I am getting some strange amp gauge readings in my '28 standard.
Here is what happens:
Start the engine and get a slight neg reading maybe 1 amp, as revs increase, output goes up to 18-20 amps. All is good so far. Now with the lights on at idle neg 8-10, ok, increase rpm and it goes to 0-1 up then to about 8 amps+. Add more rpm say 1400 and the amp gauge jumps over to 10 amps discharge. As rpm increases discharge increases, drop the rpm and it jumps back to the plus side 8-10 amps. I checked the current limit relay and the pionts are opening at 1400 and stay open untill the engine rpm drops back down. I swapped out the current limit relay with a spare and no change. I don't see anything in the shop manual under current limit relay or eleswhere that relates to this condition.
Is this normal?
Any ideas?

Hi,
Its sounds normal up until the sudden discharge bit, I do remember the gauges as being a bit "nervous" in operation though. Perhaps try a modern gauge before you go further? with the lights on do they dim at the same time? (youll only notice this in the dark)
Roger

I would believe your ammeter. Rather than concentrating on the regulator, I would look towards the generator (and the battery). Carefully inspect your brushes for wear and good, tight, wire connections (especially FIELD connections).

This may sound too easy, but make sure your (field) wires aren't flexing in one area (like at a kink), causing a make-break condition inside the wire insulation. I usually pull real hard on my wires, individually. If one 'stretches' I know the copper is broken inside.

It might just be, that your generator field is re-flashing itself, causing the temporary drain. As far as RPM, that might be flexing the wires back and forth, into and out of this condition.

I'm not saying anything you don't already know, but this is very abnormal, and it shouldn't work this way. It could also be, when you rev, a wire is rubbing on metal, and when you idle, it quits rubbing. More often than not, these kinds of problems are more mechanical than electrical.

Hope this helps. - Dave

Thanks for the ideas. I will let you know what I find out.
Dave

I never had a 28 before so I'm just wondering out loud here...is this the starter generator combination unit, or two separate units? If combined I thought maybe somehow your starter was becoming engaged at the increase in RPM?

JD, By 1928 these were separate units. Dave!

Ok, so now the resistance wire on the built-in generator thermostat assembly has melted and there is no out-put at all. How can I repair the the resistance wire? I will tear down the generator later in the month but I still have a local GM 100 year b'day party to attend and I would like to get there and back under my own power. Any ideas? Could it be the halogen head light bulbs drawing too much juice?
Thanks,
Dave