Small Red

This wire is responsible for turning the MSD On and Off. Connects to a switched 12 volt source such as the ignition key or switch

Yes here is exactly how it's wired in the attachment straight out of the MSD instructions except I am using the starter sol. stud for large RED and engine/firewall for large BLACK.
Ron

I know where your going now per instructions



Small Red says - From positive side of coil / From original + side coil terminal

In a Factory Mopar world , that might bee only 7- 9 volts positive side of coil , because of the Ballast Resistor resistance

However if you took it off the feed side , or ignition switch side of the Ballast Resistor , you would have the full 12 - 14.5 Volts going to the small red


So with that said , Take your volt meter , and supply that small red off the feed side/ignition switch side of the ballast resistor (Full 12 - 14.5 Volts engine running)
NOT the resistance side of the ballast resistor going to coil


And honestly

If you have any issues down the road , the LARGE Red and Black wires should bee directly fed off the battery terminals

Peace

OK makes perfect sense, tomorrow I'll see what the Fluke Meter says. Since it's the factory wire that used to go to + of factory coil it may be regulated by the ballast.
Thanks
Ron Sannino

You got it

No work on Labor Day

LOL

Peace

You would think 12v is 12v but I've seen it first hand on a hydraulic power pack unit that used a 2300 Ford, basically a Pinto motor for power. It had Duraspark ignition and they got tired of them failing so the owner had a CASCAR race team and lots of 6AL boxes in stock so he told the shop to swap it over. The tech wired it exactly like yours and it never offered to run. I told him it had to be wired directly but he was having none of it and sent out for another new 6AL which also refused to fire. Hooked it direct to the battery and vroom.

I have no idea why it matters but it does.

If you are using the blue wire for your switched 12v source to turn the box on and off, you need to bypass the ballast resister so the blue wire supplies constant 12v when switched on.

Kevin

Like Kevin said

If you want to keep the ballast resistor in place for that factory appearance and use that same blue coil wire
Or just wire it off the ignition switch feed side like I mentioned

Anyways , something like this first picture

Or

I removed the resistor element on the backside , and soldered in a heavier gauge wire from terminal to terminal
Then fill with two part epoxy

Looks factory and no one knows
Stole picture from internet , second picture

very easy to test voltage at the battery, coil, or resister with a multimeter.

Yes I've made ballasts before for a few FBO systems.

other then the trigger wire i usually think its best to not tie into ANY of the old wiring. Use new wires and wire the MSD completely independently directly to distributer, battery, coil. You can then wrap it and hide with factory harness, but keep the wiring independent.

I'm dealing with the ballast on my car too.I undrestand that the red trigger wire should have constant battery voltage on it ( mine is between 13.5 and 14 volts while running),what should I be getting on the orange wire at the positive side of the coil?

check voltage at the battery with engine running and it should be the same at the positive side of the coil if the ballast is bypassed.

MSD Tech



Next, lets review the coil wiring. The ONLY two wires that should be connected to the coil are from the MSD. The orange wire connects to coil positive while the black wire connects to the negative terminal. No other wires should be connected to the coil terminals! Also, do not touch or connect any tools to the coil. With the MSD connected there will NOT be voltage on the coil terminals unless the engine is running – and in that case there will be over 450 volts due to the CD technology of the ignition. Again, the only two wires connected to the coil are the MSD Orange, positive, and the MSD Black, negative.

MSD Tech

"One common question in regards to MSD Ignition controls is “Why isn’t 12V power on the orange (COIL +) wire?”
The main reason 12V won’t be present at coil + is because your MSD ignition is a Capacitive Discharge Ignition. Like all CD ignitions they use a large capacitor to discharge 420-480 Volts to coil + and coil – will normally be connected to ground. (That’s why you wont see +12V on coil +) "

Got it. Thanks for the reply.

You need to research what you are running, This is direct from MSD.

Have a look...
https://documents.holley.com/techlibrary_coil_compability.pdf