Dart Big M2 Engine Block Big Block Chevy 4.500" Bore, 9.8" Deck Height
- Part # 31213444
- Material: Superior Iron Alloy
- Bore: 4.500"
- Bore & stroke: 4.625" x 4.750" (max recommended)
- Cam bearing bore ID: 2.120" Std.
- Cam bearings: Coated, grooved, w/3 oil holes PN# 32210030 (Not included)
- Cam bearing O.S. +.010", +.020", +.030" available *Call for Part numbers
- Cam bearing press: .002"
- Camshaft position: Standard
- Cam Drive: Timing chain, Gear drive & Belt drive
- Cam Plug: Standard BBC 2.215" P/N: 32520000
- Cubic Inch: 632" (Max Recommended)
- Cylinder Wall Thickness: .300" min @ 4.625" bore
- Deck Height: 9.800"
- Deck Thickness: Adequate for all applications
- Dist. Tap Hole Valley: None
- Fuel Pump Boss: Mechanical pump provision
- Fuel Pump Pushrod: Std. BBC
- Freeze Plugs: Std. Press in cup plugs 1 5/8 “dia.
- Head Bolt Pattern: Std. BBC Big M Bolt Pattern
- Inside Head Studs: P/N: 64210240 (Not included)
- Lifter Bores: BBC .8427" - .8437" + .300 Taller Gen V, VI style
- Main bearing size: Std. BBC
- Main bearing bore: 2.937" – 2.938"
- Main caps: Steel Billet or Ductile Iron (Sportsman) 4 bolt
- Oil system: Wet or Dry Sump - Main Priority Oiling
- Oil Galley, main: Stepped, 9/16" – 1/2" – 7/16"
- Oil Cooler Holes: None (Can use aftermarket inline)
- Oil Galley, filter main: 5/8"
- Oil Filter: Stock oil filter location
- Oil Pan: Std. BBC bolt pattern & Stroker pattern at mains
- Rear Main Seal: STD 2 pc seal / Felpro# 2918 or 29182
- Hyd. Roller Provisions: None
- Serial No. On main caps / Front passenger side below deck
- Starter: Mounts in standard location
- Stud & bolt holes: Blind tapped
- Tapped Holes: Std. English Thread & Pitch
- Timing chain / gears: Std. BBC
- Timing Cover: Gen IV / V stock 10 bolt cover
- Torque Specs: All ½" bolts – 100 ft lbs w/CMD #3 high pressure lube
- Weight: 4.250" bore (280lbs) – 4.500" bore (260lbs)
- 4.600" bore (250lbs)
About the Dart Big M2
Dart engineered the Big M to be the strongest, most reliable, and easiest to build big block on the market.
The Dart Big M2 is designed from the ground up as a true racing engine block which can be used with standard off the shelf big block components. The Big M2 is cast from premium high strength Iron and beefed up in all the critical areas. A competition oiling system ensures adequate lubrication to the main bearings at high RPM.
• Standard 9.800”, 10.200” and 10.400″ 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)
• Available in .400” raised cam
• Uses +.300” tall GEN VI style lifters. Modified cation for MRK IV style available
• 4-bolt main bearing caps in steel or ductile iron have splayed outer bolts for extra strength
• Lifter valley head stud bosses help prevent blown head gaskets
• Easy to install AN fitting oil gallery plugs