Trying to get an accurate reading on idle speed rpm for my 53 Manhattan. I just picked up this vintage analyzer. It runs off of 3 C batteries so no issues hooking it up to 6 volt positive ground. BUT, how should I hook it up to the car? Manual diagram seems to be screwed up seeing as the red lead is going nowhere (see pic below). Also, should the red lead go to ground and the black lead somewhere on the coil?
