ATK Core Return Process
JEGS and ATK appreciate your business and want to ensure that your core return is as smooth as possible.

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NOTE:

• Core return can be any Jeep 242ci/4.0L engine

Engine Info

• Exhaust: Headers/Performance exhaust
• Firing Order: 153624
• Octane: 91+
• Oil: 10W30 (Conventional / Non Synthetic) with zinc additive for first 3000 miles
• Oil Filter: Wix or K&N
• Spark Plug Gap: .035"
• Stall Converter: Stock
• Timing: Factory settings

Recommended Components

• Balancer: OE
• Intake Manifold: OE
• Flexplate/Flywheel: OE
• Fuel Pump: OE
• Spark Plugs: Autolite #417-AP985
• Spark Plug Wires: OE
• Water Pump: OE Per application

Notes: This engine will work with all stock components, ATK recommends a cold air intake, headers, exhaust, and a chip for maximum power potential.

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 process 2-3 more times. Do not idle the engine for any 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. Use of oil with zinc or a zinc additive for the life of your engine is recommended. 

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