My '77 seems to be having a overcharging problem. My ALT gauge was acting up, hooked my volt meter to the battery while the truck was running and I get spikes of 17 volts, but usually stays at 16. Threw a voltage regulator on it, cleaned the base where it's mounted....no change. While idling, the gauge is fully pegged to the "c" side, but when I rev it up the gauge drops and fluctuates between the center and "c", then I drop it back down to idle and the gauge pegs again.


whats the deal?

 

One of the nasty side effects of poor grounding with the block and to the alternator is some highly weird charging problems. Friend of mine has a '72 Stang and he had nothing but problems with his charging system. Turns out after replacing the regulator and the alternator? Problem was a very screwed up crimp connection at one of the main grounds.

Just food for thought--It could be the alternator as well....but always check the basics.

S-

 

Tap the VR case with the handle of a screwdriver and check it again

 

unplug the regulator and see what it does