Super Stock™ Cylinder Heads – Twin Cam – Black

High port flow gives great performance now, and more later when additional upgrades are done; Heads are fully assembled with springs and valves; Compression ratios vary depending on cylinder heads chosen, pistons used and engine displacement; see Compression Ratios chart for specifications; 79cc heads work great with stock motors for 88″ to 103″ motors; 89cc heads work best for motors over 103″ or with high-compression pop-up pistons; 79cc have 1.940″ intake and 1.575″ exhaust valve and springs for up to .650″ lift; 89cc have 2.000″ intake and 1.605″ exhaust and .640″ springs; 79cc heads accept OEM rocker boxes; 79cc and 89cc heads require S&S Lower Rocker Box Gasket Kit (0934-4574); Heads are machined for compression releases (sold separately); S&S rocker boxes required when using S&S compression releases; Do not include rocker arm components, intake manifold or gaskets; Heads include four long headbolts, and reuse four long OEM headbolts; Accept OEM intake manifolds; Made in the U.S.A.; Must use S&S rocker boxes (PART #90-4110) if S&S compression releases are used.