Chevrolet Performance Small Block Bare Block 12691718

This engine block is used in 1986-99 Gen I heavy-duty applications.It has 4.00" diameter cylinder bores and four-bolt main bearing caps.This block is machined for a one-piece rear crankshaft seal.These blocks weigh 197 lbs.Cylinder wall thickness is the same as current production engines.The lifter valley is machined for hydraulic roller and flat tappets.Crankshafts with two-piece seals can be installed with adapter P/N 1005118.This block includes: main bearing caps, main bearing cap bolts, freeze plugs, oil gallery plugs,and cam bearings.
4.000"-4.030" Bore, 9.025" Deck, 2.45" Mains, 4 Bolt Main, Non-Siamesed Bores, 1 Piece Rear Main Seal