Dashboard Wiring, Speedo and Rev counter setup.

The dash comes with pre marked locations for instruments which is fine but I did it slightly differently.

I like the important lights and gauges together so I can see them all with one look instead of having to scan the dashboard. Also, when I hit the starter button, I want oil pressure information in my line of sight. The clock isn't a gauge so it is separated out between the two big clocks. Finally I wanted the row of switches higher up so easier to see/reach. The start button has a quite lovely chrome finish base which I thought was a shame to hide so I mounted it proud of the dash surface.


AK will supply diagrams and explanation sheets along with the wiring loom.
The detail on these sheets is all you need to correctly wire up the rear of the dashboard as well as the steering column, wash/wipe relays and connections into the main loom. But there are some gotchas.


I was going to mount the wash/wipe relays behind the wiper motor, but it meant changes to the main loom. I think the AK desire is to mount it with the other relays on the passenger side so I have drilled and tap'ed into the scuttle hoop and mounted them underneath the main relay cluster. The two connections from the wash/wipe cluster connect into the main loom and into the wash/wipe stalk on the steering column. There is a separate connection from the main loom into the wiper motor. There is an earth strap from the main loom to connect to the motor bracket and I have earthed the steering column here as well

Dashboard connections are well represented by AK's diagrams. There are some wires the same colour, three red wires for instance. Fortunately they come from different connectors in the short loom for the dash so just buzz them through with your AVO and compare to the list in the wiring instructions. The only thing that tripped me up is the fact there is a wire coloured blue/red, and another one coloured red/blue. This was far too subtle for me and I got them mixed up until I went back to basics, buzzed them through and reconnected them correctly.

If you have the usual Smiths instruments tacho and speedo (mine from S&J Motors) there are two options to connect the sensor. Use the black/white connection in both cases.
The tacho sensor comes from the blue/yellow wire from the Omex unit. There is a wire in the engine bay leg for connection if you have a distributor, either use that or, as I did, feed the wire from the ECU and connect it to the pink wire in he loom or straight into the black/white on the tacho.


A proper ratchet type crimp tool is worthwhile. Mount it in a vice to free up a hand to hold the wire and terminal.







The terminals on the switches are very small. The correct size connector is often too small to get two or more wires crimped when daisy chaining. On some of them I stripped insulation part way along the wire and crimped the terminal there, leaving the wire to continue onto the next connection.

Multi-coloured birds nest! This is temporary to get everything connected, tested and later to start the engine. It will have to come out when the dashboard gets covered, but I'm not too fussed if it isn't perfectly laid out. It isn't on show and the important bit is the robustness of the connections. On the right is the voltage stabiliser. The screw mount is used as a collection point for all the earth wires. It needs to be mounted with the arrow facing up. Apparently it won't work properly if not. So if you find yourself upside down in a ditch, you may not be getting a correct fuel level reading.


I started with connecting all the earth terminals. Once they are identified it is easy to know the other terminals which aren't easily identified on their own. I have used heat shrink tubes over the connections. I hate pre-insulated coverings that squash and look horrible after being crimped. It takes longer but I prefer to have a good look at the crimp, make sure it is good before covering with the heat shrink and apply a hot air gun.


So, connect the battery, have the gorgeous love of my life standing by at the isolator switch with instructions should there be smoke and fireworks, turn the ignition and, lo-and-behold, it all works. Lights, indicators, wiper motor noises, quite a loud hooter. Brake, fog, reversing lights, all present and correct. Thank you Mr. AK.

There are two things. First the indicators work with the ign switch off. I reckon that is so the hazard lights work. And secondly, the hi beam flash on the indicator stalk works with the ign off. Weird, but correct according to how the loom is wired says the Man. I can't think why you would want to be able to flash your lights with the ign off. Unless you happen to be parked up in a country lane or car park late at night. And I have no idea at all why that would be.

As we may be fitting the rev counter now, there is some work to do with settings. I have the classic Smiths instruments from Caerbont Automotive. At the back of the rev counter is a round rubber bung. Behind that is a bank of switches. There should be a leaflet with the rev counter that explains how to set the switches according to how many cylinders your engine has and whether it is has a wasted spark system or not. The configuration for an 8 cyl engine with or without wasted spark didn't work for me, the rev counter was not reading correct RPM. It may be a 'feature' of the Omex ECU but the setting that worked is for a 4 cylinder single spark. That is to say SW1, SW2 and SW8 = on.

From the same company comes the speedo. It will need setting up to at least have a reasonable go at reading true road speed. There are regulations about how accurate it needs to be and you need to acquaint yourself with that. However there is a basic setup we can do before testing it on a rolling road.

This Smiths speedo has two methods. We can set it while static in the workshop, or drive it for exactly one mile and set it accordingly.

The manual method.

You need the circumference of the rear tyre and to know how many inches in one mile, the diff ratio and the number of pulses from your speedo sensor.

So we take divide 63,360 inches by the tyre circumference and multiply that by the diff ratio. That gives us the number of rotations per mile. Multiply that by the number of speedo pulses per revolution and we get a number we can use to set the speedo.

So in my case:

63,360 / 80 = 792

792 x 3.54 = 2803.68

2803.68 x 12 = 33644

33644 then is the number to use on the speedo setup.

There should be a leaflet that describes how to set the speedo but basically hold the trip reset button in and switch on the ignition. Release it before the needle does a full sweep and it will enter setup mode. Set the number by pressing the button to increment each number, then switch ignition off.

That should do until we get it on a rolling road and see how it worked out.

By the way, if you find the trip button not working properly, it will most likely be because the good people at Caerbont have soldered wires to two thin terminals at the back of the button but then left them bare inside a heat shrink covering. If the terminals get bent during installation, and they probably will, they end up shorting out. I had to cut the heat shrink away and then properly insulate the two terminals from each other.