We Build a Tri-Power 427 for Today’s Driver
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Chevy made big-block crankshafts in two different strokes. The 396, 402, and the 427 all use a stroke of 3.76 inches. These are internally balanced crankshafts. The 454 uses a 4-inch stroke and is externally balanced. All the main-bearing journal diameters for the Mark IV big-blocks are 2.7482 to 2.7492 inches, with the rear main-journal diameter at 2.7478 to 2.7488 inches. The rod bearing’s journal diameters measure 2.1988 to 2.1998 inches, making the crankshafts interchangeable. We’ll be using a crankshaft with a stroke of 3.76 inches to make our engine a 427 just like the original. There are two different types of big-block crankshafts—cast or forged. You can tell the difference by the parting line on the crankshaft throws. The cast crankshafts will have a thin parting line where the two halves were joined to make the complete crankshaft, while the forged crankshaft will have a wider parting line. The 427 Corvette crankshafts are all forged steel. View Related Article
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