C3 Tachometer

[Ray Morey]

My tachometer on my 79 has decided that when I start the engine , it goes from the 500 rpms where it sits when the engine is off, to go to below zero. The plug is connected at the distributor. Is this a function of the filter on the manifold, or the electronic circuit board?

[KEN BUTCHER]

Re: C3 Tachometer

Hi Ray, as far as I know the tach, when engine shut off, the needle sits between 500 & 1500 RPM. When you turn the ignition ON, but don't start the car the needle should sit at zero. If it goes below the zero, then the needle has to be taken off and reset (which is easy). If the tach is not keeping the proper revolutions then it sounds like a new print board is needed.

Ken.

[Ray Morey]

C3 Tachometer

Thanks Ken- since the needle isnt moving at all when the engine is running and stays below zero, it sounds like you would say that it is the circuit board. Is that hard to replace? Looks like Dr Rebuild sells them for about 70 bucks