Dart Machinery CNC Ported Pro-1 Chev SB Heads CNC ported heads are no longer just for the pros. Every intake port, every exhaust runner, every valve bowl, and every combustion chamber is 100% CNC machined on special dedicated PRO1 castings. Flows 309 cfm (at .700" lift) intake and 226 cfm exhaust. Assemblies include 2.080"/1.600" valves, 1.550" roller springs, 10 deg. titanium retainers with machined locks, studs, and guide plates. Note: chambers are designed for 4.125" bore or larger.
Part Type: Cylinder Head Application: Chevrolet Small Block Cylinder Head Material: Aluminum Bare or Assembled: Assembled Combustion Chamber Size: 66cc CNC Machined Combustion Chambers: No Intake Valve Angle: 23 Exhaust Valve Angle: 23 Intake Port Volume: 227cc CNC Machined Intake Port: No Intake Port Flow: 309 cfm @ .700" Lift / 28" Intake Port Location: Standard Intake Port Shape: Rectangular Intake Port Dimensions: 2.200" x 1.310" Suggested Intake Gaskets: Fel-Pro 1206 or Equivalent Exhaust Port Volume: 85cc CNC Machined Exhaust Port: No Exhaust Port Flow: 226 cfm @ .700" Lift/ 28" Exhaust Port Location: Standard Exhaust Port Shape: Square Exhaust Port Dimensions: 1.410" x 1.585" Suggested Exhaust Gaskets: Fel-Pro 1404 or Equivalent Spark Plug Style: Angled Suggested Spark Plug: .750” reach, 14mm hex Valve Guides: Yes Valve Guide Spacing: 1.890" exhaust moved .030" from intake Valve Stem Diameter: 11/32" (.3415") Valve Seats: Yes Valve Job: Multi-Angle Intake Valve Diameter: 2.080" Intake Valve Included: Yes Exhaust Valve Diameter: 1.600" Exhaust Valve Included: Yes Suggested Valve Length: 4.965" Valve Spring Pockets: 1.550" (Can cut .030" deeper MAX.) Valve Springs Included: Yes, 1.550" Dual Valve Spring Application: Mechanical Roller, 230lbs. Seat, 550lbs. Open, .750" Max Lift Valve Springs Retainers Included: Yes Valve Locks Included: Yes (10 Degree) Valve Seals Included: Yes Rocker Studs Included: Yes (7/16") Guide Plates Included: Yes Valve Cover Mounting Style: Center Bolt and Perimeter Steam Holes Drilled: No Heat Crossover: No Suggested Head Bolts: ARP 134-3601 or Equivalent Suggested Head Studs: ARP 134-4001 or Equivalent Suggested Stud Girdle: Power Products 43101K, Howards Cams 90101, Jomar 1104 Head Bolt Torque with Oil: 70 ft./lbs. Rocker Stud Torque with Oil: 45 ft./lbs. Intake Bolt Torque with Oil: 35 ft./lbs. Manufacturer: Dart Machinery Manufacturer's Part Number: 11971143P Weight: Warranty: Race Application, No warranty expressed or implied Quantity: Sold as Each
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