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Product Summary

Long Block Crate Engine Type, 9.9:1 Compression Ratio

  • Block: Seasoned 6.0L Iron Gen IV
  • Bore/Stroke: 4.030” x 4.000”
  • Displacement (cu.in): 408
  • Crankshaft: Manley 4340 forged 24 tooth reluctor wheel
  • Rods: Manley 4340 forged H beam 6.125” ARP 8740 bolts
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Key Specs

Crate Engine TypeLong Block
Engine Displacement7.4 liters
Compression Ratio9.9:1
Camshaft TypeHydraulic Roller
Cylinder Head MaterialAluminum
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Need To Know

Truck Shipment

Truck shipments must be pre-paid with a credit card, certified check or money order

Quick and Easy Returns

Return Policy

ATK Engines HP451PC Details

Engine Specifications:

  • HP: 525
  • TQ: 550
  • Block: OE block 1991-1995 Gen V 4 bolt main 1pc seal (NO MECHANICAL FUEL PUMP PROVISION)
  • Bore/Stroke: up to 4.310” x 4.000”
  • Displacement: 454
  • Crankshaft: OE Reground external balance
  • Rods: OE powder metal 6.135”
  • Pistons: Forged 9.9:1 compression
  • Rings: Moly
  • Camshaft: Hyd. roller
  • Cam Specs: 225/235 @50 .595in/.601ex 112LSA
  • Timing Chain: Double roller
  • Cylinder Heads: Edelbrock aluminum E-street 110cc/290cc 2.19/1.88
  • Rocker Arms: Billet aluminum 1.7 ratio
  • Oil Pan: Rear sump
  • Oil Pump: Melling high volume
  • Balancer: PowerBond external balance 8” #PB1451-N
  • Flexplate/Flywheel: Pioneer #FRA-321 external balance 168 tooth
  • Intake Manifold: Edelbrock performer RPM dual plane #7161
  • Distributor: HEI (Iron gear)
  • Water Pump: OE long pump
  • Carburetor: Quick Fuel 780CFM vacuum secondary’s with electric choke #HR-780
  • Fuel Pump: No mechanical fuel pump provision, must run an electric pump
  • Spark Plugs: Autolite #3923
  • Spark Plug Wires: 8mm

    Engine Info:

  • Oil: Conventional / Non Synthetic 10W30 with Comp Cam zinc additive #159 for first 3000 miles
  • Oil Filter: Wix or K and N per application
  • Timing: 34-36 Degrees
  • Spark Plug Gap: .035”
  • Firing Order: 18436572
  • Octane: 91+
  • Stall Converter: 2200-2500
  • Exhaust: 1 5/8 Headers

    Disclaimer: The parts listed are ATK’s recommendations of parts to be used to obtain our power figures listed. Power figures can vary based on parts used by the end user. It is the customer’s responsibility to verify components will work in their application. Some modifications to the vehicle may be required using these and or other aftermarket parts. . ATK reserves the right to substitute parts used in engines if necessary.

  • CARB Warning

    Follow EPA, CARB, and state regulations for engine changes

    Emissions warning: this part is for vehicle engine changes, not direct oem engine replacements. In California, engine changes are legal when done in compliance with California bureau of automotive repairs (bar) engine change policy. For assistance, call bar referee at: (800) 622-7733. And see https://bar.Ca.Gov/consumer/smog_check_program/engine_changes. All customers must comply with federal epa mobile source enforcement memorandum no. 1a (and addendum) and all applicable state regulations when conducting engine changes. Improper installation and/or use of this part in California may subject the installer and/or owner to a $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 laws of all states for use of this engine change part on makes or models of vehicles that render them noncompliant with applicable state and/or federal emission laws with penalties under federal law of up to approximately $45,268 per tampered vehicle and/or engine

    ATK Engines HP451PC Specifications

    KEY SPECS
    MFG. Part #HP451PC
    BrandATK Engines
    Crate Engine TypeLong Block
    Engine Displacement7.4 liters
    Compression Ratio9.9:1
    Camshaft TypeHydraulic Roller
    Cylinder Head MaterialAluminum
    Carburetor IncludedYes
    Intake Manifold IncludedYes
    Distributor IncludedYes
    Valve Covers IncludedYes
    Engine BalanceExternal
    Cylinder Heads IncludedYes
    Rear Main Seal Style1-piece
    Throttle Body IncludedNo
    Oil Pan IncludedYes
    Timing Cover IncludedYes
    Water Pump IncludedYes
    Harmonic Balancer IncludedYes
    Flexplate IncludedYes
    Flywheel IncludedNo
    Air Cleaner IncludedNo
    Spark Plugs IncludedYes
    Spark Plug Wires IncludedYes
    Computer IncludedNo
    Wiring Harness IncludedNo
    GENERAL
    AssembledYes
    Material TypeCast Iron
    Sold in QuantityEach
    Crate Engine FamilyChevy Big Block
    Supercharger IncludedNo

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