>>>> Is it normal for BOTH field wires to show 14+ volts or would one field wire show it and the other would not?

Well it seems I missed this point earlier. That does indeed seem odd. I wish I could try on my car, but the motor is apart and the battery out. I also realize that I have replaced my under hood harness some years ago so it may not be fair to make apple-to-apples comparisons with.

It is very interesting that your diode experiment changed the results, and perhaps you are on to something. In thinking about it more and looking at the wiring diagram, it seems clear my previous response is wrong. I'm not certain but I suspect what happens with the dual field alternator is that system (battery) voltage is on one field wire (blue) and the VR alters the voltage on the second field wire (green). It may be the difference between these two voltages which controls the output of the alternator. In a single field, the VR alters the voltage on the one field wire and it is the difference between that and ground which controls the output.

If the above is correct, then you latest measurements on the fields make sense. However, this does not explain why earlier you had high voltage on both fields. The voltage on the green wire should be controlled from the VR; if the VR made that voltage match the blue wire (btw, on my car it is solid dark blue and solid dark green that go to the alternator field), then there would be 0V difference, which I think means the alternator would have no output which does not make sense. Even if the MSD is somehow raising the voltage on the blue wire, I don't understand why the green would also go up. Please don't take any of this as gospel because I am not completely certain.

Is your car a 70? Do you have a 2 or 4 prong ballast? Do you have a dark blue instead/in addition to a blue with white tracer?

Dave,
My car has a Blue/White tracer wire from one of the field wires all the way back thru the bulkhead and up the steering column then it disappears going to the key switch. This is a 70 car with an 8 year old YO wiring harness and the ballast is removed with the MSD swap.

This is interesting, In the MSD kit, they provide a 100v/1a diode in the case of RUN-ON. MSD told me that I do not have run on so this is not my problem. But, if MSD provides a diode for RUN-ON and a diode keeps voltage from going backward thru a circuit, then the main cause of the RUN-ON is due to the box leaking back into the run circuit which is what I believe that I am experiencing.

The only guess that I can come up with on the 14+v on both field wires is the system appears to be "holding" a charge for some reason. The only theory that I have is that the box is leaking back thru the RUN circuit and it stays charged in the system. Once I completely disconnect the battery, then I can put a test light in-between the battery cables and the battery and my test light will light for a second and then slowly die out. Then I can put the battery cables onto the battery without a major spark. If I do not do this with the battery, then when I put the battery cables onto the battery I get a pretty good spark. I started a thread a few weeks ago about the spark at the battery and at that time, the MSD was not a suspect.
If the diode is the fix, this is not a major deal since a proper sized diode comes with the kit. This may not even affect those who run with a newer ammeter and newer digital guages.

Thank you again for your response. I won't know for sure if the diode helps my ammeter/analog voltage gauges until the weather warms up enough to start the car.

any updates?

Danny,
Thanks for asking and yes, I just got in from the garage.
After adding the diode on the MSD small red wire (where the CRANK/RUN/#2 inside voltage gauge are all connected) I now have NO MORE FLUCTUATING AMMETER AND BATTERY VOLTAGE AT IDLE!!!!!!!!!

This has been a long and drawn out issue but it came down to a $1 diode that is now keeping the voltage from the MSD unit from affecting the RUN circuit. At my idle rpms, my MSD CRANK/RUN voltage is steady and my battery feed is now steady and my ammeter is now steady AGAIN!!!!!!!!!! My battery is now showing 14.8v instead of 15.2 during high idle. So apparently my first and second voltage regulator are good too.

I will update my MSD5 Street Fire thread once I get the schematic updated.
I need to point out that the Street Fire box never missed a lick during this issue. It was all in the way that the two inside voltage gauges and the ammeter were fluctuating after the install. The only two things that I did different from the MSD wiring schematic, were adding a voltage gauge at the MSD SMALL RED WIRE/RUN/CRANK connection so that I can watch the ignition feed voltage from inside of the car, and I added the diode at the end of the MSD SMALL RED WIRE before it connected into the supply voltage/voltage gauge.
I mapped out the RUN/CRANK circuits along with the parallel ammeter wire upgrade and I was surprised how much of the circuits were affected by this feedback issue. I will post that schematic on Monday when I have it in front of me. After all of this, it appears that the ammeter and my cheap mechanical voltage guages mixed in with an external alternator voltage regulator are all to blame. I have read where alternators with built in regulators help absorb this feedback and also newer digital ammeter/voltage guages also help absorb this type of feedback.
I am a little disappointed with the MSD tech websight. After explaining all of what I have done on this thread, before I sent in my Powermaster alternator for the test, they told me that the small red wire would not cause my ammeter or voltage gauge issues. This is the main reason why I sent in my alternator to Powermaster. I asked MSD if the diode in the kit might help this and they said no since I was not having any RUN-ON issues. Since it is Winter and I have not driven the car since the install, my guess is that I would have had RUN-ON issues once the motor was up to driving temp.

Now I can install my new vacuum advance distributor!!!!!

Thanks again to everyone that kept with me on this issue. Now I need to write an apology to Powermaster letting them know that the problem was never the alternator that they replaced for free six months out of warranty.

Thanks again

That's great news that the problem is solved!

I wish I understood better exactly what was going on though. It seems the Streetfire unit was back powering the run circuit with a stepped up voltage for some reason.

Dave

I attached a sketch that I made showing "some" of the circuits that I think were affected by the feedback.
During the RUN mode, the ignition switch feeds 12v to most, if not, all of the car circuits. This sketch shows how the RUN circuit is connected to my ammeter, the MSD ignition feed voltage gauge, and the battery voltage gauge which were all being affected.
Once I drew it up, I could see how each one was being affected and the sketch just kept getting bigger, so I stopped. My dash lights were also fluctuating but I started to run out of paper so I stopped mapping it out.
But once again, the $1 diode which comes in the kit seems to have fixed the feedback issue.

I can't read everything on the wiring diagram you made, but notice that there appears to be other modifications around the ammeter. Not that it matters now, but I am curious if you ever tried the system without this modification in place? What is the intention of those changes?

The sketch was only made for my notes at the time, so that is why it is so messy.
I did the ammeter parallel wire bypass upgrade to relieve some of the amperge thru the bulkhead connector. I feel safer with this wiring change with the higher amp alternator. This change was done before this issue came up.

Thanks dave.

Robert,
This one kicked my butt!!

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EDIT:
Since I have posted this response, I have started up the car several times and the ammeter and both voltage guages are rock-solid at idle. The diode on the small red wire worked great.
Note: If you experience engine run-on or any voltage fluctuations with the MSD box, please consider using the diode that comes in the kit on the small red wire.