6 volt positive ground charging question??

I have a bone stock 37 Dodge. I noticed the other day that my amp guage jumps around alot. At speed it will stay about halfway between 0 and +15 but then will drop back down to 0 for a bit, then jump back up agian. Sometimes it will even drop down to about -5 or so and then jump back up again. Not sure if this is normal or if I have a problem with the generator, voltage regulator, or just a frantic gauge. The battery seems to be staying charged, but I haven't driven it much lately. Any suggestions would be appreciated. Thanks

 

You have a cutout?

6 volt systems always act strange Pos or Neg! Like vacuum wipers

You can get a 6 volt pos ground alternator ....Ford A shops sell em.

 

If your wiring is good then it sounds like you may have a sticking voltage regulator, bad brushes in generator, or like you said, an old ammeter. Easiest way to find culprit is to substitute another ammeter and try again and see if it is any better. If not, then another approach is to take a voltmeter and put it across battery with engine running and see if it moves up and down like the ammeter except at around 6-8 volts. If it does then the charging system has issues.

Try and turn the headlights on while engine is running and see if the ammeter calms down. If it does then that points to the voltage regulator as the probable cause of the fluctuating ammeter.

If it still bounces then the generator may need to be rebuilt.