I have recently gotten my long term project running and the tach reading is off by about 1/2. I did change the distributor while I had it apart because my old one was toast but the new distributor was also out of a v-8 TPI. My car is an 89, I dont honestly remember what year the other distributor came out of. Was there a difference in years? Suggestions on how to fix this?
Thanks
Roy

 

You might want to take a look at the filter capacitor in the base of the distributor.