Hi, I just joined or I would have been able to help you out on the tachometer question when you originally posted. I had the same problem when I replaced my dual points with the Crane electronic ignition XR3000 and used the Crane PS60 coil. The XR3000 comes with a resistor as part of the system and the coil doesn't come with one (the PS60 is rated for RPMs higher than the PS20 and PS40 which both spec a 6500 max.) It ran well with both the original resistor (somewhere in the wiring harness - I could never find it) and the reistor in the electronic ignition. However my tach stopped working - could only handle the one resistor. After looking closely at the wiring diagram, I installed a jumper on the wires coming into the ignition switch and now the tach works again - and it runs great! Good luck.