is my tach going bad?

[Curtis]

Most of the the time the tachometer appears to be accurate, but at times it reads way too high... even at idle it can read high as 1100 and if you touch the gas it jumps way up real fast.. Is the tach going bad or is there a connection problem somewhere?

 

[dmdodd]

Sounds like it's a common problem:

http://www.corvettemagazine.com/2005/june/tach/tach-lead.asp

Click on the subtle link top-left that says "continue" to go to next pages.

My tach pesonally gets to 2200 RPM everytime then sits there even though the revs are obviously increasing above that. It works fine below 2200, but almost hits a barrier and stops there.
I'll probably have to replace this circuit board too, as it ain't good not knowing what your tach's supposed to be showin!