My volt gauge shakes up and down as the car is running. Seems that it is in time with the rpms of the engine. At times it moves up and down w/ a surge from the engine. I had compression checked and all is good. Did new injectors, MAF, o2 sensor, plugs dist cap an rotor wires and every thing emission related. Shop thinks its a high performance cam that is causing the rough idle. Could it be the alternator? This is a crate engine and every thing else checks out. Runs great except for the occassional surge.

 

Verify the dash gauge with a separate voltmeter. An analog meter might be best for that purpose, since a digital might not display the variations you are describing.

Get back with results.

 

Thanks for your reply. Where do I hook up the anolog volt meter and what do I look for.

 

Connect your voltmeter directly to the battery. Alternator variations should be detectable there. To test for the presence of any AC voltage. connect the positive meter probe directly to the alternator output stud, negative to battery negative or ground.

 

Thanks Vader. Will check it out when the car comes back from the painter.