AFR’s 200cc SBC Enforcer Cylinder heads feature our Permanent Mold “As-Cast” Technology. These heads are a good pick for a 350 to 400 Cubic Inch operating below 6000 RPM. A356 aluminum/69cc chambers/angle plug/23 degree/min bore 4.000”/ 8mm stem diameter bead lock keepers 21-4n stainless steel Int/exh Valve 2.050″/ 1.600″ Melling Racing Spring 1.290″OD Hydraulic Roller Dual Valve Spring, 140 lbs on seat, .600″lift, Max RPM 6500 7°Chrome Moly Retainers 1.245″ O.D x .885″ I.D x .655″ I.D 7°Bead Lock Valve Keepers ARP 3/8″ Rocker Studs Adjustable 5/16″ Guide Plates Viton Valve Seals Hardened Valve Spring O.D Locator. Spark plug use Autolite 3924. Special order 5-7 business days. Please e-mail with questions. (Item in picture may be different than actual product.)