roasting coil wire

On MSD ignitions, the primary coil voltage is very high and is not compatible with most tachometers. The tach should be connected to a tach output wire, not the primary coil wire, and if it's not, it might be the cause of your issues.



http://www.msdignition.com/Products/Ignitions/Daily_Driver/6201_-_Digital_6A_Ignition_Control.aspx