how does a tach function?

[htchbck]

From what I can understand, a tach basically just finds out how often the motor fires (I'm guessing it finds this out from the disty or coil) and converts that into RPMs. Correct me if I'm wrong, but wouldn't that mean that an Escort GT tach would be able to give an accurate reading if connected properly to festiva? I don't want the whole cluster just the 7000RPM redline tach.

[jeffdjeffd]

On the Festiva at least, yes, it gets the signal from the coil (+)

[htchbck]

thanks, thats what I need to know... now all I need to do is get my car running...