Fitting the complete Cortina loom, but adding a Jaguar (Smiths) Rev counter.

How do I wire it to the engine?

You should find 4 connections on the back of the taccho

+ve, -ve and a pair of connections that form an inductiver loop -- the coil loop connects through the loop.

Be aware a Jag tacho won't read correctly on a 4 cylinder car,

Found a lot on getting a 6 Cyl Rev counter to work on a 4 Cyl. Always does a search before I ask a question.

This is what the Rev counter looks like. What termonal gets connected with what side of the coil?
Rescued attachment Rev Rear.JPG

That looks a little on the old side, would have thought that the terminal connected direct to casing is earth , the one opposite would connect direct to coil neg terminal IF tacho is neg earth. hope this is of some help, Rusty

There is actually 2 terminals on the RH side. A spade and a round one.

What is the negative side of the coil? One wire comes from the loom and the other goes to the distributor.
Rescued attachment Rev Rear 2.JPG

The neg side of the coil should be marked with a neg --- or possibly a number 1 . Sorry didn't see the 2nd terminal , the second photo helps, might be worth trying each? Rusty