I have a 89 RS with a 305 that's been swapped to a carb. Ever since I got the car the tach starts around 1500rpm and increases slowly and consistently all the way to 7000. It rises slow enough that it hits 7000 after around 15 minutes of driving. It doesn't seem to be effected at all by the actual rpm of the car and bounces around a lot. Any ideas what could be going on?

 

Tach issues are very common with our cars. I recommend you read this thread and then contact Greg for the next steps. He will likely be able to help you - he did a fantastic job on my '89 tach.

https://www.thirdgen.org/forums/interior-parts-sale/745154-new-90-92-v.html