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The tachometer on my P6 V8s has two plugs on the rear. That doesn't seem right to me. Before I disconnected it from the circuit board, it would sometimes fail to stay up or would operate intermittently. The Perspex display would function correctly if I touched it. I disassembled and reassembled the parts. The receptacle that takes the tachometer's bullet connector is movable. After ensuring a snug fit, I put the instruments back together. Now that it's fixed, it works reliably, although the readings are lower. At 30, 50, and 70 miles per hour, how much rpm should it show in fourth gear? We appreciate any help you may give us!

My friend's Rover's tacho is much like yours; it works sometimes and doesn't other times, and a quick touch on the Perspex screen will get it going again. It's been doing this for at least a couple of decades.

Since 4th gear has a 1:1 ratio, it will take 1250rpm to reach 30mph, 2083rpm to reach 50mph, and 2917rpm to reach 70mph. Therefore, little over 2000rpm and just under 3000rpm respectively for the later two.

Take off the glass cover and place a single drop of 3in1 light oil on the spindle of the RPM gauge.

I'm trying to figure out how to fix my own wobble, which I've decided is more of a twitch, over in a different topic. I've changed the oil and double-checked the rear connections and the coil end connection, but the problem persists.

Howdy, folks!
A similar issue has arisen with my Rover's rpm counter. It reads intermittently for a while, pauses, and then starts up again. A technician examined it and concluded that it was functioning OK, but that it would not be appropriate for use with Rover's electronic igination. When I initially got Rover, it always seemed to work, so I didn't believe him. After a little TLC, it's back to giving reliable intermittent readings again. So, my inquiry is whether or not it is compatible with the electronic ignition that the Rover uses.

The expert who works on your instruments probably has a point. Most electronic systems will render useless the RVI type gauge that was developed to count the impulses in the ignition low tension circuit when the points opened. It is possible to use circuit boards to upgrade to voltage sensing devices designed for use with modern electronic systems, but doing so is expensive unless you do it yourself. Close inspection of the tacho face should reveal the RVI and a corresponding number.

Hi. I appreciate the feedback. Inspecting the rev counter from the Rover I used to have in 1974, I saw that it was labeled RVC 2412/100. I was wondering if it could be converted to electronic ignition and whether it would be transferable.

The RVC variety is a voltage measuring tool, thus it should function well. However, you will need to modify the wiring to install a sensing loop and supply the instrument with 12 volts.

I'm looking into whether or not the tacho from a 1974 car will fit in a 1969 dashboard.
Thanks.

I was asked by Whiterover where he might get RVI-to-RVC conversion circuit boards. It looks like this may be a good place to begin.

Go here: http://www.ebay.ca/itm/Smiths-RVI-RVC-T... 0578001095 to purchase a Smiths RVI RVC T.