AutoMeter tach?

[bluebeast]

i installed my autometer sport comp tach on my car. i followed the directions how they told me to BUT i have a problem. When my car is idling the tach reads about 3k as i go the tach jumps all over the place until my stock tach reads 3k then the autometer one jumps down to 3k and works fine until i go below 3k. Basicly anything below 3k my tach goes nuts. any ideas on what could be wrong. i also have a whole jacobs ignition thing kinda like the msd but jacobs i also have a jacobs ultra coil. The instructions only mention the msd.
thanks
eric

 

[Black331Stang]

probably not what u looking for but only discrepancy i have invloving 3000 is that i cant set my shift point any lower than about 3400. i dunno if its normal or not

 

[Sgt.5point0]

I don't know a lot about the aftermarket ignition products but I think some of them have a specific spot on the box that you're supposed to run you tach signal wire to instead of the coil.

 

[88stangmangt]

are you sure you have it set for a v-8 rather than a 6 or a 4? they send out diff igniotn signals.

 

[Sgt.5point0]

are you sure you have it set for a v-8 rather than a 6 or a 4? they send out diff igniotn signals.

Thats true also... I think on the Autometers you have to actually cut wires at the back of the tach to go down in cylinders. I hope you didn't do that

 

[bluebeast]

nope i did not cut any of the wires on the back. it is set up for an 8 cyl. could it be my ground? do u have to ground it to the engine like it says?

 

[Sgt.5point0]

Yeah you could try moving the ground... If it does the same thing when you move the ground then that's probably not whats wrong. Did you check your Jacobs Ignition for a tach outlet?

 

[88stangmangt]

ya you might need a tach driver.