ATK Chrysler 360 Magnum Engine 320HP Complete HP73C

Item #22621

Made in the USA
ATK Chrysler 360 Magnum Engine 320HP Complete HP73C
HP73C ATK Chrysler 360 Magnum Complete Engine Long Block
* ** THIS ITEM IS TEMPORARILY OUT OF STOCK *** FREE SHIPPING on ATK Engines. This item ships directly from the manufacturer and is not available for store pickup. Some engines are made-to-order or can be backordered. Delivery can be delayed up to 5 to 6 weeks but typically ship within 2 weeks.
Free Shipping on this item


If you are looking for smooth performance and good boost, then the ATK HP73C Chrysler 360 Magnum Engine 290HP Complete is the one to choose. It is designed with well-suited components to perform at its peak without setbacks. 320 horsepower combined with amazing 410 torque makes this crate engine a perfect addition to a street cruiser.

Engine Specifications:

  • Horsepower: 320
  • Torque: 410 lbs./ft.
  • Block: Seasoned OE Magnum
  • Bore/Stroke: 4.040 x 3.580
  • Displacement: 360 C.I.D.
  • Crankshaft: OE Cast 3.580" Externally Balanced
  • Connecting Rods: OE Steel Rod 6.123" Stock Bolts
  • Pistons: Hypereutectic Dished
  • Piston Rings: Moly Rings
  • Compression Ratio: 10.1:1 Compression
  • Camshaft: Hydraulic Roller
  • Camshaft Specifications: Stock Magnum Grind
  • Camshaft Bearings: Installed & Clocked to OEM Position
  • Cylinder Heads: Magnum 65cc 1.78/1.50
  • Freeze Plugs: Brass Installed & Sealed
  • Rocker Arms: Steel 1.6 Pedestal
  • Oil Galley Plugs: Installed & Sealed
  • Oil Pan: OE 5qt.
  • Weight: 430

ATK specializes in muscle. With the highest quality internal parts and Dyno Proven combinations of every engine built, ATK is able to add the most bang for your buck and back it up with an industry leading warranty.

Don't forget the engine paint!
Engine Paint


ATK High Performance Chrysler 360 Magnum 320 HP Stage 3 Long Block Crate Engines


Engine Information:

• Oil: 10W30
• Oil Filter: Wix or K&N Recommended Per Your Application
• Fuel Delivery: Quick Fuel Carburetor 680cfm #HR-680-VS
• Intake Manifold: Edelbrock Performer RPM Air-Gap Dual Plane #7577
• Spark Plugs: Autolite #3923
• Spark Plug Gap: .035"
• Harmonic Balancer/Damper: POWERBOND Externally Balanced #PB1186-N
• Flex Plate / Flywheel: Pioneer Flex Plate #FRA-478 (requires Ext. Balance Converter)
• Timing: 34-36 Degrees Total
• Water Pump: Stock
• Firing Order: 1 8 4 3 6 5 7 2
• Exhuast: 1 5/8 Headers
• Fuel Pump: Holley 110GPH Mechanical Fuel Pump
• Fuel: 87 Octane
• Ignition: MSD Pro Billet #8388
• Automatic Transmission Stall Converter: Stock (If using a Neutral Balance Converter, you need to use a B&M Flex Plate #10242 (externally balanced)

Disclaimer: The parts listed are ATK’s recommendations of parts to be used to obtain our power figures listed. Power figures can vary based on parts used by the end user. It is the customer’s responsibility to verify components will work for their application. Some modifications to the vehicle may be required using these and or other aftermarket parts.

Shipping Instructions

Shipping is free and lift gate will be provided.

Eastwood Offers Free Lifetime Technical Support

Click here for product SDS information

Attention California Residents - Proposition 65

Proposition 65 Warning WARNING - Cancer and Reproductive Harm -


Customer Reviews

Questions & Answers