Voltage fluctuates when idling

[cuda2002]

Ok,

I installed a new engine compartment wiring harness and bypassed the ammeter last year, everything seemed to go smoothly. This summer, After tuning my 'Cuda , (383, XE268H cam, Holley single plane manifold, Hedman headers and MSD distributor, MSD box, new MSD wires and new spark plugs) I am noticing that at idle there is a 1.2 - 1.4 V fluctuation ( between about 14.4 and 15.8 V).  When I'm driving seems to be steady at 14.8V. The car seems to run fine.  Anyone have a thought on why the voltage is bouncing around at idle?

Thanks

[Chryco Psycho]

typically the voltage will be low at idle as the alt is not turning fast enough to produce 13.8V
 but if yours is going higher it is most likely a reg problem

[cuda2002]

Thanks, I understand the voltage will be lower at idle.  I wasn't clear in my question. The voltage  fluctuates between 14.4-15.8 V about every second at idle.  When driving it is steady on 14.8V.

[Chryco Psycho]

I understood exactly what you meant , , it still sounds like the reg is not working properly allowing the voltage to spike at idle

[MEK-Dangerfield]

Some people have trouble with the voltage dropping at idle, but your's wants to go to max. That's just crazy.   

It seems your alternator is working fine, so I agree with Chryco that something is up with your regulator. Make sure it has a good clean connection to the body, as that is it's ground connection. Maybe the new paint is hindering it there? If it has a good clean connection to ground and still acts this way, I'd say try another regulator. They aren't that expensive anyway.

[cuda2002]

Thanks very much. I appreciate the advice.