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Product Summary

350, 350 mains Main Journal Style, 3.480" Engine Stroke

  • Crankshaft features straight shot and chamfered oil holes
  • There are lightening holes in all rod throws
  • Pistons feature a 2618 aluminum alloy construction
  • Connecting rods have full floating pin in silicon bronze bushings
  • Main and rod bearings feature 40 Vickers hardness to resist overlay migration and extrusion

Comes as a Kit

Key Specs

MFG. Part #9151220
BrandSpeedway Motors
Connecting Rod TypeH-Beam
Piston StyleFlat Top
Piston MaterialForged Aluminum

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Speedway Motors 9151220 Details

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. 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 C rings.

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
  • KB Signature Series 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
    • C/R 58cc=11.2, 64cc=10.4, 76cc=9.1
      Piston/Pin Weight: 634 g
      Rod Length: 5.7"     
  • Speedway 4340 H-beam Connecting Rods
    • Full floating pin in silicon bronze bushing
    • Precision bolt bushings to positively locate cap
    • 5.7" lengths
    • 622 grams
    • Weight matched set of 8 rods
  • King HP Series Main & 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
  • Chevy 350: 4.000" bore x 3.48" stroke

Item Details

Flat top, 500 g.

Speedway Motors 9151220 Specifications

KEY SPECS
MFG. Part #9151220
BrandSpeedway Motors
Connecting Rod TypeH-Beam
Piston StyleFlat Top
Piston MaterialForged Aluminum
GENERAL
Main Journal Style350 mains
Engine Stroke3.480"
Connecting Rod Length5.700"
Connecting Rod MaterialForged 4340 Steel
Connecting Rod Weight622 grams
Connecting Rod Bolt Diameter7/16"
Piston Weight499 grams
Piston Ring StyleC
Crankshaft MaterialForged 4340 Steel
Rear Main Seal Style2-piece
Wrist Pin Diameter.9272"
Wrist Pin Weight135 grams
Main Journal Diameter2.448"
Rod Journal Diameter2.10"
Bearing ConstructionBi-metal
Bearing UndersizeStandard
Narrowed BearingYes
Coated BearingNo
Sold in QuantityKit