I just ditched my old mopar ignition and installed a Summit cdi box (msd 6a copy ) and msd dist. Tach is a Autometer 5" .

Car runs nice but now my tach reads around 600 rpm too low . Tach is wired correctly to the gray tach wire from the box. Summit box is set to 8 cylinder

Someone mentioned I need a MSD tach adapter.................so is every car equipped with a MSD 6a and a Autometer tach running an adapter ??? Doesnt sound right....




https://www.summitracing.com/parts/sum-850620