msd 6a

[maxamus]

need help diagnoising msd box with GM HEI distribotor and coil. All connections are good and connected properly. No spark.

[Sparky]

There are a couple of different configurations for an HEI, it depends if you have a 4 Pin Module vs. a 5 or 7 Pin Module.
In any event, if you disconnect the points wire and/or the Magnetic Pickup connector, you can test for Spark two different ways.
1.) If you short the Magnetic Pickup wires together and then separate them rapidly the coil should throw Spark.
2.) You can also strike the White Wire to ground numerous times and again the coil should throw Spark.
This is done with Ignition Power turned on and Battery Power and Ground at the large Red and Black wires.

If you can provide mw with which module you have, I can provide you with the proper way to hook the 6A to the HEI.

Sparky