i have a 78 L82 four speed, when the car is running the tach works fine when it is turned off the tach stays around 1000 , any help would be appreciated thanks mytoy

 

I guess you have never owned a boat with a tach on it. It is a "common" thing for a tach (with the switch off) to NOT return to zero..........such as a speedometer.

You say it's working OK when the car is running!? Why should you get concerned where the needle is, when the car is just sitting there, engine off????????????????????????????????????

 

Hi mytoy, welcome to the site. The tach on your year is an electronic unit that gets a signal from the HEI distributor when running, when you shut it down the tach will not normally go to zero, after the engine stops turn the key back to the run position, the tach should then rest at zero RPM, when you turn the key to off the tach will again find an irrelevant resting spot, this is normal operation.