Dart's popular line of Big M2 blocks just got bigger and more competition focused, with five new part numbers. These new Big M2 block part numbers will feature 55mm roller cam tunnels, larger .904in lifter bores, doweled main caps and raised lifter oil galleries. These features represent the most demanded block upgrades requested by racers, now combined into convenient packages for easy ordering and to better meet our customer's and builder's needs

Dart 31223454 – Cast Iron Big M Sportsman Engine Block Chevy Big Block 10.200 Deck, 4.500 Bore, Ductile Caps

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.

Material: Superior iron alloy
Bore: 4.500″ (unfinished)
Bore/Stroke: 4.625″ x 4.750″ (max recommended)
Cam Bearing Bore ID: 2.120″
Cam Bearings: Specially-coated & grooved with three oil holes #32210030
Cam Bearing OS: +.010″, +.020″, +.030″
Cam Bearing Press: .002″
Cam Plug: 2.215″ shallow cup
Cylinder Wall Thickness: .300″ minimum @ 4.624″ bore
Deck Height: 10.200″
Deck Thickness: .625″ minimum
Fuel Pump: Mechanical pump provision
Fuel Pump Pushrod: STD BBC
Freeze Plugs: Press-in cup plugs 1-5/8″
Lifter Bores: SBC .8427″ to .8437″ +.300″ taller Gen V, VI style
Main Bearing Size: STD. BBC
Main Bearing Bore: 2.937″-2.983″
Main Caps: Ductile, 4 bolt, center 3 splayed
Main Cap Register: Deep stepped register on each side (no need for dowels)
Main Cap Press: .005″
Oil System: Wet sump, main priority oiling (can use dry sump)
Oil Pump Shaft: BBC shaft with wet sump
Oil Filter: Stock location
Oil Pan: Standard Pan rails
Rear Main Seal: Standard 2 piece Felpro 2918
Serial Number: On main caps and left front
Starter: Standard BBC
Stud Hole/Head: Blind holes
Timing Cover: Can use stock stamped steel or plastic
Torque: All 1/2″ bolts 105lbs
Weight: 4.500″-260lbs,