Product Summary

Long Block Crate Engine Type, 10.3:1 Compression Ratio

  • Oil: Conventional / Non Synthetic 10W30
  • Oil Filter: Wix or K&N per application
  • Timing: 34-36 Degrees
  • Spark Plug Gap: .035”
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Key Specs

Crate Engine TypeLong Block
Compression Ratio10.3:1
Engine Displacement347 cu. in.
Camshaft TypeHydraulic Roller
Cylinder Head MaterialAluminum
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Need To Know

Made to Order

This custom item will ship when completed

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ATK Engines LM7-LB-2 Details

This is an LM7 (Iron LS1/LS6) based engine with CNC Ported Cathedral Port Aluminum heads making a very streetable 500HP+. Expect big mid to upper end power, will have a noticeable idle. For optimal Performance you will need headers, chassis dyno tune and 36lb injectors. Your engine may not necessarily come with all components listed, but they are listed as our recommendations of parts to run for optimal performance.

Engine Specifications:

  • HP: 500
  • TQ: 450
  • Block: OE LM7 5.3L Gen III
  • Bore/Stroke: 3.903” x 3.622”
  • Displacement (cu.in): 347
  • Crankshaft: OEM GM 24 tooth reluctor wheel
  • Rods: Scat 4340 forged I beam 6.125” with ARP 8740 bolts
  • Pistons: Wiseco forged 10.3:1 compression
  • Rings: Moly
  • Camshaft: Hyd. Roller
  • Cam Specs: 228/234 @50 .604/.609 112LSA
  • Timing Chain: Billet HD .250” roller
  • Cylinder Heads: CNC ported cathedral port cores 2.02/1.60 valves, dual springs, titanium retainers
  • Rocker Arms: OE 1.7 ratio
  • Oil Pump: Melling
  • Recommended Components:

  • Flexplate/Flywheel: Stock internally balanced
  • Balancer: Stock internally balanced/per application
  • Intake Manifold: Stock/Aftermarket EFI intake or Carbureted setup
  • Water Pump: Per application
  • Fuel Pump: Electric per application
  • Fuel Injectors: 36lb injectors
  • Spark Plugs: NGK #3186
  • Spark Plug Wires: Factory
  • Engine Info:

  • Oil: Conventional / Non Synthetic 10W30
  • Oil Filter: Wix or K and N
  • Timing: Set to factory specifications via PCM module (ECM TUNING REQUIRED).
  • Spark Plug Gap: .040”
  • Firing Order: 18726543
  • Octane: 91+
  • Stall Converter: 2200-2500
  • Exhaust: 1 5/8 + Headers
  • Notes: This engine can replace the 1999-2007 Chevy 5.3L LM7 engine with supporting modifications or any other factory LS equipped vehicle. It can also be retrofitted for aftermarket EFI/Carb setups. ECM MUST BE TUNED, not doing so can damage the engine. : A PCV valve must be ran; please follow the valve cover instructions provided. You must also run an Air-Oil separator system such as the Moroso #85487 to capture the excess crankcase vapors LS engines are known for. If you are not running a MAP Sensor, the MAP timing option in the timing control box must be zeroed out all the way across. Failure to do so will allow the controller to add timing which can lead to detonation. You must also run some sort of a steam line kit that dumps to your water pump, radiator or radiator hose; we recommend a 4 corner setup like the Trick Flow #TFS-306SB601. This allows air pockets/hot spots to escape the heads and can also be used to purge out trapped air when filling the radiator for the first time.

    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 LM7-LB-2 Specifications

    KEY SPECS
    MFG. Part #LM7-LB-2
    BrandATK Engines
    Crate Engine TypeLong Block
    Compression Ratio10.3:1
    Engine Displacement347 cu. in.
    Camshaft TypeHydraulic Roller
    Cylinder Head MaterialAluminum
    Piston MaterialForged Aluminum
    Carburetor IncludedNo
    Intake Manifold IncludedNo
    Distributor IncludedNo
    Valve Covers IncludedYes
    Cylinder Heads IncludedYes
    Throttle Body IncludedNo
    Timing Cover IncludedNo
    Oil Pan IncludedNo
    Water Pump IncludedYes
    Harmonic Balancer IncludedNo
    Flexplate IncludedNo
    Flywheel IncludedNo
    Air Cleaner IncludedNo
    Spark Plugs IncludedNo
    Spark Plug Wires IncludedNo
    Computer IncludedNo
    Wiring Harness IncludedNo
    Reluctor Wheel24x
    GENERAL
    Bore x Stroke (in)3.903" x 3.622"
    Material TypeIron
    Sold in QuantityEach

    Questions & Answers

    Fitment

    • GM LM4

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    • GM L59

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    • GM LMG

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    • 4.8 Chevy LS V8

    • GM L59

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    • 4.8 Chevy LS V8

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    • 6.2 Chevy LS V8

    • GM LC9

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    • GM LC9

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    • GM LH6

    • GM LM4

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    • 4.8 Chevy LS V8

    • GM LM7

    • 4.8 Chevy LS V8

    • GM L33

    • GM L94

    • GM LM7

    • 4.8 Chevy LS V8

    • GM L33

    • GM L94

    • 4.8 Chevy LS V8

    • GM LM7

    • 4.8 Chevy LS V8

    • GM L33

    • GM L94

    • 4.8 Chevy LS V8

    • GM LM7

    • 4.8 Chevy LS V8

    • GM L33

    • GM L94

    • GM L20

    • GM LC9

    • GM LMG

    • GM L33

    • GM L59

    • GM LM7

    • GM LM7

    • 4.8 Chevy LS V8

    • GM L20

    • GM LM7

    • GM LY2

    • 4.8 Chevy LS V8

    • GM L20

    • GM L94

    • GM LM7

    • GM LY2

    • GM L94

    • GM LC9

    • GM LMG

    • GM LM7

    • GM L59

    • GM LM7

    • 6.2 Chevy LS V8

    • GM LH8

    • GM LH9

    • GM LH8

    • GM LH9

    • GM LS1

    • GM LS3

    • GM LS1

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