[ted]

In reference to using Webers, the higher the duration then the greater that the lobe centerline that the camshaft must ground on. Where the camshaft ends up being installed in relation to the intake lobe centerline (advanced or retarded) is also a key player. Reversion back through the Webers becomes critical due to the carbs sitting on top of the intake valves and lobe centerline is the controlling factor over the overlap cycle that affects this. For this reason, lobe centerline angle is quite important.

On my own ride, the difference between 108° and 114° lobe centers was over half a second in quarter mile et with the Webers. The reversion on the 108° lobe centerline cam was quite obvious as the cloud of fuel coming up out of the Webers and then being pulled back down on initial acceleration was more than noticable.