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.

• 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 steel or 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.
• Big M Sportsman: Parts kit sold separately.
• Big M: Parts kit included.