I have a problem with my tacho, it has been this way "forever" according to the 2 previous owners.

The tacho reads about 30% wrong. It idles in 500rpm, and rev limit is 4300 or so.

Its a SC400. Does anyone know of any fixes, or should I just get a 5" on the dash?

 

I had a problem with my tach, I just went to the junkyard, pulled another cluster and then swapped the tach motors. Worked perfect after that.

 

It is likely your stepper motor inside the cluster for the tach. Service will cost you around $100 to replace the motor.

 

Thanks. Ill look into that stepper motor!

 

Depending on if you have a 5 speed or auto you have either one capacitor or two controlling the tach reading on the tach motor. If one of the caps starts to dry up it can give incorrect readings. You can search my user id for a thread I did on the tach and speedo.