When you are able to do some test and tune at the track you will want to increase the orifice size until 60' times start to slow down. You may find when you change something else (timing, jetting, tires, launch technique ect.) you can benefit by going thru another iteration of orifice size testing. Keep in mind that area changes with the square of radius so small changes can be significant.



1971 Factory Appearing Duster 340 11.000 @ 122 mph