Dart Big M Iron Engine Block Big Block Chevy 4.250 in. Bore
301-31213354
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Iron Blocks W/Billet Steel Main Caps
Features:
- Ductile iron 4-bolt mains caps for ultimate bottom-end strength
- Siamesed extra thick cylinder walls to resist cracking and improve ring seal (minimum .300 in. thick with 4.625 in. bore)
- Uses +.300 in. tall GM Gen VI style lifters
- Crankshaft tunnel has clearance for a 4.500 in. stroke with steel rods without grinding
- Main bearing caps have splayed outer bolts for extra strength
- True priority main oil system lubricates the main bearings before the lifters
- Stepped main oil gallery (9/16 in. to 1/2 in. to 7/16 in.) increases the flow of oil to the crankshaft at high RPM, and 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 fit standard and notched oil pans
- 220 BHN cast iron block material
- .842 in. lifter bores
- Press-fit freeze plugs
- 2-Piece rear main seal
- Includes block parts kit 301-32000002 - coated cam bearings, freeze plugs and dowel pins
Specifications:
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 Position: 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: 10.200''
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 - 280 lbs
Specifications:
Motor Vehicles
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