I'm glad I managed to help someone!
Makes a change from throwing sith lightning at my enemies!
One thing I would emphasise is that the way the original RVI tacho on dmblbit's P6 was wired; the tacho "sniff" connections were put between the 12v supply (the white pigtail wire with a female bullet) and the white wire with yellow tracer (with a male bullet) that goes and connects to the coil + terminal (via the ballast) (like FraserP6's car is, for example).
Other cars with RVI's (like Brian Northampton's car "Vanessa", for example) have the "sniff" connections between the coil - terminal and the points. I think the wires connected to the sniff connections is a white wire with slate tracer (
or white with black tracer) coming from the coil - terminal to a female bullet (which mates with the male bullet on the tacho), and then a white wire with black tracer (
or white with slate tracer) having a male bullet (which mates with the female connector on the tacho) which then goes to the points.
I cannot recall which colour tracer is on the coil - and which colour tracer is on the points connector on the distributor!
If dmblbit's car was wired like Brian's "Vanessa", it would have been easier in that there would no need to run an extra wire from the dash under the bonnet to the coil - terminal, and then the procedure would be:-
1) The wire with the female spade which powers the original tach (Is that also a white wire?) would also be connected to the male spade on the RVC tach.
2) There's a need to create a short three way wire, with two ends fitted with a female bullet connector, and the third end fitted with a male bullet connector. (Or two wires, one end of one of the wires fitted with a male bullet, the other end of the same wire fitted with a female bullet, and then the second wire pigtailing to a female bullet connector from one of the ends of the first wire)
a) The male bullet of the newly made wire mates with the female bullet on the white with slate (
black) tracer wire,
b) The female bullet on the newly made wire mates with the male bullet on the white with black (
slate) wire and,
c) The pigtailing female bullet connects to the male bullet on the RVC tacho.
I know you could cut into the insulation, then wind and/or solder a piece of wire, or even use scothloks. But 1) I think that's a bit of vandalism, and 2) in the case of scotchloks, I don't like them being used on an LT circuit because I've seen someone use them on an LT circuit and it caused lots of problems [though in this case of course the important LT current would not actually be carried/conducted by the scotchlok "knife" (that cuts through the insulation)]