Well I am just an industrial motor control electrician so what do I know?
Dan, you're obviously not particularly familiar with the construction and maintenance of an automotive starter. There are at least three methods of winding a starter, and the General Motors 6-volt starters are usually wound with three field coils in series, and one shunt coil to control the speed at a reasonable level. "High-Torque" 12 volt starters actually use a 6 volt armature, so there's a lot of interchangeability between systems. "Super-Torque" 12 volt starters that we used to install on the race cars are actually built with all 6 volt parts, armature and field coils. A starter is designed to run at a massive overload for a few seconds, then have a long cool-down period. The GM factory standard operating conditions call for a maximum cranking time of 30 seconds, followed by a 20-minute cool down. Try disabling an ignition system and actually running a starter for 30 seconds. It feels like forever. If an engine doesn't start in the first 5 to 10 seconds of cranking, something is drastically wrong.
6 volt starters will last for many years on 12 volts, as long as the engine is kept in a reasonably good state of tune. The "stomp start" stovebolt engine starters with the manual engagement of the pinion gear and a simple mechanical on/off switch will outlast a solenoid-engaged starter by a factor of 3 or 4 to 1.
Jerry
