Note: The guage came from a 1979 Rover SD1 V8 engine and was installed into a 1979 TR7.

The sender and pressure switch

The sender unit fitted to the V8 is electrical and seems pretty good. Coming from this unit are wires that connect to the engine loom and terminate in a small plug on the left hand side of the car (when viewed from the front). On my car I used this plug along with the its mate from the SD1 and soldered all my engine wires to this. On the SD1 the oil pressure sender unit and pressure switch comprises three wires and these feed 3 things: the oil pressure warning light, the oil pressure gauge and the fuel pump. I have since discovered that this is only true of Carb cars and I hear that the Injection cars have only one wire here (cannot verify the truth of this at the moment though).

The gauge

Remove the gauge from any V8 SD1 or buy separately. Some people dont like this gauge but it is cheap and redily available and fits. Remove complete instrument cluster from TR7/8 remove clock and take off clock fixing bracket. Shorten the depth of this bracket and remake the fixings so that the oil gauge when fitted to this bracket will be the same depth as the clock used to be (ie. The same as the other instruments). You may need to drill one of the mounting holes larger so that when fitted the gauge doesn't short itself. Alternatively make a new bracket in alloy / plastic etc.

Drill a hole in the back of the instrument cluster (white plastic) or find a way to get wires in and out of the dash without them showing.

Take the black instrument finisher and fix a small blanking plate over half of the hole the clock came out of. This plate should be matt black but will not need to say 'Oil' as the gauge has this written on it.

Assembly is the reverse of removal (always wanted to say that!!!)

Wiring

This is the easy bit! Now check out the Schematic and follow the instructions below.

The gauge has three terminals and when viewed from the back as follows: Right terminal is connected to the feed from the sender unit. Middle or bottom terminal goes to an earth point on the car body etc Left terminal takes from the white wire under the speaker grill on the dash top. This was connected to an old heated rear window switch (unused on my car - its a convertible) wire. This is also connected to the white wire that comes from the oil pressure switch and not the white / purple as this is the one that powers the fuel pump and the oil pressure warning light.

I hope this is enough info to do this job. Its pretty easy if you have a carb car like mine as the wiring colours will be the same too. Enjoy and let me know how you get on.

--Jon Wallis
Jon.Wallis@postoffice.co.uk