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I've just purchased this Smiths Rev counter for my 1964 Morris Cooper S and I need a little help to install it. Is there a wiring diagram available and do I need to look for the plastic socket the gauge would of have when new or just put a couple of connectors on the spades?

Hi. this link might help.

http://mk1-performance-conversions.co.u ... trical.htm

I have not seen that particular tach before. Its use of three spade lugs is a bit different. I will make the following suggestions. Consider them educated guesses based on the more traditional impulse tach wiring (as shown in the links posted by InimiaD). I suggest you try the wiring below with an inline fuse of about 5 Amps rating in the Red wire... just in case. Remove the fuse permanently from the circuit once you know the tach and wiring work.

As a sanity check, use a multimeter set to read resistance or continuity to measure the resistance between the tach terminals marked Red and Blue. There should be almost no resistance (a dead short) between the two. If the Red/Blue connections are "open" (infinite resistance between Red and Blue) post back.

You do not need the special plug but you will want to use insulated crimp terminals on the wiring.
The terminal marked "Black -VE" suggests that the gauge is for negative earth vehicles. Don't use this if your car still has positive earth. The black wire terminal should be connected to your car's chassis.
The terminal marked "Red +VE" would be connected to a +12V switched supply (the white wires leaving the ignition switch).
The final terminal marked "Trigger Blue" would go the Coil (+) terminal (the one that probably has a white wire on it now). Remove the existing white wire on coil (+) and tape it off so it cannot short to earth.

RVI tachs sense current pulses, not voltage pulses. They are wired in series with power flowing through the ignition coil. Therefore, the existing power supply is disconnected from the coil and this RVI tach is installed between the ignition switch and coil (+). Current flows from the ignition switch, in the Red terminal, through an induction loop inside the gauge, out the Blue terminal, and off to the coil. Once at the coil the path to earth is through the normal path, coil to breaker points to earth. The tach gets power for its electronics on the Red terminal and uses the Black terminal as an earth for the electronics.

Once you have seen that this wiring works, remove the fuse and fuse holder from the circuit. Ignition systems typically were not fused and this is just another component to fail and make future troubleshooting problematic.

InimiaD,
Thanks very much for the link, that is nice to see a physical brochure as I received no paperwork with the Rev counter.

Doug,
Thanks for the very detailed explanation on getting this properly connected in my Cooper S.
I converted to Neg Earth many years ago so with your help hopefully I can get this installed with no trouble.
I purchased this tach in lui of the usual Smiths unit I've seen just about everywhere after seeing it in Parnell's Cooper S original series book and I wanted something different.
I'll post back and let you know how it works out, thanks again.