Finally got converted to 12 volts with SI10 alternator and installed a pertronics 11 with their coil in my 1950 GMC 450 firetruck. Starts right up, even after sitting couple days. Engine pulls a lot better. It gained about 4-5 mph top end too. It will maintain 49-50 on a flat both directions now. I'm happy with it. Went to the Mt. Nebo Chicken fry with it, small car show.