[jstobo]

I did not hook it up, but on my Zenith conversion I ran the tach output from the MSD to the RPM transducer where the black/purple wire plugs in. This is a nice square wave 12 volt signal. I tried this signal because in wiring the MSD I disconnected the signal that goes to the transducer from the stock CDI box as my tach needed the RPM adapter from MSD to work. You could probably tie in the crane trigger also, in my case another wire from the points and tach adapter, but the MSD tach signal was so easy to wire up. It's funny. The MSD tach signal would not drive my tach but it worked on the RPM Transducer and also on my handheld Tach and Dwell meter. Go Figure.

You need to wire the transducer to a RPM signal because the 12 volt output to the microswitch occurs at 1350 RPM and higher. Without an RPM signal the transducer thinks it is less than 1300 RPM and will not send 12 volts to the microswitch. I went through this wiring testing because I thought I was getting too much backfiring. Turned out I had a vacuum leak on one of the carb hoses. Tough to see. Now all tuned up and no backfiring. I kinda miss it though. Check for some vacuum leaks. It may be most of your problem. Hope this helps.