Performer RPM E-Tec cylinder heads feature an LT1-style raised runner intake port design for increased air-flow and ultimate performance. Available in 170cc or 200cc runner size, they both feature high-quality stainless steel intake and exhaust valves, 64cc combustion chambers and high flow intake and exhaust ports. The high-velocity Intake and exhaust runners are hand blended in the bowl area and the intake entries and exhaust exits are CNC profiled for increased air-flow. a unique combustion chamber design positions the spark plug closer to the center of the cylinder, promoting uniform atomization of the air/fuel mixture for more efficient combustion resulting in more power. These heads include adjustable rocker stud and guide plate set-up for use with adjustable rockers or washers to properly position the stud height to accomodate factory style self-aligning rocker arms. The casting is manufactured of virgin A356 aluminum and heat treated to T6 spec for superior quality. An extra-thick 5/8" deck and Heli-coil threaded inserts offer improved durability. RPM E-Tec heads are dual-drilled and for to accept 1987-95 centerbolt and/or 1986 & prior flange mount valve covers. RPM E-Tec cylinder heads are available fully assembled and ready to bolt on or bare for use with your own valve train components. Made in USA. Cylinder Head Specifications: Combustion chamber volume: 64cc Intake runner volume: 170cc Exhaust runner volume: 70cc Intake valve diameter: 1. 94" Exhaust valve diameter: 1. 55" Valve stem diameter: 11/32" Valve guides: Manganese bronze Deck thickness: 5/8" Valve spring diameter: 1. 46" Valve spring maximum lift: 0. 575" Rocker stud: 3/8" Guideplate: Hardened steel Pushrod diameter: 5/16" Valve angle: 23° Exhaust port location: Stock Spark plug fitment: 14mm x 3/4 reach, gasket seat Made In USAPit Stop USA offers Edelbrock Performer RPM E-Tec 170 Cylinder Head - Assembled - SB Chevy - Combustion Chamber Volume: 64cc, Intake Runner Volume: 170cc, Intake Valve: 1.94", Exhaust Valve: 1.55", Standard Port - Valve Angle: 23° - Sold Individually 60979 at low everyday prices. Be sure to check out all of our products from Edelbrock including Edelbrock Aluminum Heads - Small Block Chevy.