ATK HPE427NAATKHEAD Dart LS Next 427CI 700HP+ Long Block



Out of stock|Lead Time: Estimated: 4 - 6 weeks

SKU: HPE427NAATKHEAD Categories: ,


ATK’s new Elite Series LS Long Blocks are a step of above the rest. Every engine is a well thought out parts combination that is purpose built for each application. All of our Elite Series long blocks are fully machined, blueprinted and dyno tested to ensure quality prior to shipping. This engine is built for Naturally Aspirated applications.

Engine Specifications:
• HP: 700+ (Naturally Aspirated)
• TQ: 600+ (Naturally Aspirated)
• Block: Dart SHP LS Next Cast Iron
• Bore/Stroke: 4.125″ x 4.000″
• Displacement ( 427
• Crankshaft: Manley 4.000″ Stroke Internally Balanced 58 Tooth
• Rods: Manley H Beams 4340 Forged 6.125″ ARP 8740 Bolts
• Pistons: SRP 4032 Forged Skirt Coated
• Compression Ratio: 11:1
• Rings: JE Pro Seal with Carbon Steel Top Ring
• Camshaft: Hyd. roller
• Cam Specs: Custom ATK Grind
• Cylinder Heads: ATK LS3 69cc/260cc with Stainless Steel Severe Duty Valves, Titanium Retainers and PAC .700″ lift Springs
• Head Fasteners: ARP Head Bolts
• Head Gaskets: Cometic MLX
• Lifters: Johnson 2116LSR Link Bar
• Rocker Arms: OE powdered metal 1.7 ratio with Trunnion Upgrade
• Oil Pump: Melling 10295 Standard Volume High Pressure

Recommended Components:
• Oil- 20W50
• Oil Filter: Wix
• Fuel System – OE EFI System or Aftermarket
• Intake – Stock Fuel Injected or Aftermarket
• Balancer- SFI Internally Balanced
• Flex plate/Flywheel- Stock Internally Balanced
• Timing- Set to Factory Specifications Via PCM Module (Tune Required)
• Spark Plug: NGK BR7
• Tuning: Chassis dyno tune required
• Firing Order- Stock
• Fuel – 91+ Octane
• Recommended Stall Converter- 2800+ based on application
• Headers- 1 7/8”+ depending on application


  • Dart LS Next SHP Skirted Block – The Dart block features a full skirt design with a priority main oiling system, steel four bolt main caps and is setup to run a 4 or 6 bolt cylinder head.
  • Manley 4340 Forged Crankshaft – Manley Pro Series crankshafts can make your short block bulletproof. They feature forged 4340 construction and undergo a multi-step heat-treatment process and are then nitrided for added strength. The crankshafts are stress-relieved, shot-peened, and magnafluxed. Manley Pro Series crankshafts have micro-polished large .125 in. radius journals, gun-drilled mains, and lightened rod journals for weight reduction. The counterweights are fully profiled and they are designed for internal balancing.
  • Manley H Beam Connecting Rods – When it comes to H-Beam connecting rods, not all are created equal. Manley’s H-Beam Series stands out as a superior choice, offering exceptional quality at an economical price point. These connecting rods are meticulously crafted to meet the same high-quality standards as our renowned Sportsmaster® and Pro Series rods.
  • JE/SRP Pistons- SRP Professional pistons combine forged piston durability with modern performance technology for an extremely capable forged piston kit that doesn’t break the bank. Forged from 4032 aluminum, SPR Pro pistons experience minimal thermal expansion, making them perfect for a high-performance, reliable engine build from the track to the drag strip. All SRP Pro pistons include premium ring sets, wrist pins and locks. As with all JE Pistons products, SRP pistons are made 100% in the USA.
  • JE Pro Steel Rings – The JE Pro Steel Rings are designed to maximize horsepower through precision sealing of combustion pressure. This ring pack will have a carbon steel top ring for high boost applications.
  • Clevite H Bearings – These bearings were primarily developed for Nascar racing, but are well suited for High Performance applications as well. They’re especially good for high revving engines and getting the exact clearances needed with consistency.
  • Cylinder Heads – ATK LS3
  • Johnson Link Bar Lifters – 100% American made, Johnson leads the way in quality and performance when it comes to lifters.
  • ARP Head Studs – For ultimate clamping force under high boost!
  • Upgrades and Custom Builds Available.


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