Abstract: To greatly increase the size and thus the strength and life of the valve-closing spring of a high-performance (e.g. automobile-racing) engine, a rocker arm is employed to couple the much larger remotely located spring to the valve stem, from which was removed the smaller short-lived spring for which the much larger spring is substituted. The rocker arm and the substituted large spring are mounted on a base plate attachable to the engine-head assembly, and a cover shell is made removable for access to the parts, which include an adjustable-length spring-pressure-adjusting hold-down device.