crank - no start

[euroZ06]

Hi all ,

So im dealing with something that should be simple, but I'm not exactly sure how to fix it. 68 Charger 383 with MSD ignition.

Long story: I was accepted to a fancy car show, and the day before, I went to wash the car and the car wouldn't start. I started checking everything, only to find I wasn't getting a spark. So I figured either my MSD ignition box was fried or MSD ignition coil. I went out and bought a new system, but same result. The new MSD box has an LED light that lights up when the ignition is on and should be flashing when cranking, and I noticed that the light goes out when cranking, which means it gets the power to turn on when ACC is on, but once I start cranking, the box is no longer powered. To get to the car show, I hotwired the box directly to the battery, and the car started and ran no problem. So upon returning home, I started checking, and this is what I have:

I have a new alternator with a built-in ballast, so the one on the firewall isn't used. The system was wired to receive the 12V ACC from the blue/white and brown wire that are connected together (my understanding its ignition wires that used to go to the ballast). That same wire where I used to get my 12v also runs to the alternator (also connected to the ignition wires). I checked my firewall connections (took out the connector, cleaned it up a bit, nothing jumps at me to be wrong/old). When I put ACC, I'm getting 12V at the blue/white wire and 0v at the brown wire. Once I start cranking, both blue/white and brown wire are only getting 4v (which isn't enough to power the ignition box). So the question is: where did I lose the voltage? Is it possible some ground wire is bad? where would ground wires be for this (ground at battery is ok, I can hotwire the ignition box to the battery and everything works just fine)?

One curve ball, but not sure if relevant. I recently put in a high amp alternator (direct replacement for my old alternator, but old alternator wasn't high amp). This alternator doesn't seem to work well (lights dim/fluctuate when at idile/low rpms). I already spoke to the manufacturer and sent them my old alternator to be upgraded to dual pulley. Since I have a wire from ignition wiring running to the alternator (same wire feeding the ignition box), could the alternator be doing some weird draw of power when I'm cranking? Should I somehow disconnect the wire running to the alternator to eliminate it as the cause? i don't want to burn anything up by disconnecting the wires lol.

I have some pictures of all this on https://www.forbbodiesonly.com/moparforum/threads/emergency-help-crank-no-start.260702/#post-912435029 (not sure if allowed to post)

[hudak69rt]

My doin the opposite after it being wired with msd. Found out it's blowing ignition fuse but not sure why however I did call msd and they said only use battery for power not alternator and any kind of resister will not give it a constant 12 volts my resto shop has given me a lot of headaches but best of luck!