I've got an HEI with an external Blaster 2 coil for the wagon. With this coil setup you just plug the tach into the negative terminal on the coil. The problem is that my tach (and speedo) are jumping around all over the place due to the signal noise, but when I disconnect the tach wire the speedo works fine. I've already ruled out a short, is there a noise reducer or a capacitor setup that can solve this?
Found it! Called the MSD help line. For anyone else with this problem, the answer is a 10k ohm, 1.2 watt, carbon comosite resistor in-line.
