This will involve cleaning the cylinder head and related valve train components. Clean the entire cylinder head with solvent as well as the rocker arms, pivot balls, nuts, pushrods, valve springs, spring seats, rotators, keepers and retainers as well as the rocker arm pivot stud threads. After heavy deposits have been scraped off from valves use a motorized wire brush to remove deposits from valve heads and stems. Examine the cylinder head for cracks, coolant leaks and warpage; inspect valve seats for damage. Measure the stem-to-guide clearance of each valve and examine each valve face/neck and stem for wear deformation, cracks pits and burns. Also measure the margin width on each valve and test spring lengths for wear. Inspect rocker arm faces, pivot contact areas, pivot balls pushrod ends and rocker arm studs as well as spring retainers, keepers and rotators. If any parts are damaged or worn excessively replace them. Finally reassemble valves in cylinder head if they are in poor condition with some being out of limits due to wear of all valve components.