ATK Engines 5658 Small Block Chevy 355ci/300HP Crate Engine

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

Please CLICK HERE for ATK Core Return Process

NOTE:

• Core return can be any 1967-2000 Small Block Chevy 350ci engine, except 1992-1997 LT1 style engines

Engine Specifications

Power Ratings:

• Factory Specs
  • Horsepower: 300 
  • Torque: 360 lb/ft

Block Information:

• 1987-1995 seasoned OE block
• 2-bolt main
• 1-piece rear main seal
• Passenger side dipstick 
• Displacement: 355 cubic inch

Rotating Assembly:

• Crankshaft: OE reground cast 1-piece seal 
• Balance: External rear (requires 1987-Up style flexplate or flywheel), internal front
• Rods: OE reman powder metal 5.700 in.
• Compression Ratio: 8.5:1
• Pistons: Cast
• Rings: Moly

Camshaft Specs:

• Camshaft: Hydraulic flat tappet 
• Cam Duration @ .050": Intake 224 / Exhaust 224
• Cam Lift: Intake .466" / Exhaust .466"
• Lobe Separation Angle: 114
• Timing Chain: Single roller

Cylinder Head Information:

• Cylinder Heads: Pre-1986 cast iron
• Combustion Chamber: 76cc
• Valve Size: 1.94" Intake / 1.50" Exhaust
• Rocker Arms: Stamped steel 1.5

Oil Pan Information:

• Oil Pan: Black 4 quart
• Oil Pump: Melling standard volume

  Long Block Includes

• Short Block
• Camshaft
• Timing Set
• Cylinder Heads
• Valve Covers
• Timing Cover
• Oil Pan
• Oil Pump & Pickup Tube

Notes: If replacing a pre-1987 (2-piece rear main seal) engine, a new external balance flexplate/flywheel for 1987-Up style engines will be required. This engine will also require a passenger side dipstick (1980-Up vehicles). Driver's side dipstick will not work (Pre-1979).  This engine has provisions for a mechanical fuel pump. Will require stock style spin-on oil filter adapter 555-23605 or equivalent.

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.