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Is the scanner reading right? You should be able to which is right at idle, since there is a noticeable difference between 700 and 1400 rpm. I have never had a tach that read that far off, but I guess there is always a first. I would hook up an aftermarket tach and if it reads right, then your tach is bad.
Sid.
6 speed sid, you need to come join us at the track in jacksonville this thursday, its a ton of fun! send me an email if your interested.
as for the tach issue, i agree borrow a cheap tach, hook it up and see if it works in conjunction to your dash mount. if yes then something is very screwy. but most likely the calibration is off, im not sure how to adhust it but im going to learn! if you don't have it fixed by the time i figure out how to do it, i will drop you a line, in the measn time best of luck!
thanks for the come backs. i think i will buy a cheap tach and try it. i'm sure the scanner is right, you can tell the difference from 700-1400 rpm. and it sounds like the engine is turning 700 and not 1400. just needed to find out if anything could cause this before i buy another tach and find the same thing.