Cylinder Head Specifications: Combustion chamber volume: 58cc; Intake runner volume: 225cc; Exhaust runner volume: 62cc; Intake valve diameter: 2.15"; Exhaust valve diameter: 1.60"; Valve stem diameter: 11/32"; Valve guides: Manganese bronze; Deck thickness: 5/8"; Valve spring diameter: 1.55"; Valve spring maximum lift: .650"; Rocker stud: N/A; Guideplate: N/A; Pushrod diameter: 5/16"; Valve angle: 16°; Exhaust port location: Raised; Spark plug fitment: 14mm x 3/4 reach, gasket seat * These cylinder heads are for use on 1967-1991, 318-360 c.i.d. Chrysler LA engines. They feature fully CNC ported 58cc combustion chambers and have an intake port volume of 225cc. These cylinder heads are an in-line valve design incorporating a 16° valve angle (stock is 18°) for improved air flow and increased power levels over heavily ported stock versions. They also feature the Chrysler W5 bolt pattern and have raised exhaust ports. The intake port has also been raised approximately 3/4" and the flange has also been extended to accommodate a stock (race) intake manifold such as our Super Victor #2815. Finally, a 5.56" overall length valve (+0.600" from stock) and raised rocker cover permit larger port cross-sections than in the stock head. Four versions are available; bare, bare with valves, complete (for hydraulic/flat tappet cams and solid roller cams) and Pro Port Raw. End-seal spacers are provided. ** These heads require the use of a 14mm x 3/4" reach, flat gasket spark plug with a heat range appropriate to your application. Deck thickness: 5/8", pushrod diameter: 5/16". *** These heads are designed to accomodate stock Big Block Mopar Wedge Rocker arm assemblies (.150" minimum intake offset).