So where the crap are the other 2V? Aside from the 3" of black/red wire just off the ignition, all the wires are brand new, and there are no splices other than the one at the ignition. There should be virtually no voltage drop in this portion of the circuit.

Please, help me understand.
 
You're on the right track...the pink resistor wire does get hot, even with a short stub. If you had checked the other side of the pink wire, it should have been cold. It doesn't get hot enough to smell, though, unless you're pulling excessive current through the system and burning up the normal wire.

So...now you're getting a full 12V to the coil, but when you hook everything up, you only get 10V? Do you get the smell still? I'll bet the loss of voltage is something related to what you hook up to the dizzy, and there is a good short somewhere.
 
Thanks for the reply.

Well, NOW I'm only seeing 10V at the coil. When I measured 12V, there was a wire I hadn't hooked up yet, and I'm not sure why I'm only thinking of it now. There was a wire which went from the (-) side of the coil back to the carb, into the vicinity of the vacuum take-off (I have a Holley 600cfm, btw). I don't know exactly where, because I'm only just thinking of it now. It might not even go to the carb; I'm sure it goes to ground, though. How sure? Well, given that I'm missing 2V, not very! The smell is gone, and the car runs fine. The Pertonix has 2 wires, so I'm wondering if this "legacy wire" on the (-) side of the coil isn't necessary. Is the black wire on the new distributor the ground, or is it looking for the ground?

The pink wire (and now, my new yellow wire) are only in the circuit at startup, is that correct? With pinkie out and the key turned ON, there was no smell, and no heat off the new wire. Not surprising, given that the new wire is R ~= 0, and P=(I^2)R. Could be a crapton of current, though, but that's tougher to measure.

I realized that the other part of the splice probably wasn't hot, but it wasn't until after I had already removed it from the circuit. It still shouldn't have caused a smell. So since that was a new symptom, and the only thing new to the system at that point was the coil, can you help me understand what's going on in the coil when the key is turned on (but not actually starting the car)?
 
Sounds like your extra wire going towards the carb is for an electric choke......That can be run to the stator output of the alternator.
 
Ok, I'll check to make sure that wire is connected cleanly to the carb, pending actually moving it to the alternator. But I guess that leads me to another set of questions. IF the automatic choke is connected to the alternator, then I guess I would need another wire from the (-) side of the coil to engine ground? Which is related to my question from above, is the black wire on the new distributor at ground potential, or does it need to be connected to an engine ground?

I've got to find those 2V. It should be pretty simple, since this part of the system is very much isolated now. Maybe I just need a few hints on where to check.
 
If that is the pertronix black wire you are referring to, the directions should show what to do. Nothing on the coil goes to ground as far as I know.


Also, what is the voltage at the battery when you have 10 volts at the coil?
 
"AzPete" said:
If that is the pertronix black wire you are referring to, the directions should show what to do. Nothing on the coil goes to ground as far as I know.
It goes to the coil, but it doesn't answer my more fundamental question, which I'm only asking so that I understand. Following the directions is simple...understanding the WHY of each step is not always so easy.

"AzPete" said:
Also, what is the voltage at the battery when you have 10 volts at the coil?
12V. Naturally, since you've asked, I'll have to check again tonight.
 
Power for the coil comes from the ign. switch. With a stock coil, this power passes thru the coil to the points. They open, causing the higher power to be supplied to the spark plugs. (short version)

For the pertronox, I would say the reason that two wires run to the dist. is one wire provides power for the pickup to function. The pick up does the same function as the points, but must need a power source to do that. The power coming from the ign. switch should pass to the dist. also.

I believe this is what you are asking......
 
The - side of the coil goes to a small lead from the distributor, which in turn, is connected to the points. The true ground of the system is the engine block via the distributor.
 
"hbar" said:
Naturally, since you've asked, I'll have to check again tonight.

Well I checked again, and I'm seeing 12V, although I didn't follow the instructions verbatim. Pertronix says to jump the - side of the coil to ground, which I didn't do just now. The only wire on the - side of the coil is the black wire off the new distributor. Also, I was wrong earlier, the wire from the carb does go to the alternator. According to Midlife's last post, I don't think that jumper to ground should make a difference.
 
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