1/4 MPH---106.03 that's should be good for mid 12's easy. I'm inclinded to thing you have a timing-carb issue. Use a vacuum gauge to tune your carb. Even w/ a 509 cam you should be able to get 6-8 at idle. Do you still have a choke on the car? I've seen them suck shut or at least restrict air flow. What are you shifting at?
