Originally posted by tucker:
It sounds like the brushes in the regulator are bouncing
at high engine rpm... it could be weak brush springs or a rough slip ring surface.





Or a loose connection to one or more of the diodes in the rectifier.

Or an out of contour brush due to brush chattering, this casues arcing which ultimately reduces power transfer to the slip ring which causes reduced rotor field strength which casues lower induction within the stator which equates to reduced output.

A loose connection in the stator, or a wire in the stator has had its epoxy insulation chafed through by vibration and is intermittently shorting out one winding in the stator.

or even simpler, the belt is slipping over the altenator pulley.

I feel sorry for the people who don't drink. When they wake up in the morning, thats the best they're going to feel all day - former President Lyndon B. Johnson