I put a Trisco tach ($25) in my 1990 Chev truck that has a 350 motor. I had
the tach on 8 cyl mode but it was giving me high readings, about 600 rpm too
high at 60 mph and the needle bounces around abit. Put the tach in my
daughters car (1994 Sundance) and it works fine.
Do some tachs only work on certain vehicles?