Engine and Performance Recommendations for this cylinder head: Maximum performance, Full Competition, unlimited Oval and Super Classes over 7000 rpm, 400+ c. i. The result of three decades of cylinder head development, Iron Eagle heads incorporate features that were previously available only in expensive aluminum cylinder heads. We designed Iron Eagle heads for street performance, bracket racing, oval track competition, and high-performance marine use. We offer five different intake ports165cc, 180cc, 200cc, 215cc, and 230cc that cover virtually every engine application. Dart Iron Eagle heads have standard features you don't get in other factory and aftermarket cast-iron cylinder heads. Long-wearing bronze valve guides (except S/S), multi-angle intake valve seats, and hardened and radiused exhaust seats are standardPit Stop USA offers Dart Iron Eagle Platinum Cylinder Head - Bare - 64cc Chamber - 230cc Intake Runner - SB Chevy 327, 350, 400 - Straight Plug - 2.08", 1.60" Valves 10720040P at low everyday prices. Be sure to check out all of our products from Dart Machinery including Dart Cast Iron Cylinder Heads - Small Block Chevy.