Tachometer reading too fast
 

I have a SW vintage mechanical tach that I had retrofitted by Classic Insturments. The unit is about 4 1/2 years old. All of a sudden, it is now reading about 1000 RPM higher and reads higher throught the RPM sweep. Nothing has changed and the car still runs fine. Any ideas before I send the unit back to Classic Insturments?

Thanks,
Tim

Sounds like noise in the system. Try switching the dip switches back and forth and then back to normal mode for your setting. Usually that does the trick for a climbing tach.

Try double checking the grounds on the engine and the gauge.