Race Prep Dart Big M Sportsman Block 31223444 BBC 4.500 Bore

CNC-Motorsports takes great pride in offering a fully race prepped Dart Big M sportsman block blue-printed to race specifications that is ready for you to assemble. 

• Check and align hone mains if needed, chamfered main parting lines
• Bell housing surface squared to crankshaft center-line
• Stroker clearance to 4.250 stroke
• Parallel square deck the deck surface to your desired deck height
• Bottom of the cylinders chamfered
• Top of the cylinder bore chamfered
• Block de-burred to eliminate sharp edges and casting slag
• Freeze plug holes and rear cam hole are chamfered
• All bolt holes and oil galley holes chamfered
• Oil galley holes tapped
• Head and main bolt holes tapped
• Chamfered distributor hole and lightly ball honed to eliminate high spots
• Hone the block with torque plates to your piston bore size and verified with a profilometer
• Top of lifter bores chamfered
• Lifter bore checked and honed to your set of lifters you will be using in your build
• Install Cam Bearings and Freeze Plugs
• Block is cleaned and ready to go
  
  Dart Big M Sportsman Block has reinvented the Rat motor. Darts new cast iron Big M big block is a no-comparison design that solves the problems that have plugged big block racers for years. Dart has engineered the Big M to be the strongest, most reliable, and easiest to build big block on the market. Features Simaesed extra thick cylinder walls resist cracking and improve ring seal, Scalloped outer water jacket walls improve coolant flow around the cylinder barrels to equalize temperature. Four bolt main bearing caps have splayed outer bolts. Crankshaft tunnel has clearance for 4.500 Stroke crankshaft. Rear four bolt cap uses standard oil pump and two piece rear seal.