The tach on my camaro is off by like 500 rpms at idle and it gets worse as it goes up, like i have a 2.8 v6 and my tach will pin at 7000 and i still have rpms to go. Is my tach bad? is there some sort of adjustment? did my grandma who i got the car from have it rebuilt with 8000 rpm capabilities? probably that last one. what do you guys think?

http://www.thirdgen.org/techboard/el...aayyy-off.html (tachometer waaaaayyy off....)

Try this one, found using the search button.
There is another thread about the resister pack on the tach's going bad.
I had to fix the resister pack AND the capacitor to fix my tack. It was reading WAY off (resistor pack) and then it was only a little off (capacitor fix).
Hope this helps,,,
BTW...almost all third gens have at least one of these problems.
Your problem sounds like the resistor pack.