KJL

I am not sure if I have either. When I check the voltage of the + wire after removing it from the coil, I get 12 volts.

7t2vette

The factory wire is a resistor wire. I just replied to your other post about hooking up a MSD to this wire. The MSD instructions that come with it state that you can do this.

regards

Bruce

mrvette

assuming your car is correct factory that is what you will measure without any loading, now with car running, you should measure about 8-9 volts or so, depending on dwell setting and idle speed, and alternator output....
yes that black lone wire that has a certain springy-ness to it, is actually steel wire in the harness and it's giving correct resistance as part of it's function....another wire goes down to the starter, and will supply a full battery voltage during starting for a temporarily hotter spark....but if that is allowed to remain on the coil + for very long, it will burn up the points/coil...

GENE

john73bb

You will get 12V (or more depending on battery voltage) at the wire when it is disconnected because you need to have current flowing through the resistor to get a voltage drop. Measure the voltage with the wire attached to the coil and the points closed and it should drop a bit. I don't know what to expect, but I would guess it will probably be under 10V.

GaryS

I have a 72 LT1 and the electrical diagram in the GM Chassis Manual doesn't give any differentiation between the LT1 or L48. You can tell if you have a ballast resistor (which you shouldn't have) because it is usually mounted on the firewall and is a white ceramic device about 2 1/2 X 1" doohickey. If you a resistor wire it will be a wire with a white woven sheath on it. I am assuming that this sheath is a heat shield of some sort. On some cars I have seen where this white covering is gone; either worn off, cut off or just plain gone. My resistor wire has very fine print on it and says something to the effect of "resistor" or "resistance wire" or something along those lines. In addition, the one post of the coil has a single connector with two wires going to it. One is the resistor wire, which should give around eight volts during idle, and the other is the starting wire which should give full system voltage, while cranking. I can't send you any photos since my car is in storage.
Gary