The altitude you drive in will have affect on the best tune, higher up likes more advance and leaner mixtures I ran my last pump gas street motor between 14.5 and 15.3 AFR at light ,part throotle cruise between 2100 to 2700 RPM in high gear. I could make the AFR change by pushing the throttle pedal up and down a small amount, which would not make the car go faster or slower Keep your mind open and look at the gauge and spark plags for the best tune, the AFR can be influence by the location of the sending unit, probe, gasoline, altitude and outside weather It is not uncommon on a lot of "peforamnce" carbs to go fatter on the transition circuits That can be fixed also Drilling and installing screw in bushings with smaller holes for the fuel to travel through The Carter and Eddy carbs are a little harder to do that to than the Holley are