What are opening and closing ramps on a camshaft profile and why are they so important? Why do we use nested or beehive valve springs? When is it best to use pushrod valve actuation or DOHC shim-under-bucket tappets or finger followers? Should we drive cams with gears, chains, or belts? Technical Editor Kevin Cameron and Editor-in-Chief Mark Hoyer (but mostly Kevin...) talk about the intricate details of opening and closing valves and different types of drive systems.