In Reply to: Charging system 51 8N 6V +Gnd posted by Clarke on January 12, 2020 at 12:48:59:
Ditto to what TOH said. Verify the wiring is all correct. Take your battery, generator, ammeter, switch, voltage regulator to a trusty, local shop -I'd use someone who knows old Fords - and he can test and/or rebuild if needed. Don't assume because you have a 6V battery it is wired correctly. Your '51 Generator should be the 3-Wire/2-Brush 20 AMP unit, B-Circuit design, with the angle (side) mount distributor, generator mounted on LH side, and NO Ballast Resistor. If you are burning up VR's, that is a big clue the wiring is all mucked up, not due to a bad VR.
FORD 8N TRACTOR WIRING DIAGRAMS:
FORD 8N TRACTOR GENERATOR - POLARIZING via THE VOLTAGE REGULATOR: