Can sombody explain to me what the power diffrence is between Hi lift, long duration, and hi lift AND long duration cams? Which type of cam makes the biggest diffrence? Thanks alot...

 

Your duration (more than anything else) affects the rpms that the power comes on. Longer duration, high the rpms. Lift really needs to be matched to the flow of the head. Just because you lift a valve farther, doesn't mean the head is flowing more. So, basically the way I see it is find the lift that matches your head flow. Then run a short duration cam for torque, long duration for high rpm HP. There are a lot of other factors including ramp speed, centerline, lobe seperation, etc that also need to be taken into consideration. Luckily you don't really have that many choices in ATV cams.