These cast pistons are used in S&S Sidewinder® kits for knucklehead, panhead, and shovelhead engines, as well as in complete S&S engines for 1966-' 84 Harley-Davidson® shovelhead models. These pistons are used for 4-1/4" and 4-1/2" stroke engines with stock diameter (8-1/2") flywheels, and for 4-3/4" stroke engines with 8-1/4" diameter flywheels. 3-5/8" bore, +.070" oversize.
