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Dart 31263344

Big Block Chevy Big M Engine Block 4.250" Bore 9.800" Deck Height

Dart 31263344

Part Number: 301-31263344

Big Block Chevy Big M Engine Block
  • 4.250'' Bore
  • 9.800'' Deck Height
  • Billet Steel Main Caps
  • $2,796.43
    Ships 11/16/16
    if Ordered Today
    Made In USA
    Truck Freight: $119.00
    Dart 31263344 Big Block Chevy Big M Engine Block 4.250" Bore 9.800" Deck Height $2,796.43

    Dart 31263344 Details

    Iron Blocks W/Billet Steel Main Caps


    Material: Superior Iron Alloy
    Bore: 4.250''
    Bore & Stroke: 4.625'' x 4.750'' max recommended
    Cam Bearing Bore ID: 2.1195'' - 2.1205''
    Cam Bearings: Special coated, grooved, with 3 oil holes
    Cam Bearing OS: +.010'', +.020'', +.030''
    Cam Bearing Press: .002''
    Camshaft Postion: Standard
    Cam Drive: Standard Timing chain, gear drive or belt drive
    Cam Plug: Standard BBC 2-7/32'' (2.218'' dia)
    Cubic Inch: 632'' max recommended
    Cylinder Wall Thickness: .300'' min @ 4.625'' bore
    Deck Height: 9.800''
    Deck Thickness: Adequate for all applications
    Fuel Pump: Mechanical pump provision
    Fuel Pump Pushrod: Standard BBC
    Freeze Plugs: Press in cup plugs
    Head Gasket: Fel-Pro 375-1037, 1047, or 1067
    Inner Head Stud: 2 slotted bosses per side
    Lifter Bores: BBC .8427'' - .8437''
    Lifter Galley: Raised .350'' for longer lifter bore
    Lifter Type: Roller - Gen VI (+.300'' longer), Solid - Mark IV
    Main Bearing Size: Standard BBC
    Main Bearing Bore: 2.937'' - 2.937''
    Main Caps: 4-bolt steel billet
    Main Cap Register: Deep stepped register on each side (No need for dowels)
    Main Cap Press: .005''
    Main Cap Bolts: All 1/2'', #2, #3, #4 have splayed outer bolts
    Oil System: Wet or Dry Sump - Main Priority Oiling
    Oil Galley, Main: Stepped, 9/16'' - 1/2'' - 7/16''
    Oil Galley, Filter-Main: 5/8''
    Oil Filter: Stock Oil Filter Location
    Oil Pan: Standard pan bolt pattern, extra bolt holes provided for strokers
    Rear Main Seal: Standard 2-piece seal, Fel-Pro 375-2918
    Rear Main Thrust Width: 1.622'' - 1.624''
    Serial Number: On main caps
    Starter: Mounts in standard location
    Stud Hole, Head: Blind holes
    Timing Chain/Gears: Standard
    Timing Cover: Stock Cover
    Torque Specs: All 1/2'' bolts - 105 lbs
    Weight: 4.250'' bore - 260 lbs


    Rear Main Seal Style
    Cam Bearings Included
    Cylinder Bore as Shipped (in.)
    Cylinder Bore Diameter (in.)
    Deck Height (in.)
    Engine Block Material
    Cast iron
    Engine Block Style
    Stock/OEM standard deck
    Engine Block Weight (lbs.)
    Finished Cylinder Bores
    Freeze Plugs Included
    Main Bearings Included
    Main Bolt Style
    Main Cap Fasteners Included
    Main Cap Material
    Main Caps Included
    Main Journal Type
    Sold individually
    Raised Cam Location
    Manufacturer's Part Number:

    Dart has reinvented the Rat Motor! Their cast-iron Big M big-block is a no compromise design that solves the problems that have plagued big-block racers for years. Working with top builders and Dart's own championship-winning Pro Stock engine department, they have designed a user-friendly block with the features you need today. For example, Dart redesigned the lubrication system to create a true ''priority main'' system that oils all of the main bearings before the lifters for extra reliability. The 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. The result: more oil at the bearings and pushrods where it's needed, and less power-robbing crankcase windage!

    Big-blocks are prone to head gasket failure in long spans between head bolts. Dart has added two head stud bosses on both sides of the lifter valley to take the place of the ''missing'' head bolts. The bosses are slotted so you can use studs instead of hard-to-install bolts. Dart machines these blocks in-house on precision CNC equipment to ensure quality and to eliminate the need for expensive ''blueprinting''. They have engineered the Big M to be the strongest, most reliable and easiest to build big-block on the market!

  • Siamesed Extra-Thick Cylinder Walls: Resists cracking and improves ring seal (minimum .300'' thick with 4.625'' bore).
  • Scalloped Outer Water Jacket Walls: Improves coolant flow around the cylinder barrels to equalize temperatures.
  • Four-Bolt Main Bearing Caps: In steel or ductile iron have splayed outer bolts for extra strength.
  • 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.
  • Oil Filter Pad: Drilled and tapped for an external oil pump.
  • Rear Four-Bolt Cap: Uses standard oil pump and two-piece seal - no adapter required!
  • Lifter Valley Head Stud Bosses: Prevent blown head gaskets between head bolts.
  • External Block Machining: Reduces weight without sacrificing strength.
  • Simplified Install : Fuel pump boss, clutch linkage mounts and side & front motor mounts simplfy installation on any chassis.
  • Dual Oil Pan Bolt Patterns: Fits standard and notched oil pans.
  • Bellhousing Flange and Rear Main Bearing: Reinforced with ribs to resist cracks.
  • Note: Does not include cam bearings, freeze plugs, or dowels.Tech Tip - Oiling System

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