M311 273cc LS3 Cylinder Heads (SET)

Fully CNC ported, 68cc chamber volume 273cc intake port, 112cc exhaust port and 11° valve angle High Quality Components: Black Nitride Stainless Steel Severe Duty Valves Custom PAC .700” Lift Valve Springs Titanium Retainers O-Ringed Exhaust Ports (Hi-Temp Silicone O-rings Included) 2″ Headers Recommended Sold Per Set Billet rockers stands Included for use of stock  ls3 rocker arms  Items will ship from manufacturer  Specifications Description Specification Part Number Min. Bore Dia. 4.000” Intake Port Volume 273cc Exhaust Port Volume 112cc Combustion Chamber Volume 68cc Intake Valves FED Prime Grade Stainless Steel 2.165 913005 Exhaust Valves FED Prime Grade Stainless Steel 1.600 913007 Valve Springs .700″ Lift FED exclusive by PAC 914005 Retainers FED Titanium-64 – LS Dual Spring 914040 Valve Locks GM Valve Lock 916051 Valve Seals U.S. Seal – Viton High Heat Seal U.S. Seal 805 Billet Ro