Okay, Something's funny here. It appears that there is a resistor wire for the coil. I assume That I should see 6 volts at the underhood connector, but I see 12. Was the resistor wire the one on the engine harness or has the P.O. made a mod?
I'm assuming you are looking at the coil + voltage with everything connected. If so you should see a reduction in voltage of 4-6 volts. If you disconnect the wire and measure the voltage it should be around 12V (or close to whatever your battery is).
If in fact it's hooked up and you're still seeing 12V then something is wrong. In '70 the resistance is in the loom and is not a separate resistor.
And one more tidbit, the *other* wire that's on your solenoid? ...there are 2 small wires... is for bypassing the resistance during start so that the coil will get enough current to start the engine.
Well, I run a blaster 2 coil and an MSD box, so the wire from the coil + to the firewall connector is not there anymore. Was that the resistance portion of the wire? or do I have to pull a certain amount of power through it to get the drop. I had used it as the "turn on" wire for the MSD box with no problems. I was going to also use it to turn on my GM alternator also and possibly run the electric choke on my edelbrock carb, though It may be easier to run it right off the alternator output, though I don't feel quite right about that for some reason.
The resistance is actually in the portion from the dash to the connector under the firewall. And yes you have to pull a load on the wire to see the drop: ohm's law. If you are using the wire just to "enable" the MSD box then the drop is negligible and you won't see much.
If you have a wire from the battery to the coil and and you need resistance then put it in series with the wire to the coil. I would double check with MSD on the proper config as I don't have access to their wiring diagrams.
I don't need the resistance. The MSD coil connects straight to the 6a ignition so the coil lead was just there not hooked to anything so I decided to use it for the MSD turn on. I may try to replace the underdash wire, but it looks like a job. It shoild be able to turn on the alt and the MSD as it is I would imagine though, but I want to do it right. Any suggestions on the best way to replace the resistor portion?