Forged 421 SBC Stroker Kit Rotating Assembly, 400 Mains, 6" Rod

Speedway introduces forged rotating assemblies, with an optional balance job. Includes new 2-pc rear main seal crank, rods and pistons. Cranks are new so they use standard size bearings.

All Scat 4340 cranks are 2-piece rear main seal, internally balanced and weigh approximately 51-55 lbs.  All balancing is done with our state-of-the-art Hines balancer by race mechanics with over 30 years of experience!  A kit purchased with the optional balance job will ship in 24-48 hours (must be purchased separately, part # 91510201). These rotating assembly engine rebuild kits may require additional charges for heavy metal.

If you are going to run this crank in a sprint car motor, you must have the crank flange turned down prior to balancing the crank to allow it to go through the motor plate. 

NOTE: Piston rings are not included and must be purchased separately. Use Style E rings.

50 cc 14.0:1 compression ratio

Kits feature: 

• Scat 4340 Forged Steel Crankshaft   
  
  • Standard size journals
  • Straight shot and chamfered oil holes
  • Nitride hardened and shot peened
  • Lightening holes in all rod throws
  • Large radius on all journals
• ICON Forged Pistons 
  • 2618 aluminum alloy construction
  • T-6 heat treated 
  • 4.000" bore pistons available in standard, .030, .040, or .060 sizes
  • 4.125" bore pistons available in .030 or .040 sizes
• Speedway 4340 H-beam Connecting Rods
  • Full floating pin in silicon bronze bushing
  • Precision bolt bushings to positively locate cap
  • 6.0" lengths
  • 634 grams
  • Weight matched set of 8 rods
• King HP Series Main and Rod Bearings
  
  • 0.015" thick top layer for superior macro particle embedability and conformability
  • 40 Vickers hardness to resist overlay migration and extrusion
  • 450°F heat threshold for superior protection against friction and overheating
  • Mains are 3/4 grooved for improved oiling to the rod journals
  • Bi-metal aluminum silicon alloy featuring fine micro-bore finish

Kits feature: 

• Scat 4340 Forged Steel Crankshaft   
  
  • Standard size journals
  • Straight shot and chamfered oil holes
  • Nitride hardened and shot peened
  • Lightening holes in all rod throws
  • Large radius on all journals
• ICON Forged Pistons 
  • 2618 aluminum alloy construction
  • T-6 heat treated 
  • 4.000" bore pistons available in standard, .030, .040, or .060 sizes
  • 4.125" bore pistons available in .030 or .040 sizes
• Speedway 4340 H-beam Connecting Rods
  • Full floating pin in silicon bronze bushing
  • Precision bolt bushings to positively locate cap
  • 6.0" lengths
  • 634 grams
  • Weight matched set of 8 rods
• King HP Series Main and Rod Bearings
  
  • 0.015" thick top layer for superior macro particle embedability and conformability
  • 40 Vickers hardness to resist overlay migration and extrusion
  • 450°F heat threshold for superior protection against friction and overheating
  • Mains are 3/4 grooved for improved oiling to the rod journals
  • Bi-metal aluminum silicon alloy featuring fine micro-bore finish

• 415/421-ci SBC (3.875-inch stroke)
  • Displacement: 421 ci
  • Bore x Stroke: 4.155 x 3.875 inches
  • Compression: 10.7:1
  • Rod: 6.00-inch