Hi l have a 59 corvette with a stock generator that the Amp. needle is steady when idling and jumps half way to the plus side and back to center rapidly when I accelerate over one thousand RPMs and the tack jumps also. It also seams to have a miss like a momentary lack of elect. Could it be the regulator ?
Could be many things, have you done any testing? It would be nice to know what the voltage does when this happens. Is the tach electric or mechanical? Is the generator belt tight and in good shape?
Check the generator brushes. If they are warn short, they could float at high speed. Also lube the tach cable.
Worn or sticky brushes, out of round commutator, worn out rear bushing. Time for an overhaul. Be careful if you buy a new regulator. A lot of the "new" regulators are impoted junk and have problems right out of the box. So called "rebuilt" units can be even worse. Try to find genuine GM parts or Standard brand parts, made in the USA. I****ume you want to keep your car as original as possible but alternators are not a bad idea.
Had a similar issue on my '61 Corvette. Turned out to be a broken wire where they attach to the generator. You couldn't see it at first, and it would touch itself intermittently. Another common issue is the ground strap that is attached to the regulator case. It tends to loosen over time.
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