I can run my GT all day with no issue. When I turn the lights on it will shut down in about a half hour with the throttle up or 10 -15 minutes when at an idle. I have a 1979, 444, no alternator, just the box behind the plate under the steering wheel. Is this a grounding issue? I have tried to clean the terminal ends. Should I remove the regulator box from the plate and steel wool the surfaces to make a good ground? It will start right back up. I just run without lights straight to the barn. Guess it is telling me to call it a day.