1982 Tachometer

[minifridge1138]

I just bought my first Corvette, a black 1982. I got it at a good deal because the previous owner had made some modifications. I bought it from Corvette Country in Austin Texas. They were very helpful, but that's a different story.

Anyway, the previous owner replaced the crossfire fuel injection with a Holley 4-barrel carb, holley intake manifold, and a mechanical fuel pump. Since i bought the car, the Tachometer has not worked. I have the Shop manual, and the diagrams show that the tachometer runs off of the HEI distributor, to a tachomenter circuit board, to the actual guage. When i start my car, the tach jumps to about 2k rpms, and slowly spins all the way past 8k and eventually pins the needle. It does this even if i disconnect the wire going to the HEI. A new circuit is about $200, but given the other modifications, i'm not sure if the circuit is the problem.

Does anyone have experience with the 82 corvette that might have advice about the tachometer? Would it be easier to just replace the whole thing with a mechanical one?

Any and all advice will be appreciated,
Thanks
-David

 

[bill81vette]

chances are it is the circuit board behind the tach that is bad..they are about fifty bucks to replace,you can get them at any of the corvette parts suppliers...

 

[minifridge1138]

thanks

Alright, i'll give it a shot. Is there any particular online parts store you recommend?

thanks,

 

[bill81vette]

I've had pretty good luck with corvette central...

 

[80convertible]

Before you go and order a replacement part, I would suggest checking your circuit board. It's really simple. Use a continuity tester and check that all of the circuits are intact... no broken copper. Since you own a vette you are going to need to learn to work on electrical anyways.

My tack stopped working a few years ago. I discovered corrossion on the copper tabs. The eraser from a pencil cleaned the copper tabs and the tach works perfectly. The lesson is to always start with the simplest and sometimes cheapest solution. It just may work and save you some money.

 

[minifridge1138]

Tach Circuit Check

That's a pretty good idea. How do you get the tach circuit out? If you've done it, then do you have any tips?

 

[80convertible]

That's a pretty good idea. How do you get the tach circuit out? If you've done it, then do you have any tips?

It's been years since I have pulled the gauge cluster. I hope my memory is accurate. Just some screws that hold the cluster in. The hardest part is getting the cable removed from the backside of the speedometer. You have to reach up from the backside of the gauge cluster while laying on the floorboard of the car. Not fun! Hope you don't have a bad back. Anyway, there is a clip on the back of the speedo that must be pushed in while pulling outward on the cable. The first time is always the hardest.

Remove any other wires or connectors to remove the gauge cluster. While you have the gauge cluster out check that all of your light bulbs are in working order. Visually check the circuit board for any breaks. You can then trace each circuit with a continuity tester to ensure that they are all working. My low fuel circuit board had failed only to discover that it just needed a small part reattached. Also, clean any exposed copper tabs (be gentle). I used a number 2 pencil eraser. Remember, your vette is getting old and as such the electrical system will need work and often times a good cleaning at the various connectors.

Jim

 

[LVMYVT76]

Sometimes there will be a burnt spot on the circuit board letting you know where the bad place is.

 

[jdp6000]

If you do find a break in the copper it is repairable. You can solder a wire to each side to complete the circuit.

Jim