MSD Distributor with a Stock Motorcraft Box?

[Fast79Chief]

Hey y'all, yesterday I installed an MSD 8519 Pro Billet distributor in my 79 360 Cherokee. I left the stock ignition box in place for now. Had to add one ground wire to the MSD dist. housing to make it a 'plug and play' installation with the stock wiring coming from the stock box. Added a set of HEI type wires and the old girl is running very good.
Does anybody see a problem with leaving this setup long term? Of course MSD wants everybody to buy their $300.00 boxes for their distributor ... but apparently it will work with the factory box.

Appreciate any input from experienced wrenchers. Thanks.

[REDONE]

I don't see any issue with that at all. The stock motorcraft boxes where pretty decent units, with good curves and supposedly a built in retard-during-start.

The issue with the stock boxes isn't in their performance, just that they're all old by now (and corrosion has run its course), and the replacement boxes (Chinese) had a high rate of bad-out-of-the-box/immediate failure.

I suspect that the new replacement boxes (last one I bought was Korean) are really just stealth HEI, which is good, but not really the same as the original Motorola motorcraft boxes. I think you should run the stock box as long as it runs like you want it.

[tgreese]

The only issue I can think of would be polarity. You can read about the polarity of a VR signal here - http://www.megamanual.com/ms2/pickups.htm

There are only two ways to connect the trigger to the module. If you had an oscilloscope and a working Motorcraft distributor, you could measure the signal it makes and determine the proper connection. However, lacking that, you should be able to deduce from the wiring instructions what the polarity should be. The instructions tell you how to connect a Motorcraft distributor to the MSD module, and how to connect the MSD distributor to their module. From that you can determine the proper connection of the MSD distributor to the Motorcraft module.

The module can only sink a certain amount of current without melting. But that's not under the control of the distributor, but instead determined by the coil and any ballast resistor present.

[Fast79Chief]

Thanks you guys ... this is good stuff for all of us. Today, a wet, rain soaked day, was the first time since I bought this Jeep that I turned the key and it fired right up! Yesterday I saw that my stock Motorcraft distributor had 3 wires coming out of it, and noticed that two of them were the same color as the MSD 8519 distributor wires, and another black ground wire. So the MSD only had the 2 colored wires coming from it so I added a black ground wire to the housing. Put female spade terminals on all the MSD wires and plugged in the factory harness lead, matching colors. I am running the factory coil right now. I'm sure it's at least 25 years old or older so I'm looking to replace it too.
You guys seems to know your way around these 360 motors ... how much coil voltage can the Motorcraft ignition box handle? Have you heard of anybody (or did you do it) replacing the factory coil with a higher output coil and KEEPING the factory ignition box? Cause that's what I want to do.

LEt me know your thought on this please. I'm going to see just how much better I can get the old girl to run with simple needed changes.

Thanks!