6 volt regulators have different-resistance magnetic coils to operate the points, so they're not interchangeable. The resistors that do the field current control when the points open are also different. The mechanics of making the adjustments are pretty much identical, regardless of voltage.
The cutout relay is the only thing that prevents the battery from discharging through the generator armature when it's not producing voltage higher than the battery terminal voltage. There is no diode or other reverse current prevention built into the generator. It's a simple on/off switch that connects and disconnects the generator from the battery, but it's controlled by armature voltage, not a mechanical switch handle. Early Dodge cars and trucks used a chain-driven motor/generator system that turned with the crankshaft all the time, and provided starting and charging functions with the same unit. It functioned as a starter when battery voltage was higher, and reversed current to charge the battery when the armature voltage rose higher than the battery. The system had a BIG knife switch on the dash to connect/disconnect the circuit, along with the ignition system. The drawback was size and weight- - - -the motor/generator was almost as big as the engine.
There is a small winding on the cutout relay armature that's wound in the opposite direction than the "pull-in" winding that not only stops the magnetism during reverse current operation, but it actually creates an opposite-polarity electromagnet that pushes the points apart. That, along with the spring tension, is supposed to snap the points open quickly and avoid sticking. The air gap adjustment is vitally important to that system operating correctly.
The ammeter is essential for monitoring charging current while making the adjustments, including the current and voltage regulation, not just the cutout relay. People are so accustomed to solid state devices and computers doing all their thinking for them that a simple mechanical relay voltage and current control system becomes mind-boggling. Some people only know how to turn the thermostat on the wall to control the temperature in their homes- - - -they would freeze to death if they had to cut and split firewood and run a wood stove to keep warm! DC generator/regulator systems are like wood stoves- - - -they work, but you have to be smarter than a 3rd. grader to make them do their job!
Jerry
