New and rebuilt cylinder heads are commonly available for most engines at dealerships and auto parts stores. Some specialized tools are necessary for the disassembly and inspection procedures, and replacement parts may not be readily available, making it more practical and economical for the home mechanic to purchase replacement heads rather than disassemble, inspect and recondition the originals. On 7.4 liter (454 cubic inch) engines, two head designs are generally available-"open chamber" and "closed chamber." These heads will interchange as far as bolt patterns, accessory mounting, etc. is concerned, but the different combustion chamber designs require different piston dome shapes. If you're purchasing a set of reconditioned cylinder heads, make sure the new heads match the combustion chamber design of the originals. Cylinder head disassembly involves removal of the intake and exhaust valves and related components. If they're still in place, remove the rocker arm nuts, pivot balls and rocker arms from the cylinder head studs. Label the parts or store them separately so they can be reinstalled in their original locations. Before the valves are removed, arrange to label and store them, along with their related components, so they can be kept separate and reinstalled in the same valve guides they are removed from. Compress the springs on the first valve with a spring compressor and remove the keepers. Carefully release the valve spring compressor and remove the retainer or (if used) rotator, the shield, the springs and the spring seat or shims (if used). Remove the oil seal(s) from the valve stem and the umbrella-type seal from the guide (if used), then pull the valve out of the head. If the valve binds in the guide (won't pull through), push it back into the head and deburr the area around the keeper groove with a fine file or whetstone. Repeat the procedure for the remaining valves. Remember to keep all the parts for each valve together so they can be reinstalled in the same locations. Once the valves and related components have been removed and stored in an organized manner, the head should be thoroughly cleaned and inspected. If a complete engine overhaul is being done, finish the engine disassembly procedures before beginning the cylinder head cleaning and inspection process.
