I just installed an autometer tach into the 64 malibu that I recently purchased. The tach lights up and moves, but when the car is idling it reads zero. When the car is reved the tach responds. I have the signal wire hocked up to the - side of the coil. I am running a Pertronix coversion in the stock distributor. Anyone have any suggestions?

I had a Sun tach at one time that acted weird. I had to use some sort of power converter module on it. Ended up going back to a mechanical tach.

Hey Geoff(sp), That isn't by chance an inline-6 is it, you would have to cut the loop on the backside of the tach to correctly calibrate. If 8-cyl. I'd check another tach real quick before getting a replacement. Sounds like bad tach.

By the way, cool web site. Love the cars, that blue 69 elco is sic.

Geoff,
Most problems like yours are caused by a bad ground connection. Make sure that the tachometer ground wire is attached directly to the engine block. I use one of the coil hold down bolts. Make sure that the blot and the metal it goes into is very clean also.
Hope this helps,

I recently installed a cheap autometer tach (fit nicely inside the clock hole).

It is not very accurate. I ended up trying to fiddle with a pot. that was mounted to the circuit board inside to try to tune it in a little more.

It might just be the quality of the tach components.

We just installed an Autometer tach on our 72 El Camino and it does the same thing. I took back one and got a second one. the second works a liitle while and then goes to zero at idle. I made sure the ground and connections were good.
RichF

I checked all the connections and they all seem ok. I am going to improve the ground as that may be the culprit, but I think that there is something else going on. I am pretty sure that the tach is not the problem, but I will test it on another car tommorow and see.

No input? I heard somewhere about some sort of diode or resistor, but have been unable to find any more information.