Part Number: EDL-61459 Cylinder Head Style: Assembled Cylinder Head Material: Aluminum Cylinder Head Finish: Natural Combustion Chamber Volume (cc): 110 CNC-Machined Combustion Chamber: No Intake Runner Volume (cc): 290cc Exhaust Runner Volume (cc): 110cc CNC-Machined Intake Runner: No CNC-Machined Exhaust Runner: No Combustion Chamber Style: Open chamber Intake Port Shape: Oval Intake Port Location: Standard Exhaust Port Shape: Round Exhaust Port Location: Standard Intake Valves Included: Yes Intake Valve Diameter (in): 2.250 in. Exhaust Valves Included: Yes Exhaust Valve Diameter (in): 1.890 in. Valve Springs Included: No Damper Spring Included: No Retainers Included: No Locks Included: No Valve Stem Seals Included: No Rocker Arm Studs Included: No Rocker Arms Included: No Rocker Arm Nuts Included: No Guideplates Included: No Accessory Bolt Holes Drilled: Yes Valve Guides Included: Yes Valve Guide Material: Manganese bronze Valve Seats Machined: Yes Valve Seat Machine Style: 3-angle Valve Seat Material: Ductile iron Steam Holes Drilled: No Oiling Style: Through pushrod Machined for O-Ring: No Heat Crossover: No Quantity: Sold individually. Notes: Designed for Marine use. The spark plug location has been moved .150 inch closer toward the bore center. Custom pistons are recommended make sure to check clearance before final assembly Top-end marine performance. Designed for 396-502 c.i.d. big block Chevy engines, these Edelbrock cylinder heads include heavy-duty exhaust valves that provide the added durability needed for marine applications, and have one-piece, stainless steel intake valves with hardened tips and swirl-polished heads. The high-velocity flow capabilities of Edelbrock Performer RPM cylinder heads provide increased torque across a wide rpm range that's ideal for marine use. They're cast from A356 aluminum and heat-treated to T6 specs. Their oval-port heads have 110cc chambers and their rectangular port heads have 118cc chambers. Both the oval and rectangular port heads are hard-anodized to protect the aluminum in the harsh marine environments