I've been using a Ron Francis kit and Classic Instruments guages on my 1929 Ford Hiboy roadster since the early 90s and have been reasonably happy with them. Two years ago, I began to have voltage problems that required two solutions: replacing all battery cables to fix a serious voltage drop, and laboriously cleaning and polishing every terminal. Life was good again.

Two years later, I've observed that the voltage at the ignition switch is 13.4, but the voltmeter reads 12-12.1v. I suspect a grounding problem, but due to the inaccessiblity of the ground connections and my age, I'd like to hear opinions before I do that.

Also, when I turn on the headlights at idle, the voltage drops to just below 12. When I blip the throttle, voltage rises to 12.5 and stays there. In the 30+ years I've had the car, I simply don't recall ever seeing 13v+ on the voltmeter.