Rev counter on a PV544

[morwenna240]

Hi. I want to install a rev counter on my pv. Instructions say signal wire on gauge to negative side of coil. Prob is, there only two wires on the "armoured" coil, the thick one to centre of dizzy an one thin one to side of dizzy. There are no marks on coil to say if is poz or neg. Advice please, all vintage auto sparks. Thanks.

[Rustinmotion]

Originally Posted by morwenna240

Hi. I want to install a rev counter on my pv. Instructions say signal wire on gauge to negative side of coil. Prob is, there only two wires on the "armoured" coil, the thick one to centre of dizzy an one thin one to side of dizzy. There are no marks on coil to say if is poz or neg. Advice please, all vintage auto sparks. Thanks.

Usually they need a +12v a negative and a connection to the coil terminal that goes to the distributer
It’s the pulse of the negative coil as it’s grounded by the points closing that’s used as the signal

[morwenna240]

Righty, ta. Will try connection to that terminal. I see u at MK., we used to live at Wavendon. Cheers.

[samaron]

The signal wire goes to the terminal that connects to the points on the distributor. This is the negative. The positive is hidden inside the armored wire that goes to the ignition switch inside the car.

If it is a modern multi-cylinder instrument that requires additional 12 volt power to function, it should still work fine on a 6 volt system if you have that.

If it is an old school instrument with two wires, then the "positive" goes to the coil negative, and the other to body ground.

[morwenna240]

Thanks Samaron. Tis 12v. New electronic gauge. ****ing down her, but might stop after tea, whereupon i shall nip out an test. Y'health, Mark.

[Derek UK]

With the GT gauge the tach signal wire replaces the wire from the neg on the coil to the dizzy as per this drawing. It counts the sparks going from the coil to the dizzy and divides it by 4. The pos on the armoured coil goes from the ignition switch to the underside of the coil.

[morwenna240]

I connected signal terminal on tach to visible wire dizzy to coil, works fine.
Thank you, people.