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 Small Block Chevy 350ci engine, except 1992-1997 LT1 style engines

Engine Info

• Carburetor: Quick Fuel 680cfm vacuum secondary electric choke #793-HR-680-VS
• Balancer: 8" internal balance
• Distributor: HEI (iron gear)
• Exhaust: 1-5/8" Headers
• Flexplate/Flywheel: External balance 168 tooth 1987-Up
• Intake Manifold: Weiand Stealth dual plane #925-8150
• Firing Order: 18436572
• Fuel Pump: Holley Mechanical 110gph #510-12-327-11 
• Octane: 91+
• Oil: 10W30 (Conventional / Non Synthetic) with zinc additive for first 3000 miles
• Oil Filter: Wix or K&N
• Spark Plug Gap: .035"
• Spark Plugs: Champion #RV12C or NGK #739-YR5
• Spark Plug Wires: 8mm
• Stall Converter: 2200-2500
• Timing: 34-36 Degrees 
• Water Pump: OE long pump

 Disclaimer: The parts listed are ATK's recommendations of parts to be used to obtain the power figures listed. 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. 

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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