The clearance ramp on a mechanical lifter lobe has no effect at all on total lift, which is a function of the diameter of the base circle compared to the height of the lobe. Exhaust lobes have a wider clearance built in to accommodate the fact that exhaust valves run hotter than intakes, and the stems grow more at normal running temperatures. A "clearance ramp" is an area of slow, gradual lift just off the base circle designed to stack all the valvetrain parts together slowly before the lobe slaps the valve open pretty vigorously. Hydraulic cams also have acceleration ramps, but they're very short and they only lift 2 or 3 thousandths before the rapid lift begins. There's a corresponding slowdown area at valve closing to keep from battering the valve seat as the valve approaches, and then the clearance goes back in on the solid lifter shaft to reestablish the clearance. Different cam grinds have different amounts of clearance built in, so always use the manufacturer's lash specifications on a non-stock cam.
Higher lift on an exhaust valve usually develops more low-end torque, so solid lifter cams designed for use with standard-transmission applications probably used more exhaust lift to help with acceleration away from a stop. The hydraulic-lifter engines were originally used with torque converters and automatic transmissions, so the issue of breakaway torque was probably less critical since the torque converter essentially doubled engine torque when pulling away from a stop.
Jerry
