Regardless of whether or not the head was sent to an automotive repair shop for valve servicing, make sure it's clean before beginning reassembly. If the head was sent out for valve servicing, the valves and related components will already be in place. On all engines, lubricate and install the valves, then install new seals on each of the valve guides. Using a hammer and deep socket, gently tap each seal into place until it's seated on the guide. On OHC engines, reinstall the valve lifters. Beginning at one end of the head, lubricate and install the first valve. Apply moly-base grease or clean engine oil to the valve stem. Drop the spring seat or shim(s) over the valve guide and set the valve spring, retainer (or rotator) and sleeve (if used) in place. Apply a small dab of grease to each keeper to hold it in place. Compress the springs with a valve spring compressor and carefully install the keepers in the upper groove, then slowly release the compressor and make sure the keepers seat properly. Repeat the procedure for the remaining valves. Be sure to return the components to their original locations - don't mix them up! Check the installed valve spring height with a ruler graduated in 1/32-lnch increments or a dial caliper. If the head was sent out for service work, the installed height should be correct. The measurement is taken from the top of each spring seat or shim(s) to the bottom of the retainer. If the height is greater than the figure, shims can be added under the springs to correct it. Caution: Don't, under any circumstances, shim the springs to the point where the installed height is less than specified. Apply moly-base grease to the rocker arm faces and the fulcrums, then install the rocker arms and fulcrums on the cylinder head studs.