ATK GM LM7 347CI 500HP Base LM7-LB-2 Engine

Item #22659

Made in the USA
ATK GM LM7 347CI 500HP Base LM7-LB-2 Engine
ATK LM7-LB-2 GM LM7 347CI Base Engine 500HP
* ** THIS ITEM IS TEMPORARILY OUT OF STOCK *** FREE SHIPPING on ATK Engines. This item ships directly from the manufacturer and is not available for store pickup. Some engines are made-to-order or can be backordered. Delivery can be delayed up to 5 to 6 weeks but typically ship within 2 weeks.
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The ATK LM7-LB-2 GM LM7 347CI Engine 500HP Base is designed to rock the streets and the strips. Producing over 500 horsepower with more than 450 torque, you will feel like riding a beast down the road. This crate engine is ideal for people who already have their own components.

Engine Specifications:

  • Horsepower: 500+
  • Torque: 450+
  • Block: LM7 5.3L Gen 3
  • Bore/Stroke: 3.903 x 3.622
  • Year Range: 1999-2007
  • Displacement: 347CI
  • Crankshaft: OE GM reground 24 tooth reluctor wheel
  • Connecting Rods: Scat 6.125" Forged I Beams with ARP 8740 Bolts
  • Pistons: Wiseco 2618 Forged
  • Piston Rings: Wiseco GFX (Steel top ring)
  • Compression Ratio: 10.3:1 Compression
  • Camshaft: Hydraulic Roller
  • Camshaft Specifications: 228/234 @50 .604/.609 112LSA
  • Camshaft Bearings: Installed & Clocked to OEM Position
  • Cylinder Heads: CNC Ported Cathedral Port cores 2.02/1.60, dual valve springs, titanium retainers
  • Rocker Arms: OE Rocker Arms with trunion upgrade
  • Oil Galley Plugs: Installed & Sealed
  • Weight: 412

ATK specializes in muscle. With the highest quality internal parts and Dyno Proven combinations of every engine built, ATK is able to add the most bang for your buck and back it up with an industry leading warranty.

Don't forget the engine paint!
Engine Paint


ATK High Performance GM LM7/LS1 347CI 500 HP Stage 1 Long Block Crate Engines


Engine Information:

• Oil: 5W30
• Oil Filter: Wix or K&N Recommended Per Your Application
• Fuel Delivery: OE EFI System With Tune or Carb
• Intake Manifold: Factory or Aftermarket
• Fuel Injectors: 36lb for optimal Performance
• Spark Plugs: NGK #3186
• Spark Plug Gap: .035"
• Harmonic Balancer/Damper: Stock Factory Balancer Internally Balanced
• Flex Plate / Flywheel: Stock Internally Balanced
• Tuning: Needs Tune/Preferably Chassis Dyno Tune
• Timing: Set To Factory Specifications Via PCM Module (Tune Required)
• Water Pump: Per Application
• Firing Order: 1 8 7 2 6 5 4 3
• Exhaust: 1 7/8 Headers
• Fuel Pump: Upgraded
• Fuel: 91+ Octane
• Ignition: Coil Packs
• Automatic Transmission Stall Converter: 2500+


Recommended Components:

• Balancer: Stock internal balance/per application
• Intake Manifold: Stock EFI, aftermarket EFI, or carbureted intake
• Flexplate/Flywheel: Stock internal balance
• Fuel Pump: Electric per application
• Fuel Injectors: 36lb injectors
• Spark Plugs: NGK #739-TR5GP
• Spark Plug Wires: Factory
• Water Pump: Per application

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 for their application. Some modifications to the vehicle may be required using these and or other aftermarket parts.

Shipping Instructions

Shipping is free and lift gate will be provided.

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