[Howard H]

Dave:

I ran into a similar situation when I recently installed a Crane XR700 ignition system. The instructions say to connect the tach wire (black w/ purple) to the "-" terminal on the coil. No tach. I also hooked up my dwell/tach meter to the coil to see if I could get an RPM reading, nada.

During a series of calls to Crane's tech support line, I got the following suggestions --- install a 10K ohm resistor between the "-" coil terminal and the tach wire --- increase the spark plug gap up to .045" --- make sure that there is at least 10.5 volts at the "-" coil terminal. Unfortunately, non of these suggestions cured the problem, and it looks like the final solution may be to purchase a tach adapter that they sell (naturally).

The bottom line here is that the OEM tachs don't seem to interact well with the newer high energy ignitions systems. I would suggest that you disconnect the wire to the OEM tach and hook up a dwell/tach meter. If you're not getting a reading on the meter, you can rule out problems with the OEM tach and the related wiring. Then, pump the Mallory people for all the suggestions you can get. If none of them work, you may be forced into an aftermarket tach. I think that some other guys here on the bbs could make some suggestions on VDO and other tachs.

Best of luck, and congratulations on your just about completed restoration.

Howard