S&S® Super Stock® 3-5/8" Bore Band Style Single Plug Cylinder Head Kit for 1979-'84 Big Twins - Natural Aluminum FInishS&S Super Stock band style cylinder heads for 1979 '84 HD big twins feature a stock like appearance, but flow much better than stock heads. Heads come assembled with premium valves and S&S valve springs that can handle cams with lifts up to . 590". These heads are machined for one spark plug per head and accept 3 5 8" bore cylinders. These cylinder heads are original equipment on S&S SH Series engines, and are a great upgrade for stock shovelheads.