I have been thinking about the alternator dark blue wire and I do not see where it ties into the ignition circuit. It appears to go from the alternator to the bulkhead. I don't see a schematic that shows the alternator wire connecting to the ignition wiring under the hood.
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The MSD RED wire calls for the "original coil "+" terminal" wires. This would be the twin brown wires according to this schematic. I tested the twin brown wires last night for both RUN and START voltages and that connection did show both voltages.

I have tried the following and still I got the ammeter and both voltage gauges bouncing:
- Blue RUN wire and Brown (single wire) START wire (idled and started fine but had the bouncing electrical gauges.
- Blue RUN wire and Brown (single wire) START wire connected to the twin brown wires (idled and started fine but had bouncing gauges.
- I have not tested just the two twin brown wires.


So I have tested the two wires together and then tested the four wires together and both combinations are giving me the ammeter bouncing around on the "+" side and the voltage guages bouncing around from 12-16 volts.

Any suggestions?
Please keep in mind that all three gauges were fine before I made the ignition box swap.
Thanks

If you check mymopar you can see the triple T in the '70 challenger "A" wiring diagram which is what I was going by. OK it starts/runs but the voltage is all over the place? I'm at a loss so far as to why the voltage is not reasonably steady but an intermittent connection is what is jumping out at me but I know I'm missing something EDIT I think I'd jump the MSD directly from the batt positive and negative posts to try & pin down if the prob is in the MSD box or in the wiring, we gotta get some progress going

Here is a wiring diagram for a hot rod set up using
a Mopar ignition

I am referencing that schematic too and it backs up my thinking of :

"" The MSD RED wire calls for the "original coil "+" terminal" wires. This would be the twin brown wires according to this schematic.""

It is the only combo that I have not tested yet. But this is the same thing as using the Blue RUN and the Brown START.

Thanks guys.

The brown and blue have to be tied together and all should be fine. The extra brown just jumps over to the coil for a full 12v on crank only, then the blue keeps it running.

I have the Blue RUN wire and the single Brown START wire connected together and it started and idled fine except for the ammeter/battery gauge/MSD 12v feed guages going berzerk.
Then I tested the twin brown wires and they both showed 12v START and 12 RUN also which I thought was weird.
Thanks MR. P. and 70
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""I think I'd jump the MSD directly from the batt positive and negative posts""

My first test was having the HEAVY RED wire from the MSD box going to my 40a fuse that comes off of my starter relay. The gauges showed bouncing. Then I tested it again with this same wire going to my positive battery post cable and the gauges showed the same thing.
I have the HEAVY BLACK wire going to my intake where I have three body grounds mounted together on a bolt. I will try to take this same wire to the negative battery cable to see if this makes a difference. Maybe my main ground going to the intake is the issue.

Thanks allot.

Its was wired right, just strange the amp gauge did that. Is the box grounded to the block good? I always have issues grounding them to the inner fender or something like that. Was it a new box?

The box is new and I used a voltmeter from the pos of the battery to each of the mounting bolts on the box and I got my 12v signal. So I am assuming that the box is grounded well. But I will move the HEAVY BLACK ground wire to the battery cable.

Thanks

After discussing this with an EE, I am now wondering if I am seeing electrical noise issues coming from the coil wires (435v). My coil wires and my volt gauge wire are running parallel left to right along the firewall. The volt gauge wire goes inside of the car, under the dash and is mounted next to the other volt gauge. These two volt gauge wires are wire tied together under the dash which might explain why both volt gauges are being affected. This could be the cause of a timing issue that I am having since installing this MSD unit too.

I am waiting on a response from MSD to see if this is a possibility or not. These are my questions to MSD:

* Since I have one of the volt gauges wired into the small red wire shown, could there be electrical noise from the MSD box that may be affecting this gauge?

* I have this volt gauge wire running from the passenger side to the drivers side along the fire wall and so are my two coil wires. Could the coil wires be leaking into this volt gauge wire?

* If this is electrical noise, could this be the culprit for my 30 degrees of extra timing that my two timing lights are seeing?

EDIT:
MSD says there should not be interference going into my volt gauge wiring. A bad ground might be the issue.

Your definitly gonna have to reset the timing after installing the msd.