tach attack

I wasn't sure what section to put this question in
but I'm going to try here first. My tach currently doesn't
work, but when I first start the car the needle moves
slightly. Can anyone help me with this or even maybe tell
me what might be wrong?
thanks,

tach-less john

John I can probally point you in the right direstion, but I don't know the way to check the tach. With your vett being a 79 its a electrical tack, ans with the needle moving when the ignition is turned on, I guessing its just a bad electrical connection. The first connection and easiest is at the distributor, check that wire that plugs into the tach port of the HEI. if that looks ok then that wire I assume goes back into under the dash to the tach. There also a bad connection, or possibly a poor ground. If you don't have a repair manual, might be a good time to get one. They have trouble shooting sections in them and also electrical section on how to trouble shoot these kind of problems. There may be a way to hood a multimeter to the tach output of the HEI to see if the signal is getting out, then you would chedk aat the tach , if that all was ok there also may be a way to induce voltage to the tach to see if the gauge is good. Hope I steered you in the correct direction, I'm sure I'll get corrected if I'm wrong, it was a educated guess casue I have the old mechanical tach drive, yeh I'm old..........

Dave
Mr69vett

Have you fixed or found the tac problem. I had the same problem and I ended up replacing the circuit board on the back of the tac. I purchased a replacement board from Riks corvette. You have to just about disassemble the drivers console to get it changed, but in the long run it is worth it. Let me know if you are still having problems with it.

Like Bill I also replaced the circuit board when my tach went out just after buying the car. You could plainly see where a resister (or whatever) had blown out and scroched the board.

Corvette Central had the best price I could find at the time (about $60.00 if I'm not mistaken). And he's right, the dash has to come off, but that's the joy of ownership.