.313" x 4". Excellent 59 L block. Hard valve seats. Hot tanked more than 20 years ago when good blocks were more plentiful. Looking good now after 48 hours in the Evaporust tank. Prepping block for paint. Milled the block to insure a good head gasket surface. Offy pistons & rings. Stainless steel valves. Iskenderian 400JR. Isky valve springs. Johnson hollow lifters. New guides. Oil pan & new oil pump. $5,950. 00. Use your 2 bolt or 3 bolt front cover. 704 788 8225