Clean the cylinder heads thoroughly and its related valve train components, removing old gasket material from the head gasket, along with sealing compound at the intake manifold and exhaust manifold sealing surfaces. Clear away scale buildup in the coolant passages and clean out via wire brush all kinds of holes as well as threaded holes. With a solvent wash down, completely dry cleaner rocker arm pivot stud threads, cylinder head, rocker arms push rods, spring retainers plus keepers, valve springs shields. The valves can be scraped to get rid of heavy deposits while the valve heads' epidermis can be cleaned free of deposit through electrically driven wire brushes. Examine for cracks in coolant wairs or warping. The condition of valves seating stem guide clearance faces spring wear retainers and covers end pivots are checked out for wear damage or proper installation by measuring margin width on spring seats as well as blade contact area between two adjacent rockers push rod ends bolted stud guide plates pull rods arm nuts studs are observed at every opportunity if broken replace them. For poor conditions reassemble valve parts into cylinder head: however for good conditions, reassemble them without major service operations performed on the same parts again.