103523480 - Eagle ESP Cast Steel Crankshafts Details

Chevrolet - Small Block

GM engineers redesigned the crankshafts used in production small-block V8 and V6/90° engines in 1986 to use a leak-resistant one-piece rear seal. This change from a two-piece seal to a one-piece seal required a change in the bolt pattern on the crankshaft flywheel flange. The engine block, oil pan, pan gaskets, and flywheel were also redesigned to accommodate this one-piece seal. The bolt circle on pre-1986 production crankshafts is 3.58'' in diameter. 1986 and later cranks have a 3.00'' bolt circle. In addition, all cranks which use a one-piece seal require a counterweighted flywheel for proper engine balance.