Dart Big M Sportsman Chevy Big Block Iron Block – 4.600 in. Bore, 10.200 in. Deck (31223654)

Dart engineered the Big M to be the strongest, most reliable, and easiest to build big block on the market. The Dart Big M2 is designed from the ground up as a true racing engine block which can be used with standard off the shelf big block components. The Big M2 is cast from premium high strength Iron and beefed up in all the critical areas. A competition oiling system ensures adequate lubrication to the main bearings at high RPM.

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 walLS2 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 1/2“ to 7/16“) increases the flow of oil to the crank at high RPM, and our front oil crossover eliminates internal oil leaks around the distributor shaft; Lifter valley head stud bosses prevent blown head gaskets; Dual oil pan bolt patterns fit standard and notched oil pans; Parts kit sold separately