Big M Chevy Big Block Iron Block – 4.250-4.600 In. Bore, -.800-10.200 In. Deck

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.

Features

• 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 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 fl ow 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 fi t standard and notched oil pans.
• Big M: Parts kit included (Part# 32000039).
Parts kits do not include cam bearings.

BIG M - IRON

BIG M SPECS
Material: 220 BHN Cast Iron
Deck Height: 9.800” to 10.200”
Cylinder Bores: 4.250” to 4.600”
Main Caps: Steel
Cam Location: Standard
Lifter Bores: .842”
Freeze Plugs: Press fi t
Rear Seal: 2-Piece
Weight: 250-280 lbs.

31213344 Big M Iron Std. Steel Std. 9.800” 4.250”
31213354 Big M Iron Std. Steel Std. 10.200” 4.250”
31213444 Big M Iron Std. Steel Std. 9.800” 4.500”
31213454 Big M Iron Std. Steel Std. 10.200” 4.500”
31213544 Big M Iron Std. Steel Std. 9.800” 4.560”
31213554 Big M Iron Std. Steel Std. 10.200” 4.560”
31213644 Big M Iron Std. Steel Std. 9.800” 4.600”
31213654 Big M Iron Std. Steel Std. 10.200” 4.600”