Dart Big M Sportsman Iron Engine Block BBC - 31213654

#312136544.600" Bore10.200" Deck HeightBillet Steel Main Caps Dart engineered the Big M to be the strongest, most reliable, and easiest to build big block on the market. With deck heights of 9.800” and 10.200” and bore sizes up to 4.600”, the Big M gives you the versatility to build a wide variety of engine combinations. The Big M is fitted with Billet Steel 4-bolt main caps for ultimate bottom end strength. The Sportsman block is fitted with Ductile Iron 4-bolt main caps. FEATURES• Standard 9.800” and tall 10.200” deck heights.• Standard 4.250”, 4.500”, 4.560” or 4.600” bore sizes with siamesed extra thick cylinder walls to resist cracking and improve ring seal (minimum .300” thick with 4.625” bore).• Uses +.300” tall Gen VI style lifters. Modification for Gen IV style available.• 4-bolt main bearing caps in Ductile Iron have splayed outer bolts for extra strength.• True priority main oil system lubricates the main bearings before the lifters. Our stepped main oil gallery (9/16“ to 1/