JEGS Performance 5.3L engine was designed to be a performance upgrade for 1999-2007 LM7 truck applications or LS swap vehicles. This engine has a noticeable idle and provides large power gains in the mid to upper RPM range. For optimal performance intake and headers recommended. An ECU tune and upgraded injectors are required.

• Horsepower: 460 HP
• Torque: 425 ft.-lbs

Block Information:

• OE LM7/5.3L cast iron
• Bore/Stroke: 3.800 in. x 3.622 in.
• Displacement: 5.3L

Rotating Assembly:

• Crankshaft: OE GM 24-tooth reluctor wheel
• Rods: Stock GM
• Compression Ratio: 10.0:1
• Pistons: Hypereutectic
• Rings: Moly
• Internally balanced

Camshaft Specs:

• Camshaft: Hydraulic roller tappet 
• Cam Duration @ .050 in.: Intake 222 / Exhaust 231
• Cam Lift: Intake .545 in. / Exhaust .545 in.
• Lobe Separation Angle: 112

Cylinder Head Information:

• Cylinder Heads: OE aluminum (Either 799 or 243 castings)
• Combustion Chamber: 64 cc
• Valve Size: 2.000 in. Intake / 1.550 in. Exhaust
• Rocker Arms: Powdered metal roller rockers 1.7 ratio with C-clip upgrade retainer

 Long Block Engine Includes:

• Short Block
• Camshaft
• Timing Set
• Cylinder Heads
• Oil Pump with stock Chevy truck oil pump tube

Note: Oil Pan, Valve Covers, and Timing Cover NOT Included

Recommended Components

• Balancer: Stock Internal Balance
• Flexplate/Flywheel: Stock Internal Balance
• Exhaust: Headers with 1 5/8 in. or 1 3/4 in. Primary Tubes
• Firing Order: Stock
• Fuel: 91-93 Octane
• Fuel Injectors: 35 lbs.-hr at 58 psi
• Oil: 5W30
• Spark Plugs: Stock
• Spark Plug Gap: .035 in.
• Recommended Stall Converter: 2500
• Timing: Set to factory specifications via PCM module (Tune Required)

 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 or break-in oil or conventional (non-synthetic) 10w30 oil with zinc additive for the first 500 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. It is best to avoid long periods of idling during this period. Check the engine oil and coolant levels daily. 

Engines with flat tappet hydraulic cams only - Run the engine between 2,000 and 2,500 RPM's, with no-load on the engine for the first 30 minutes. Let the engine cool down completely and repeat the process 2-3 more times. Do not idle the engine for an extended period at this time, this is critical to break in the camshaft.

At 500 Miles change the engine oil and filter using conventional (non-synthetic) oil with a zinc additive. Check fuel and ignition settings, adjust valves (where applicable).  Drive the next 500 miles normally, without high RPM's (below 5000 RPM), hard use, or extended periods of high loading or long periods of idling.

Change the oil and oil filter again at 1,000 miles. Continue using conventional (non-synthetic) oils and zinc additive, until about 4,000 miles. At that point, you may run a quality 10w30 synthetic oil if you choose. The use of oil with high zinc or a zinc additive for the life of your engine is recommended. 

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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