OK, I racked my brains over this tonight & I still can't figure it out. I have the MSD 6AL box with a billet MSD distributor on my '68 bird, 400. I believe everything is wired correctly. I don't have the tach adapter installed yet. Black ground to battery, thick red to battery, orange to + coil, black to - coil, and the small read to the pink/yellow wire that originally goes to the + coil side. I'll crank the engine, it fires, then when I let go of the key to shut the starter down, car immediately dies. It's getting fuel obviously, & it's getting spark when I'm cranking it to start it but it seems to lose spark as soon as I let the key go. Any ideas?? Should I re-route the small red wire or do something else? I haven't called or emailed MSD yet, I just was able to try & fire the car up for the first time late this evening. Also, the wiring harness is a brand new reproduction harness from NPD. Thanks guys.

Was this motor firing before the MSD ? I mean with that harness ? From the factory, when you have point ignition, there is a yellow wire coming from the starter and going to the coil + along with the ignition + from the ignition switch. This was to give full 12v while cranking, then once started, the motor ran with the 9v from the resistor wire (ignition from the switch, cloth type wire). When you put the key on (not starting), do you have voltage at that cloth wire ? If there is no voltage there, the trouble is either the ignition switch and/or harness between switch and that wire. It's definitely not your MSD since it obviously works. I'm pretty sure that pink/yellow (cloth) wire of yours only has voltage "while cranking" and no more at "ON" position, thus engine only running with key at "cranking" position. To get proof, run a jumper from the positive battery post to that pink/yellow and crank it. If it stays running, you know that is your problem. Let us know the outcome. Frank.

Sounds like the ignition switch to me. Start the car, but don't let go of the key once it starts. Turn it back slowly until the starter disengages. If the car runs, the switch is bad.

The car started without problems when I first purchased it, it had a HEI distributor. The original wiring harness was hacked up pretty bad so I replaced it with a reproduction harness from NPD along with putting the MSD system in (6AL box, billet distributor, & MSD coil). I ran the testing procedure from the MSD website showing to short the violet/green wires & watch for a spark from the coil wire...there was spark so the 6AL box is working. I called MSD this evening & the tech guy thinks its the magnetic pickup inside the distributor so their sending a replacement out. Hopefully this does the trick, I'll keep you guys posted.

I had the exact opposite problem with my MSD box I ran years ago. It would not spark while cranking, however, as soon as I would let go of the key, it would fire as long as the engine was cranking at a good pace. I also found that the original resistor wire, since the first gens did not use a ballast resistor, was starting to melt with the use of the box. I took the box off, and everything fired right up as usual. I believe your issue is a wiring one, but if MSD thinks its the pickup then try that first. I too wired my box exactly as MSD had on the diagram.

The more I think about this, the more it sounds like the box is wired for power only when cranking? If that makes any sense?

Yeah, that makes sense. Thats what I thought at first too, actually had myself convinced of it. After I shorted the box & got spark with the key "on" I just stood at looked at everything for about 20 minutes & never touched a thing b/c I was out of ideas. I put the new magnetic pickup in tonight but they call for some silicone to be used so I'm letting it dry overnight before I try & start it. Fun times....ugh.

Could it be a coil problem? Maybe the hot to the coil being wired to only be hot when cranking, just like the starter hot wire, which is killed in the "on" position, but hot on the crank position. man that does suck!!! Sorry to hear your frustrations.

Finally got it started. I don't think it was what the MSD tech said it was though. I noticed that the yellow/pink wire was hot to the touch as soon as I turned the key on, so I knew there's a problem somewhere. I had installed a new Summit mini-starter & it only had 2 posts as opposed to 3 posts like the original. I asked the Summit tech guy when I purchased it & his exact words were: "just put the two wires on the one post & the battery wire on the other". I re-asked 3 times while I was there but him & another tech said that's the right way. Welllll, no it's not. After knowing the pink/yellow wires are hot to the touch, I googled a few different things & found a note on a forum that explains the yellow wire does not get connected to the 2 post Summit starter. So thank you Summit tech department for days of headache's & almost burning my car up.

So after correcting this, the car fired right up! Sweet. Then I went to shut it off & it wouldn't turn off. Great. I searched the MSD website & it said to put a 1A 100V diode on the #4 wire going to the voltage regulator. I'll try this as soon as I find a diode, Radio Shack doesn't carry this type. Ugh....

Lol...mine did the same thing, wouldn't shut off. When I put the MSD in many years ago(6A), it actually came with the diode. Guess they aren't doing that anymore. Glad you got things sorted out...and lesson learned, always double check the info you get from summit guys

Boomstick, I also had the same problem,I even ordered a new ignition switch, still had the same problem, I have the small diode but didn't want to cut up the orginial wiring, so I pulled the Gen light out from under the dash and now it works.
I have gauges so I know the charging system is working. It's a tem fix,still scratching my head on what to do next, if I find a fix I'll let you know.
Good Luck.