These S&S® Super Stock® cylinder heads are a direct replacement for original equipment heads on S&S® V100 4" bore engines for 1984-'99 HD® Evolution® Big Twins. The 84cc modified bathtub chamber is designed for a flat topped piston. Large 2.000" intake and 1.605" exhaust valves and high flowing ports supply plenty of air for big inch engines. Compatible with cams with lifts up to .650". Machined with the S&S® 4" cylinder stud pattern. (Not for stock crankcases). Natural aluminum finish.