Dart big block heads give you the performance advantages of a "rolled over" design. We rotated the intake and exhaust valves two degrees from stock angles- enough to make a dramatic difference in performance while still allowing the use of standard components.
We offer five different intake runners in big block heads: 265cc oval ports and 308cc, 320cc, 360cc, and 410cc rectangular ports. Whether you're building a high torque street engine or a 600ci nitrous motor, Dart has the right head for your big block!
Heart-shaped 119cc combustion chambers. Interlocking ductile iron valve seats are compatible with stainless steel and titanium valves. Exhaust ports raised .300" to improve airflow over short-side radius; raised ports fit most standard headers. Raised head bolt bosses eliminate exhaust flow restriction found in stock heads (require 1" longer head bolts included with Dart head bolt and head stud kits). Spark Plug holes are machined for gasketed 3/4" reach, 5/8" hex plugs. Material: High-density 355 T-6 aluminum. Valve Angle: Intake-24° (rolled 2 degrees) / Exhaust-15° (rolled 2 degrees). Intake Ports: 265cc, 308cc, 320cc, 360cc. Combustion Chambers: 119cc, 139cc as cast; can be milled to 105cc minimum. Intake Valves: 2.250", 2.300", 2.325"+.250" long. Exhaust Valves: 1.880", 1.900", std. length. Guide Spacing: Exhaust moved .045" from bore centerline to accommodate larger valves. Rocker Stud Location: Relocated for revised valve angles; longer exhaust stud required (must use stud girdle designed for Dart heads). Spark Plugs: Gasketed 3/4" reach plugs. Valve Springs: 1.550", 1.625"