Cylinder head bolts secure the cylinder head to the engine block, maintaining combustion chamber sealing. These fasteners are subjected to extreme temperatures and cyclical loading, demanding high tensile strength and fatigue resistance. Typically manufactured from alloy steel, they often feature specialized coatings for corrosion prevention and friction reduction. Torque-to-yield (TTY) bolts are common, requiring a specific stretch during installation rather than a fixed torque value. Variations exist including multi-angle tightening sequences and the use of washers to ensure even load distribution.