Volts really high with acceleration.

Im having an issue with my volts going really high as I accelerate moderately on a 68 barracuda. the highest I have seen it go is 18V! When it is this hot i cant even touch the lights in the cab of the car because the bulbs are so hot. I went through 2 voltage regulators and had my alternator checked at autozone and they said that it is fine. it looks like the engine bay has been painted black before. Could this thin coat of paint on engine bay cause a grounding issue? Is this a situation where it simply has to be metal on metal? BTW I have a cheapy VR from autozone, it however is brand new.