I just got a tacho, secondhand goes to 10k rpm woo. And I know that there are 2 wires for the light (guessing + and - for power) and there is a + and - for the tacho and a trigger. Now I've been told that the trigger is connected to the ignition coil (where? around the screws) and the - to an earth (does that mean any earth, like the body of the car) and + to the + cable or battery) is there an easy wire to get the + off? Don't have any mounting bracket so not sure how to mount it yet.

Would help if we knew what brand, or what it is off...

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

It's a smiths, made in the UK. I know which wire is for what, I just need to know where ?I get the positive from, how I feed the wires to the coil through the firewall (must be a hole for other wires.

Does it have a cable loop clamp on the back- a little square nylon block? If so it's an early current sensing one, and has to be in series between the coil (-) terminal and the points wire.

If no cable loop clamp and it's just got (+) and (-) on it then connect these to the (+) and (-) coil terminals. Thats how most tachos are connected these days.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

It's got a little 3 prong like a plastic conector goes on it. there's a little diagram on it that says what they all are, it says red +ve, black -ve and blue trigger. There is another 2 wires which are white and red and I was told these are for the light.

They're called Smiths "MaxHand racing" tacho btw, I think. Doesnt it have an external bulb holder or atleast a round hole for the bulb holder?

The negative for the tacho and the ground for the light are separate in any case and you can ground the light anywhere (just ground it to the screw which attaches it to the dash or something. The positive for the light can either be connected to the existing light wires for other dash instruments so the light would go on when your lights are on or just to your ignition switch - on on ignition tab - to go on when the ignition is on.