ATK Core Return Process
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NOTE: Core return can be any Chevy LS 6.0L engine

Engine Specifications

This is an LQ4/408ci stroker based engine with LS3 aluminum heads making a power house with 600hp. Expect great top end power, power brakes may not work due to minimal vacuum. 

• Horsepower: 600 hp
• Torque: 550 lb/ft

Block Information:

• OE LQ4/6.0L iron
• Bore/Stroke: 4.030" x 4.000"
• Displacement: 408ci

Rotating Assembly:

• Crankshaft: Manley 4340 forged 24 tooth reluctor wheel
• Rods: Manley 4340 forged H beam with ARP 8740 bolts
• Compression Ratio: 10.3:1
• Pistons: Manley 2618 forged
• Rings: Moly

Camshaft Specs:

• Camshaft: Hydraulic roller
• Cam Duration @ .050": Intake 240 / Exhaust 256
• Cam Lift: Intake .625" / Exhaust .625"
• Lobe Separation Angle: 113lsa
• Lifters: GM LS7
• Timing Chain: Billet HD .250" roller

Cylinder Head Information:

• Cylinder Heads: GM LS3 aluminum rectangle port
• Combustion Chamber Size: 68.4cc
• Intake Runner Size: 260cc
• Valve Size: 2.165" Intake / 1.590" Exhaust
• Rocker Arms: OE 1.7 ratio with bushing upgrade

Engine Info

• Exhaust: 1-3/4" Headers
• Firing Order: 18726543
• Octane: 91+
• Oil: 10W40
• Oil Filter: Wix or K&N
• Spark Plug Gap: .040"
• Stall Converter: 3000+

Recommended Components

• Balancer: Stock internal balance/per application
• Carburetor: Quick Fuel 850cfm mechanical secondary's #793-Q-850
• Intake Manifold: Edelbrock Victor Jr. #350-28457
• Flexplate/Flywheel: Stock internal balance
• Fuel Pump: Electric 
• Oil Pump: Melling standard volume, high pressure
• Spark Plugs: Autolite #417-104
• Spark Plug Wires: MSD #121-5574
• Timing Control: MSD #121-6014 with baseline of 10deg @0rpm, 20deg @ 500 rpm, 26deg @ 1500rpm, and 31deg at 2500-6500rpm
• Water Pump: Per application

Notes: A PCV valve must be ran; follow valve cover instructions provided. You must run an air-oil separator system such as Moroso #710-85487 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 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 (4 corner setup recommended). 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: Power figures can vary based on parts used by the end user. Some modifications to the vehicle may be required using these and or other aftermarket parts.

Engine Break-In Procedure

Use conventional or break-in oil (non-synthetic) for the first 600 miles of operation. Do not drive for long periods at any single speed, always vary your speed. Do not tow a trailer or put other heavy loads on the vehicle. Check the engine oil and coolant levels daily. 

At 600 Miles change the engine oil and filter using conventional (non-synthetic) oil. Check fuel and ignition settings; adjust valves (where applicable).

After the first 5,000 of service synthetic engine oil may be used. Follow your vehicle owner’s manual for service intervals.

Emissions Note:

This part is only legal for sale and use on Uncontrolled (Non-Emissions Controlled) Vehicles or on vehicles used solely for the purposes of closed competition racing.

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