Here is the basic story. 67 289 V8 with pertronix ignition. When I check the (stock) alternator guage, I notice that it kind of oscillates back and forth rythmically. It doesn't move back and forth very far just a few degrees. I moves from right around the midline position toward the C side, back and forth at a cycle of about once per second or maybe a little faster.

Now that I think of it I don't remeber trying to check it while I'm moving just when idling at a red light for example. Next time I drive it I'll try and check it while I'm in motion.

I don't know if this is normal or if it means anything. I'm just curious.

BTW the battery is about 2 months old and the alternator seems to work fine, the battery stays charged. But I have not actually tested it with a meter.

Any ideas or comments would be appreciated.

 

Just to make sure I am explaining it correctly. THe actual needle in the guage moves back and forth slightly from near the center position to slightly into the C side or right side.

 

That's normal. "If it ain't broke, don't fix it."

 

Count yourself lucky that you have one that moves at all. Most of them just sit there and so nothing.

 

Very frequently the coil inside of the guage will burn out. These can be replaced but it is a pain as you need to remove the guages. I agree with Soaring...just live with it, not that critical