Product Summary

396, 402, 427, 454, Assembled Cylinder Head Style

  • This powerful, out-of-the-box cylinder head is design matched with an outstanding, unbeatable casting technology
  • Heads have a thick deck design and high capacity water jackets that makes them a reliable choice for street or strip applications
  • Will accept stock pistons and features raised valve cover rails to reduce the chance of valve cover gasket leaks
  • Exhaust port location is raised .500"
  • Features 320cc intake runners and 128cc exhaust runners

Key Specs

Cylinder Head StyleAssembled
Material TypeAluminum
Combustion Chamber Volume133cc
Intake Runner Volume320cc

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Flo-Tek 305-600 Details

Flo-Tek Recommended Setup:

  • Header – Based on Chassis - 2-1/8”
  • Rocker Arms – Isky Roller Rockers 204-96 1.75:1 or Equivalent
  • Intake Manifold – Victor JR or Super Victor

A powerful, out-of-the-box cylinder head design matched with an outstanding, unbeatable casting technology. FLOTEK Aluminum Cylinder Heads are a great choice for out of the box horsepower. These FLOTEK Cylinder Heads offer a thick Deck Design and High Capacity water jackets that makes them a reliable choice for street or strip applications.

The FLOTEK BBC 320 takes stock pistons and has raised valve cover rails. The BBC 320 Exhaust Port location is raised .500".

Valve Springs:

PSK-236-1-7 Up to .600" Lift CL #147 @ 1.90 OP #365 @ 1.22 C/BIND 1.12 O.D 1.53” Single W/D I.D. 1.12


  • 2.250 + .250 Intake Valves
  • 1.880 Stock Length Exhaust Valves
  • 320cc Intake Runners
  • 128cc Exhaust Runners
  • 133cc Combustion Chambers
  • Viton Positive Seals
  • Hardened Chrome Moly Retainers
  • Manganese Bronze Intake & Exhaust Guides
  • Rocker Studs & Guide Plates included - must be torqued during the installation process, must have clearance for valve spring retainers
  • Sold individually
  • Head Bolts: ARP-135-3703 (12pt) & ARP-135-3606 (6pt)
  • Head Studs: ARP-235-4303
  • Head Gasket: Fel-Pro 1017-1 (4.500) & Fel-Pro 1057 (4.630)
  • Stud Girdle: Harland Sharpe G1114 (7/16)
  • Intake Gasket: Fel-Pro 1252-3 (320) & Fel-Pro 1211 (360)
  • Exhaust Gasket: Fel-Pro 1410
  • Spark Plug: 14mm .750 reach, Recommended starting point Accel # 416
  • Head Bolt Torque Specs: 75 ft/lbs w/ oil. Coat head bolts and rocker studs with thread sealant.
  • Rocker Arm Stud Torque: 50 ft-lbs w/ oil
  • Guide Plate: Dart 2700123-4/PC-4247

CARB Warning

For race/ off road use or for use on pre-1966 vehicles.

Emissions warning: this part only legal for sale or use in California for racing (competition) vehicles which may never be used, registered, or licensed for use upon a public highway, or if installed in vehicles model-year 1965 or older; motorcycles model-year 1977 or older; or off-highway recreational vehicles (such as off-road motorcycles and all-terrain vehicles) model-year 1996 and older. Any other use renders the vehicle tampered and not legal for use on California public highways (any public street or roadway, public dirt road, public park, or publicly maintained right of way open to the use of the public for vehicular travel). Violations subject to $37,500 penalty per violation per vehicle, revocation of registration, loss of use on California public right of ways, and proof of correction for tampering. There are similar restrictions and penalties under federal law and the laws of all other states with penalties under federal law of up to approximately $45,268 per tampered vehicle and/or engine.

Flo-Tek 305-600 Specifications

MFG. Part #305-600
Cylinder Head StyleAssembled
Material TypeAluminum
Combustion Chamber Volume133cc
Intake Runner Volume320cc
Exhaust Runner Volume128cc
Combustion Chamber Volume Range130cc - 139cc
Intake Runner Volume Range320cc - 329cc
Exhaust Runner Volume Range120cc - 129cc
CNC-Machined RunnersNo
Spark Plug StyleAngle
Intake Port ShapeRectangle
Exhaust Port ShapeD-port
Intake Valve Diameter2.25"
Intake Valves IncludedYes
Exhaust Valve Diameter1.88"
Exhaust Valves IncludedYes
Valve Spring IncludedYes
Valve Seat MaterialPowdered Metal
Valve Stem Seals IncludedYes
Valve Stem Seal TypePositive Stop
Valve Stem Seal MaterialViton
Valve Guides IncludedYes
Valve Guide MaterialManganese Bronze
Locks IncludedYes
Lock Style7 Degree and 10 Degree
Retainers IncludedYes
Retainer MaterialChromoly Steel
Guideplates IncludedYes
Rocker Arms IncludedNo
Sold in QuantityEach
GTIN Code850134007686