• Chevrolet 454 Cylinder Head 320CC GEN IV - CH454A

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Other products by AA MIDWEST
Item #: CH454A
Reg. Price: USD $545.00
Our Price: USD $504.00


More About Chevrolet 454 Cylinder Head 320CC GEN IV - CH454A:


Racers, street enthusiasts, truck owners and boaters looking for an affordable cast iron Big Block Chevy cylinder head that can support over 850 horsepower right out of the box can rejoice as EngineQuest (EQ) has just expanded their product line. EQ’s Big Block Chevy replacement cylinder heads surpass any production unit by producing outstanding horsepower and torque improvements for virtually all Big Block Chevy engines from a mild 454 to a supercharged 572.  


This head offers superior flow characteristics. Its cast, machined and assembled with great features such as multi-angled intake seats and radiused exhaust valve seats, revised water jackets for better thermal conductivity for reduced chance of detonation, thick deck surfaces, hardened exhaust valve seat, manganese intake and bronze exhaust valve guides. This head has a 119cc chamber volume that is “compression friendly” for street or marine applications.


  • Intake runner 320cc, combustion chamber 119cc
  • These heads are  24/15 degree, stock is 26/17
  • Valve head diameter 2.250" / 1.880"
  • Rectangular intake ports
  • Drilled and tapped for accessory bolt holes
  • Proudly made in New Zealand
  • No core charge

Tech note:
When installing the cylinder heads a set of ARP 135-3703 head bolts or equivalent should be used.



Port Volume: 320cc 135cc

Port Dimension: 1.700" X 2.450" 1.560" X 1.900"

Port Location: Stock raised .500"

Valve Angle: 24°(stock angle is 26°) 15° (stock angle is 17°)

Valve Head Diameter: 2.250" 1.880"

Valve Length: 5.468" (std length + .250") 5.468" (std length + .100")

Valve Seat Dimensions: 2.380" X 1.900" X .375" 2.006" X 1.900" X .375"

Valve Seat Angles: 40/45/60/75 40/45/Radius

Valve Guide Diameter: 11/32" 11/32"

Valve Guide Dimensions: .502" O.D. X 2.100"L X .530" boss dia. .502" O.D. X 2.100"L X .530" boss dia.

Valve Guide Material: Premium bronze material for superior heat dissipation and longer life

Material: Cast iron

Chamber Volume: 119cc

Spark Plug Location: Optimized for best performance

Spark Plug Type: 14mm, .750" reach, 5/8" hex, flat gasket style

Spring Pocket Diameter: 1.625"

Pushrod Diameter: 3/8" (larger diameter will require clearancing)

Weight: 78 lbs


• Optimal port design for greater flow, better atomization & enhanced dynamics

• Unique multi-angled intake & radiused exhaust valve seats for increased flow and horsepower output

• Hardened valve seat for exceptional durability even when used in extreme applications with harsh fuels

• More efficient water jacket design for improved cooling and thermal conductivity, and reduced risk of detonation

• Thick deck faces with added material to allow angle milling for increased compression

• Revised combustion chamber design for excellent combustion thermodynamics and enhanced fuel efficiency

• All accessory bolt holes drilled and tapped to exact tolerances

Tech Notes

Flat Milling: .006" per cc

Angle Milling: .0075" per cc (excessive milling can cause intake manifold misalignment)

Head Bolt Torque: Refer to cylinder head bolt manufacturer's specifications

Rocker Stud Torque: 45 lb/ft

Intake Manifold Torque: 35 lb/ft

Spring Pocket Machining: Can be machined to 1.750" maximum diameter, cannot be machined deeper

Pushrod Length: Measuring with length checker required to verify pushrod geometry

Piston to Valve Clearance: Must be verified -minimum clearance is .080" intake and .100" exhaust

Retainer to Guide Clearance: Must always be measured when using high lift cams

Chamber to Dome Clearance: Must always be checked with domed pistons, clearancing may be necessary

Chamber Volume: Varies due to valve margins and dishes, should always be verified before installation

Valve Guide Clearance: Must be checked due to the variance in valve stem diameters between manufacturers

Recommended clearance: intake .0015"-.0016", exhaust .002"-.0025"

Water jackets require flushing prior to cylinder head installation

Cylinder Head Bolts: Raised exhaust ports require longer exhaust side head bolts/studs

Header/Spark Plug Clearance: Spark plug/ wire boot clearance verification is required prior to header installation.

Minor modifications may be necessary in order to achieve proper clearance.




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