S&S EVOLUTION BIG TWIN PERFORMANCE CYLINDER HEADS

Exactly the same cylinder heads as S&S uses in their complete 1,340cc/80CI V-Series engines. Feature 1.9" diameter intake valves and 1.605" diameter exhaust valves and give increased flow compared to stock Harley heads. These cylinder heads can be used with stock 3 1/2" bore, as well as 3 5/8" Big Bore with stock style flat topped pistons. The version with 82cc chamber give a 8.4:1 compression where stock heads give 8.5:1 compression. Heads with 76cc chambers give a 8.8:1 compression. Valve springs are compatible with up to .585" lift cams. Heads come with valves and valve springs installed and are sold in sets for front and rear.