well? car is a 79. ive seen a couple 83-84-85 tachs that dont work well when cold, this one reads about double what its supposed to. is it something else maybe?

 

Perhaps it's not effectively switching from volts to tach?

 

it could be, now the question is why would it do that?

 

You have an aftermarket to test it with?

 

nope only an oem

 

bleh, Id say pick up a cheap one from (insert random autoparts store here) and try it out. Then take it back and get a refund once you know the results.

 

did you pop the hood and make sure it doesn't have a v-8? It happens.

 

nope factory engine

 

Most autoparts stores here have a return policy on electronic parts. If it's 'installed', you can't return it for a refund.



Do you have a dwell/tach meter handy? Does the car still have points? Or has someone butchered in an FB electronic dizzy?

 

its still got points, i put the dwell meter on it, and the dwell meter says 800rpms, engine sounds like 800 rpms, tach in the car is at 1600ish, we're thinking a diode or something went bad in the tach.