Bolt-on Edelbrock performance for AMX, Javelin, Jeep and more. Designed for 1967-91 343, 360, 390 and 401 AMC engines. These heads include adjustable rocker stud and guide plate set-up for use with small block Chevy style adjustable 1.6:1 ratio rockers. The intake flange is dual-drilled to accommodate early and late model intake bolt patterns, covering 1967-91. Complete heads include larger-than-stock valve springs to handle most high-lift cams. Features stock location intake ports for compatibility with standard manifolds and headers. A direct bolt-on for 1970 and later engines with 1/2" head bolts, these heads include step-dowel pins for pre-1970 engines. Dual-quench combustion chamber produces approximately 9.5:1 compression in 401 V8s. 45 intake seat angle offers improved mid- to high-lift flow over the stock 30 angle. Performer heads #60129/#60139 have a machined heat crossover for 50-state emissions legal performance. Made in USA. Edelbrock Performer RPM Cylinder Head 60109 Chamber Size 54cc - Bare - Single - w/Exhaust Crossover Port - 67-91 AMC 343/360/390/401Out-of-the-Box Bolt-On PerformanceHand-Blended Intake and Exhaust BowlsCNC-Matched Intake/Exhaust Ports in Std LocationThicker Deck Surfaces than Other Brands54cc Dual-Quench Combustion ChamberOffers Improved Mid To High Lift FlowPit Stop USAoffers Edelbrock Performer RPM Cylinder Head 60109 at low everyday prices. Be sure to check out all of the products from Edelbrock including Edelbrock Engine Parts and Accessories, Edelbrock Cylinder Heads, Edelbrock Aluminum Cylinder Heads - AMC.