Here is a image of my 80mm VDO tacho and it has three pinouts on the rear. 1 for +ve, 1 for Signal and 1 for -ve.

Does anyone know which is which? Google hasn't helped me so far.



VDO 80mm Tacho

I would just trial and error it but I am worried about shorting it out or something.

have a look here

http://www.etbinstruments.com/Wiring_Instructions.htm

I think you need the 100m guide looking at the picture you have posted.

PS I will post up regarding rough V8 running when I get Home

ATB Agriv8

Oh, feel a bit silly now. I have been to that website and downloaded the 80mm Electronic Tacho instructions as I have a 80mm tacho. The 80mm are different but the pinouts on the 100mm instructions look perfect - cheers