In Reply to: ammeter / light posted by Peter Nelson on October 23, 2018 at 08:11:18:
Assuming the needle only goes a needle width or less and doesn't peg hard to the discharge side, and the lights are working you have the lights wired correctly.
If the charging system is keeping the battery charged it's probably functioning as it should. You can use a known to be good accurate ammeter in line between the regulator and battery to check output. You can also use a volt meter or meter that reads bleed voltage off the hot battery cable. The latter two methods only read voltage, not amps however. Or you can run it with the lights on doing chores as you do normally. If the battery stays charged you have your answer.
Remember this. A Ford in good tune (or any other tractor of the age) starts easily especially in moderate weather with minimal strain on the battery. Additionally there is little battery draw through the primary system to keep it running.
Fuel and ignition off, lights on if not wired through the ignition. Wing it over for a good bit. Don't worry about overheating the starter, but don't go nuts.. Those starters are tough and built to take it. THen start it and see if your meter moves.
Discharge at idle is normal. Sometimes it will take half throttle to get the gauge to show any charge. And yes.... I know it's not a 12v system with an alternator. It still takes speed off idle for a positive charge to be indicated on the amp meter.
The ammeters in those tractors have wide needles, wide marks and relatively low output charging systems. Even at full charge you may not get more than a full needle width movement in the positive direction when charging a low battery.
True test will come this winter. Lights, radio, heater fans,(on high blow),butt warmer, steering wheel and cup holder heaters on high as you break trail from the house to the county road. Stay warm.