Cylinder Head Specifications; Combustion chamber volume: 16cc; Intake runner volume: 215cc; Exhaust runner volume: 115cc; Intake valve diameter: 2. 19; Exhaust valve diameter: 1. 72; Valve stem diameter: 11/32; Valve guides: Manganese bronze; Deck thickness: 9/16; Valve spring diameter: 1. 55; Valve spring maximum lift: . 600; Rocker stud: 7/16; Guide plate: Hard ended steel; Pushrod diameter: 3/8; Valve angle: 0°; Exhaust port location: Stock; Spark plug fitment: 14mm x 3/4 reach, gasket seat ** Use Edelbrock head gasket sets. May be used on 348 engines with valve lifts up to . 550 only. Bare heads will have valve guides and seats installed, but will require final sizing and a valve job to match the valves you will be using. Recommended spark plugs are Champion RC12YC or equivalent 14mm x 3/4 reach with flat gasket seat. These heads will only fit 1958-65 348 c. i. d. W engines if an Edelbrock #5409, #7159 or stock large port 409 c. i. d. manifold is used. Proper cylinder wall notching must be checked to ensure exhaust valve to cylinder clearance. Deck thickness: 9/16, rocker stud diameter: 7/16, pushrod diameter: 3/8 (width of slot in guide plate).