On 2.7L engines only, remove the balance shaft assembly. Use your fingernail to feel if a ridge has begun reassembly. If the head was sent out for valve servicing, the valves and related components will already be in place. Begin the reassembly procedure by installing new seals on each of the valve guides, ensuring that intake and exhaust valves have different seals and are not mixed up. Gently tap each intake valve seal into place until it's seated on the guide, using a deep socket and hammer, but avoid hammering on the valve seals once they're seated to prevent damage, and do not twist or cock the seals during installation. Starting at one end of the head, lubricate and install the first valve, applying moly-based 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 and retainer in place. Compress the springs with a valve spring compressor and carefully install the keepers in the upper groove, then slowly release the compressor, ensuring the keepers seat properly. A small dab of grease can be applied to each keeper to hold it in place if necessary, as the small valve stem keepers are easier to position when coated with grease. Repeat the procedure for the remaining valves, ensuring that components are returned to their original locations. Finally, check the valve spring installed height using a dial or vernier caliper for the most accurate measurement, confirming the distance from the top of the seat/shims to the top of the shield or the bottom of the retainer.