Advice needed on how to identify/troubleshoot possible ignition issue?

[XH29N0G]

I am suspecting I have an intermittent ignition issue.  

I know I have a key switch issue, so I am concerned that I may have something else going on.  The car usually starts right up, but now will crank over and over.  The times it has started have often been after I have checked or reset connections, but while I don't think I can prove this is the case, it makes me wonder if something might be making the connections stick sometimes and not others.

I thought I would try check to see whether I am getting spark, and put an inductive timing light on the wire from the coil to the dizzy to see if it would light when I crank.  There is no light when I turn the car over, but I see light whenever the car actually starts.  Should this light flash when the car is turned over by the starter or is there just not enough juice until the engine is running?

My next step is to check the connections from the key to the ignition (through the bulkhead).  I have an MSD 6AL box and an MSD distributor.  I am looking for advice on what steps to take to check out whether I have an intermittent issue with the MSD box or the coil as opposed to the wiring to them.  Any help or thoughts will be greatly appreciated.  

I just did the check of the coil and ignition by putting a sparkplug into the lead from the coil and jumping the magnetic pick.  I see a spark jump.  I then tried to see if I could see a spark jump from the distributor leads and so far, I have not seen anything when cranking.  I am done for today and going to resume later. 
 

[XH29N0G]

A quick update.  I found a problem and will see if this fixes it for good.  

I hooked up a voltmeter (one side to ground and one side to the hot wire for the ignition from the key).  I see 12 volts when key switch is on and I see no volts when cranking.  It looks to me like the replacement key switch (or more likely - another connection) has a problem.


Update:  I pried open the pins on the dash harness to see if they were not making a connection to the harness for the key switch and the car started right up.  Looks like the problem is solved.

[b5blue]

 Ignition switch has 2 positions with 2 wires. Start and run, while cranking factory wiring is built to bypass resistor to supply full 12V to coil and in run position switches to fed through resistor. What I found and modified is the ignition switch connector, the long white one has a real crappy set of connectors. Thin tubes that slide into each other inside the plastic connectors. Look at the large red wire that feeds the switch, it looks like and should supply 30-40 amps to everything you feed while the car is running. (Think about it, that is a lot of stuff.) It all must pass through a crappy thin set of tubes that really don't even maintain a tight connection to each other. They heat up and act as a resistor before even reaching the switch.
You've added demand to the ignition load that was meant to only feed resistor/coil/points, a "dumb system" with no real electronics. I recently replaced my entire wire harness set with new and found (After getting pissed and cutting that entire new connector set out of the car.) that even new those tube connections are not tight. I could hold the wire on one side and spin it, the other end of the connector just sat there like there was a bearing between them.
So they are thin, unable to carry much load and contact between them is poor at best. This is true for the entire connector set both in and out volts/amps will suffer loss. If you have been around many 70 up Mopars you'll see many have browned connectors at that red wire from the extra heat, some even melted.     

[b5blue]

 Here is how I fixed the problem. I bought "Alumiconn" connectors and installed them to replace the crappy connections. They can handle the load demands and are a sealed simple solution. It's not going to "look" right but it works, I even used the 3 port to bind start and run into one feed as my Firecore RTR system uses a full 12V coil with no resistor needed. Next I tapped ALT. output (Black) to feed a 40amp control relay under the hood. The ignition switch now only turns on the relay and the relay feeds ignition through a very short run of (Fused) wire.
I've diverted about 15 amps load from inside the car, greatly enhanced the connections at the column and run a full 13.5 voltage to ignition, up from reading 8-9 volts prior. (I've fed the electric choke on my carb with it's own relay also so it works fine without drawing from the ignition feed.) I've also installed a 120AMP Denso ALT that can output 60AMP at idle and run a parallel 60AMP fused 8 gauge wire to the black wire side of my ALT gauge to split alt output load between the factory black alt output feed and the new 8ga. wire.
If you request samples you can get one 2 and one 3 port connector from AlumiConn free. Don't worry about the aluminum aspect of these connectors, they are rated and fine for both aluminum and copper solid and stranded wire by design. (Even wire nuts are a huge upgrade.)
http://www.kinginnovation.com/category-pages/products/alumiconn.php     

[John_Kunkel]

The MSD needs no ballast resistor, simply eliminate it and hook the wires on both sides of the ballast together....use this to power the small red wire on the MSD.

[XH29N0G]

Thank you both.  I am running without the ballast resistor and the issue with the crappy connector resurfaced.  After sending my 'solved' message, I drove with my kid (in his car - a 1981 528I that our neighbor gave to him after saying he would sell it for 1$) to a test.  When I got back, I decided to take the charger for a spin, and the problem resurfaced.  Since I have a multimeter, I can tell it is the connector.  So that is my next job.  I won't get to it until next weekend because I have some work stuff that is pressing, but I now I have a good idea of what to do.  Thanks for the information and for the point about the amps going through that part of the system.

[b5blue]

  For years I'd run a separate ignition circuit and toggle switch and had no ignition issues. (The car had been race only for years when bought.) The change in 70 to column mounted switch created this weak point and when I restored full factory operation to my old harness the crap started. Intermittent problems are the worst and this had me chasing my tail for a long time. Only during new harness install pre drive hot checks did I pickup an issue. The new Pioneer Super Tuner I installed at the same time as the new harness would cut out and go dead. Grabbing connections for a wiggle test I tracked to that connector and the rest I've explained.