Chevy V-8 Crankshaft Journal Sizes

There is a lot of misinformation on the internet about these numbers. We have taken the time to verify the data as much as possible. There still may be errors. Please lets us know if you find one.

Journal sizes are factory standard sizes. Your crankshaft journals may have been previously cut down by a machine shop. Make sure the crank you have is matched to your block. Blocks were made with specific journal sizes. Putting a small or medium journal, small-block crank into a medium or large journal, small-block block requires crank bearing spacers or special thick, aftermarket bearings

Chevy Small Block Journal Sizes

Gen. I, Small Journal

Gen. I, Medium Journal (Includes Vortec 305,350 to 1998.)

Gen. I, Large Journal

383, Gen. I, Non-Factory

Gen. I, 400 Crank in a Gen. I, 350 Block. Crank mains cut down.

377, Gen. I, Non-Factory

Gen. I, 350 Crank in a Gen. I, 400 Block. Spacer or Thick mains bearings.

Gen. II, Medium Journal

Includes: L99 265, LT1 350, LT4 350

302, Gen. II, Non-Factory

Gen. II, 265 L99 Crank in a Gen. II, 350 Block.

Gen. III

Includes: 1979-05 LS1 Corvette, Firebird, Camaro.

Corvette ZR1, LT5, DOHC.

Gen. II, 265 L99 Crank in a Gen. II, 350 Block.

Chevy Big Block Journal Sizes

T = Tall Deck

Chevy 348-409 W Journal Sizes