I've troubleshot the '73 with the starting trouble, and all the connections and electrical flows seem to be fine. I installed a new solenoid, but this didn't do the trick. Would the voltage regualtor and/or starter be suspect? Smoke issued from the area near the positive battery post when I tried to start the car with the new soleniod installed. The starter has caused trouble numerous times in the past.
Is the battery cable corroded under the insulation at the terminal? All connections must be clean and tight at the battery, starter relay, starter, and block ground connection. If the battery is not being charged by the charging system then there will shortly come a time when the battery runs down and no start, on a secondary basis.
Any smoke means you're getting a high current draw. That means that solenoid is engaging the starter motor, but the motor has shorted out. You need a new starter.
These guys are on the right track. Make sure that all your starter wiring is good and the connections are clean. I'd have to agree that it sounds like the starter itself has gone bad.
