Dart 31273354V Big M Block
Big M Sportsman Block
With multiple deck heights and bore sizes up to 4.600, the Big M
Sportsman block gives you the versatility to build a wide variety
of engine combinations. A true priority main oiling system oils the
main bearings before the lifters for extra reliability.
- Standard 9.800 and tall 10.200 deck heights available for
- Standard 4.250 , 4.500 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.
- Scalloped outer water jacket walls improve coolant flow around
the cylinder barrels to equalize temperatures.
- 2 bolt front and rear and 4 bolt interior ductile iron main
caps have splayed outer bolts for extra strength OR 4
bolt billet steel main caps have splayed outer bolts for extra
- Crankshaft tunnel has clearance for a 4.500 stroke crank with
steel rods without grinding.
- 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
- Oil filter pad is drilled and tapped for an external oil
- Available in traditional Gen IV style, or in Gen V
or Gen VI style with one piece rear seal.
- Lifter valley head stud bosses prevent blown head gaskets.
- Rear main cap uses standard oil pump and two piece seal no
- Mechanical fuel pump boss, clutch linkage mounts, and side and
front motor mounts simplify installation in any chassis.
- Dual oil pan bolt patterns fit standard and notched oil
- Coated cam bearings, freeze plugs and dowels are included.