Jock itch (tinea cruris) is a fungus, the same one that causes athlete's foot and scalp ringworm. The groin area is the perfect place for the fungi to grow and cause a fungal infection because it is moist, warm and dark.
The camshaft lift is the resultant net rise of the valve from its seat. The farther the valve rises from its seat the more airflow can be provided, which is generally more beneficial. Greater lift has some limitations.
Unlike many modern engines, in which the camshaft rotates on top of the rocker arms to control the valves, the 351 instead features a single camshaft in the center of the engine block and a number of lifters and pushrods to actuate the valves. As the camshaft rotates, it pushes a lifter upwards.