Cylinder Head Specifications: Combustion chamber volume: 60cc; Intake runner volume: 170cc; Exhaust runner volume: 60cc; Intake valve diameter: 1.90" / 2.02"; Exhaust valve diameter: 1.60"; Valve stem diameter: N/A; Valve guides: Manganese bronze; Deck thickness: 5/8"; Valve spring diameter: 1.460"; Valve spring maximum lift: .550"; Rocker stud: 3/8" with guide plate; Guideplate: Hardended steel; Pushrod diameter: 5/16"; Valve angle: N/A; Exhaust port location: Stock; Spark plug fitment: 14mm x 3/4 reach, gasket seat * Use with Hydraulic Flat Tappet camshafts .550" max lift. (NOT compatible with Hydraulic Roller Camshafts) Recommended spark plugs are Champion RC12YC or equivalent 14mm x 3/4" reach with flat gasket seat. Requires hardened pushrods. 289-302 c.i.d. with 7/16" head bolts requires #9680 head bolt bushing kit. 1.90" heads are ideal for stock pistons; 2.02" heads require additional piston to valve clearance. Rocker arm studs & guide plates are not included with bare versions of E-Street cylinder heads.