Crankshaft – Forged 4340 Steel


  • Forged 4340 steel
  • 2.100″ rod journals
  • 350 standard size mains
  • Used to create 383-cubic-inch engines with 3.800″ stroke
SKU: 12489436 Categories: ,


P/N 12489436

  • Forged 4340 steel
  • Used to create 383-cubic-inch engines with 3.800″ stroke
  • Rod journals are 2.100″
  • Mains are standard 350 size

Notes: Should be used with connecting rods P/N 19169670, bearing kit P/N 17800761, standard pistons P/N 88962748 or 0.030″ oversize pistons P/N 88962749, balancer P/N 12498008, and 1986-and-later one-piece crank seal design flywheel or flexplate.


Forged 4340 Steel Crankshaft

12489436 Chevrolet Crankshaft

For 383 Engines

A crankshaft is that massive piece of convoluted steel that holds the whole engine together. An engine is essentially a pump, and without a strong crankshaft, the pump won’t work. GM puts the same top-quality engineering and manufacturing processes into its crankshafts as it does all its parts. These crankshafts are the same ones used in Chevrolet Performance crate engines. The crankshafts are available in cast iron and forged steel. Forged crankshafts should be used for higher-horsepower applications.

Prop65WARNING: These auto parts can expose you to chemicals including phthalates and lead. Installing or using these parts can expose you to other parts containing these chemicals and to engine exhaust, which are known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to