Recommended for engines with 4.000” bore or larger. Maximum competition, competition modified drag racing, circle track. Over 7,000 RPM.
Dart’s PRO1 15° 250cc LS CNC ported Aluminum cathedral port cylinder heads for GM LS series small block V8 engines take performance to the next level.
This LS CNC cathedral port head is machined on a dedicated casting with extra thick sections to maintain the proper wall thickness after porting. Due to the large diameter intake valves, the Dart LS CNC head is recommended for use on engines with 4.000 inch and larger cylinder bores. Precise computer controlled CNC machining, multi-angle intake seats, and radiused exhaust seats enhance airflow. Extra material above the ports accommodates valve train upgrades.
Heads are sold individually.
Part Number: 11071040 - 11071143
Comb Chambers: 68cc (6.0 liter)
Intake Valve Dia: 2.08
Intake Port volume: 250cc
Intake Port Dim: 1.065 wide x 3.245 tall
Intake Port Location: stock
Intake Gasket: OE or Fel Pro
Exh Valve Dia.: 1.600
Exh Port volume: 94cc
Exhaust Port Dim: 1.710 wide x 1.430 tall
Exh Port Location: stock
Exhaust Gasket: OE or Fel Pro 1438
Flow, Intake: 322cfm @ .600 lift
Flow, Exhaust: 240cfm @ .600 lift
Manifold: Any aftermarket LS
manifold Milling: .005=1cc
Push Rod length: standard
Push rod Guide Plate: N/A
Retainers: Titanium
Spark Plug: Autolite AR3935
Spring Locators: 1.300 O.D.
Spring Pockets: 1.350 diameter
Springs: 1.290 Beehive 120@1.800 1.295 Dual 140@1.800
Valve Length: Standard
Valve Stem Dia: 8mm
Valve Train: OE (modification required, trim off tabs on stock rocker bar)
or any aftermarket system
Valve Guides: .439” O.D.
Valve Guide length: 2.100”
Valve Guide clearance: .0015”-.002”
Valve Guide Spacing: Standard
Valve Seats: Powder metal
Valve Seat dim: Intake 2.160 O.D. .350 deep Exhaust 1.650 O.D. .350 deep
Valve Seat angles: Intake 32°-45°-60°-70°-80° Exhaust 37°-45°-radius
Stud Girdle: N/A
Torque: OE specs.
Weight: 23lbs. Bare 26lbs. Assembled
Block Use: LS style
