IRN BIG M SPRTSMN DUCTILE

Dart Big M Sportsman Iron Engine Block features ductile iron 4-bolt mains caps for ultimate bottom-end strength, siamesed extra thick cylinder walls to resist cracking and improve ring seal, and a true priority main oil system that lubricates the main bearings before the lifters. It uses +.300 in. tall GM Gen VI style lifters and has a crankshaft tunnel with clearance for a 4.500 in. stroke with steel rods without grinding. The main bearing caps have splayed outer bolts for extra strength. The stepped main oil gallery (9/16 in. to 1/2 in. to 7/16 in.) increases the flow of oil to the crankshaft at high RPM, and the front oil crossover eliminates internal oil leaks around the distributor shaft. Lifter valley head stud bosses prevent blown head gaskets, and it has dual oil pan bolt patterns to fit standard and notched oil pans. Made from 220 BHN cast iron material with .842 in. lifter bores and press-fit freeze plugs. Designed for a 2-Piece rear main seal. Block parts kit sold separately (301-32000002). This part is only legal for sale and use on Uncontrolled (Non-Emissions Controlled) Vehicles or on vehicles used solely for the purposes of closed competition racing.