problems after digital 6AL install

[74 340 4speed]

I recently put a digital 6AL on my 74 'Cuda and I immediately noticed a difference in idle quality and throttle response.  However, 2 weeks ago, I was driving the car and it just quit on me, right in the middle of town.   The only way the car will stay running now is if I hold the key in the crank position.  As soon as it goes to the run position, it dies.  I have checked and redone the connection of the small red wire from the MSD box to the brown wire and blue in the factory harness.  I checked them the last time I redone the wiring and I had power when the key was in the run position with one wire and power to the other when the key was in the crank position.  This is getting really frustrating.  I am thinking about putting a toggle switch on the car and run another wire directly to the battery and use it to control power to the box when the key is in the run position.  Any ideas?

[MEK-Dangerfield]

Just to be sure, did you eliminate the ballast resistor when you installed your MSD system?

[Chryco Psycho]

so you have confirmed that you have 12v at the small red trigger wire with the key in run position

[dodj]

It is connections or the ignition switch. Bulkhead connector column connector or the connection you made. Use a meter and determine where the 12 volts goes missing.

[Tonker1]

'74 340 4speed', did you ever resolve the run start ignition issue?
I've just installed a new complete wiring harness from painless performance MSD distributor, MSD 6AL ignition control unit and I'm having the exact problem you are. Since this is my first wiring harness, I assumed I made a wrong connection or an earth that bypassed the starter when the key was in the run position. I'll be extremely interested to here if a solution eventuated from your situation. If not its going to be seats out, upside down time again under the dash!

[fantum]

I had a similar problem several years ago with my '87 van (318).  It turned out that there was an electronic unit of some kind in the distributor that had a "start" side and a "run" side.  The "run" side burned out and I had the exact same problem you are reporting here.  Is there some chance that you may be experiencing the same problem?  Maybe there's a problem with the MSD box.  I really hate electrical gremlins!

[Tonker1]

Everybody hates electrical gremlins! Although they are extremely satisfying when resolved. Working out electrical issue is like scrounging around in the dark, because you can't actually see what's wrong. I like rusted metal, because when I see it, I can treat, cut, replace, weld, paint and be happy!

The MSD distributor and 6AL were fresh out of the box last month. The engine did run back in January, but it was sporadic due to electrical malfunction. It was definitely an electrical issue, to explain the quality of the wiring when the car arrived, most of the connections were done by twisting the wires together than covering in electrical tape. Hence the full system replacement.

I doubt the MSD 8534 distributor has been wired incorrectly because the terminal is directional and the 6AL has a reverse flow management system preventing electrical damage due to incorrect wiring. I'm thinking I've wired the ignition wrong. Although I will look into your suggestion.

Any additional ideas would be much appreciated.