Fix that Tach

I just read Sublime79s thread about his tach problems. Here's mine. The tach floats at about 7gs when the engine is idling. As soon as I crack the throttle, the needle buries. The filter is in placce and If I jump out the filter and connect the tach directly to the distributor, it does the same thing.
I pulled the tach out and noticed that there is a spot on the tach board about the size of a dime that is light brown in color - doesn't look burnt - more like it was close to a bulb - although that may fit the description of burnt.

How many would vote to go for a new tach board?

Pass the W A V E ! !

Luke

Very well could be. Connect a tach to the tach wire on the dist. If it acts the same way as the one in the car, the problem is in the dist, but not likely.
If it works okay, go for the board.

My tach had a little different symptoms, and ended up needing a board and a new coil (not the ignition coil) Jason at Vette Instruments fixed it and I've had no problems since. He also fixed my temp gauge. Here is his e-mail if you are interested in contacting him, there is no website. VetteInstruments@aol.com

if you replace the tach board reset the neddle with the key on pull the neddle out and set o zero

After the issues with my tach I can only add the following. The light "burn" on the cicuit board is more than probably a burnt circuit board and not heat from a lamp. As you already have it in bits I would fit a new board, if it cures it then all is well, if the problem persists then at least you have eliminated that area and you can look else where. The new boards are not that expensive. Perhaps Ken could advise as to how you can check the original filter to see if that could be the issue, it is getting on in years now so you never know. Good luck.

You can use an ohm meter to check for flow across the filter, and make sure it is not shorted to ground. Then us a hand held tach. Check for a signal into the filter and out of the filter. If it's on both sides and the ohm test was good, it's okay.

Good news vette fans! Took a shot in the dark and went for the tach board. Turned the key and watched the tach report 600 rpm at idle and great response as I cracked the throttle. Thanks for all the ideas!!

Luke, how much and where did you get your new Tach.?

I actually only replaced the PC board on the original. They're readily available from most Corvette parts dealers. I bought mine from Corvette Paramedics in Mt Holly, NJ - well worth the $60 gamble. - It seems as though the board is the culprit, the more posts that you read.

Good luck, GOB BLESS AMERICA and Support Our Troops!!


Here's The W A V E !!!!!!!

hey luke

thats a nice looking vette... but please crop out the extra and resize it down to something reasonable like 320x240