[Kitch428m21]

I would do this first before I did anything else. Put a digital volt meter at the solenoid wire and the other to ground when the no start occurs.
If you have 12.5v with key in crank position, then it's definitely starter issues.

["QUICK-SILVER"]

Originally Posted by MescaBug

The engine is a 74' 400, with auto trans. I notices yesterday that there was a sensor located on each heads. Driver side sensor is the 'cold feed switch'. And the passenger side is the 'hot coolant switch' or 'thermal override switch'. Correct me if I'm wrong, but that sensor is supposed to prevent the engine from starting if it's too hot, somewhere around 240F.

No such thing as a hot no start switch. The unused plug-ins on the engine are for smog components that your car didn't have. So nothing has to be plugged to them.

You don't need a service manual to check out the starter. The (S) terminal on the starter solenoid should have power to it, when you turn the ignition switch all the way over to crank. That's a small terminal that should have a purple wire on it. If it has power, in crank position, the starter solenoid is bad. If no power to it, in crank position, hook up a temporary push button to start it, untill you get the wiring straightened out.