ATK Chevy 434CI Short Block Forged Flat Top SP48 Engine

Item #22712

Made in the USA
ATK Chevy 434CI Short Block Forged Flat Top SP48 Engine
SP48 ATK Chevy 434CI Short Block Forged Flat Top
* ** 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.
- +
Quantity: close


Boost the performance of your ride to street standards with this ATK SP48 Chevy 434CI Short Block Forged Flat Top. It is designed with high cubic inches to produce more power for hardcore street and race cars. Its rotating assembly is fully forged, balanced and blueprinted for high-powered performance.

Engine Specifications:

  • Block: Dart SHP 4 Bolt Main 2pc Seal D/S Dipstick
  • Bore/Stroke: 4.125 x 4.000
  • Displacement: 427 C.I.D.
  • Crankshaft: Scat 4340 Forged 4.000" Stroke Internally Balanced
  • Connecting Rods: Scat 4340 Forged H Beam 6.000" ARP 8740 Bolts
  • Pistons: Forged +4cc Flat top 2 Valve Reliefs
  • Piston Rings: Moly Rings
  • Compression Ratio: 58cc=12.2:1/64cc=11.4:1
  • Camshaft Bearings: Installed & Clocked to OEM Position
  • Freeze Plugs: Brass Installed & Sealed
  • Oil Galley Plugs: Installed & Sealed
  • Weight: 285

Every great build needs a solid foundation! For that reason, we take the hard work out of the picture by selling short blocks that are ready for you to complete yourself. Our GM Short Blocks are most commonly packaged as the engine block assembled with Pistons, Piston Rings and Crankshaft installed.

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 Chevy 427 Dart Race Series Short Blocks


Engine Information:

• Oil: 10W30
• Harmonic Balancer/Damper: Internally Balanced
• Flex Plate / Flywheel: internally Balanced
• Camshaft: Reduced Base Circle Camshaft


Recommended Components:

• Balancer: Internal balance
• Flexplate/Flywheel: Internal balance (Pre 1985 2-piece rear main engine)
• Head Gasket: .038" thickness or per application
• Oil: 10W30 Non synthetic for first 3000 miles
• Oil Filter: Wix or K&N per application

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