Not sure which thread to post this under as there are two running along the same lines. I have been experiencing problems with my Smiths RVI tach on my 71 Sprint. When I purchased the car it had electronic ignition installed and the tach needle was bouncing all over the place, a common problem. I removed the luminition ignition system and reinstalled a set of points. This cured the problem. I have since replaced the wiring loom and wired according to the wiring diagram. All works OK but the needle is still not quite as stable as it should be and tends to bounce from time to time. The diagrams posted by ardee_selby are very helpful but do conflict with the Lotus wiring diagram. The Lotus diagram shows the feed from the ignition switch passing through the tach sensing coil via the anti theft switch on to the coil. the other side of the coil then goes to the distributor. The two diagrams at the top of page 1 show two Smiths RVI tach's. The one I have fitted is the first one but the Lotus wiring dia shows it connected as per the second one.
Which is correct as I am now pretty confused