KJK, sounds like Pontiac Jim helped you find that dieseling! dieseling is caused by two things.......
1) something glowing hot in the combustion chamber
2) too much fuel still entering the still hot chamber on shutdown
you have to find the cause of one or the other, in some rare cases you could have both. So maybe just maybe that short at the MSD box was glowing the plug hot, hot enough to fire off the residual mixture. You fix the short, you fix the problem.
conversley an overheating chamber, from say ...."Overheating", Ha!
or running too hot can cause the metal elements or crud to glow red hot in the chamber and fire the mixture, so it keeps dieseling.
when it runs out of fuel it will stop....or it runs out of heat source it will stop.
By shorting the choke on the MSD box you may have actually been the only guy in the known universe to be able to make both happen at once, the closed choke making the cylinder mix richer, the same short making the plug glow hotter!
At least that is my theory and I am sticking to it
who knows where the elecrical paths of that short went
PontiacJim is right about the heat crossover, I have done it both ways, racers may need it closed on the track, they may want a denser mixture. But with the heat crossover open your car will run 10 times better and smoother as it vaporizes the mixture easily and therefore is more efficient.
I have seen Geeteeohguy talk about that crossover as well and he is spot on.
Do you have a heat riser valve? It is in the passenger side exhaust manifold and works off a thermostat spring: cold it shuts and directs all of the heat back to one side of the exhaust......
through the crossover. If it sticks closed it can give you some problems, sticking open, not so much........... unless you live in Boston.
But then you have other things to worry about today..................., as you won't see the car until july!
If you do live in Boston (a great city!)..................
Nevertheless, I recommend just duct taping a snow shovel to the front of your vehicle, drive south until someone says, "Hey, What is that thing?'......Stop.....Buy a House!
and get warm
Then check the Heat Riser valve.