Tachometer reads too high

This is surely an old question but as a new member is new to me. I have a '66 Barracuda with a tachometer. It has been refurbished, all wiring checked and properly connected, etc. When running the tach swings all the way over to the highest reading and stays buried there. What needs to be done? Thanks.

jwcuda1


Turn down the idle screw..................LOL

Sorry, had to say it :banghead: