Dart Marine Cast Iron 496, 8.1L Big Block Chevy Cylinder Heads, 320cc, 2.190" x 1.800" w/Valves
Bare Heads only with Valves, sold in pairs.
Material: Superior cast iron alloy Comb Chambers: 107cc Intake Valve Dia: 2.190” or 2.250” option Intake Port volume: 320cc Intake Port Dim: Factory 8.1L GM Int Port Location: Factory 8.1L GM Location Intake Gasket: Factory GM 8.1L Gasket or Felpro # QMS96057 Exh Valve Dia.: 1.880” Exh Port volume: 128cc Exhaust Port Dim: 1.530”T x 1.800”W Exh Port Location: Raised .050” from factory location Exhaust Gasket: Factory GM 8.1L Gasket or Felpro # QMS95840 Flow, Intake: 341cfm @ .600” lift Flow, Exhaust: 252cfm @ .600” lift Flow Wet: N/A Freeze Plugs: Dart PN# 32860000B 1 3/8 dia. Brass Head Bolts: Factory GM head bolts + .270 Dowel Holes Head Studs: N/A Manifold: Factory GM or Dart Milling: Min. 100cc .005” = 1cc flat mill only Push Rod length: Must be measured / Factory GM 8.1L Push rod Guide Plate: Dart Adjustable PN# 27001230-4 Retainers: 1.250” or 1.550” Spark Plug: .750” Reach tapered seat Spring Pockets: Inner step 1.265” outer step1.550” Springs: 1.250” Dia. w/ Rotator & 1.550 Valve Length: Intake: 5.235” OAL Exh: 5.425” OAL Valve Stem Dia: 11/32” Valve Train: Factory GM valve train Valve Guides: Integral guides Valve Guide length: N/A Valve Guide clearance: .3435” I.D (.002” w/ .3415 dia valve stem) Valve Guide Spacing: Factory GM 8.1L Valve Seats: Integral intake seat & Hardened ex. seat. Valve Seat dia. 2.450” Int. & 2.000” Exh. Valve Seat angles: 45° Torque: Use factory GM torque procedures, Intake Manifold (M6 x 1) = 106 in lbs Rocker studs (M10 x 1.5) = 37 ft lbs, Valve Cover (M6 x 1) = 106 in lbs Weight: 150 lbs pr.
