Dart 31253754 – Cast Iron GEN VII 8.1 Engine Block Chevy Big Block 10.236 Deck, 4.625 Bore


Dart 31253754 – Cast Iron GEN VII8.1 Engine Block Chevy Big Block 10.236 Deck, 4.625 Bore

The Gen 7 8.1/8.8 liter big block was used in numerous marine and truck applications. Up until now, there have been very limited options for upgrading its performance potential.

Dart’s new Gen VII block is available with full water jackets including between the cylinder bores, or with siamesed bores to enable larger displacements. The water block is available with a 4.350” bore diameter, and the siamesed bore blocks can be bored to 4.625” diameter.

Standard 10.236” deck height.

• 4.250” and 4.350” bore water blocks.

• 4.250”- 4.625” bore sizes for siamese blocks.

• Provision for factory crank sensor.

• Uses Gen VI timing cover and oil pan.

• Blind head bolt holes.

• Lifter valley bosses for OE style roller lifters and retainer.

• Clutch linkage mounts, side and front motor mounts simplify installation in any chassis.


Material: Superior Iron Alloy

Bore: 4.250″ through 4.625

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

Cam bearing O.S. +.010″, +.020″, +.030″

Cam bearing press: .002″

Camshaft position: Standard

Cam Drive: Timing chain, Gear drive & Belt drive

Cam Plug: Standard BBC 2.215″ diameter

Cubic Inch: 638 Max recommended

Cylinder Wall Thickness: .300″ Min @ 4.625″ bore

Deck Height: 10.232″ (259.89mm)

Deck Thickness: Adequate for all applications

Dist. Tap Hole Valley: Yes

Fuel Pump Boss: None

Fuel Pump Pushrod: None

Freeze Plugs: Std. Press in cup plugs 1 5/8″

Head Bolt Pattern: Std GM

Inside Head Studs: None

Lifter Bores:.8427″ – .8437″ Machined for Gen 7 8.1L GM Hyd Roller

Main bearing size: Std BBC

Main bearing bore: 2.937″ – 2.938″

Main caps: Ductil iron, 4 bolt

Oil system: Wet or dry sump – Main priority oiling

Oil Galley, main: 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:8.1L Metric bolt patterned oil pan

Rear Main Seal1 piece, No gasket groove Felpro 2920

Hyd. Roller Provisions: Yes

Serial No. On Main Caps, Front passenger side below deck

Starter: Mounts in standard location

Stud & bolt holes: Blind Tapped

Tapped Holes: Metric thread & Pitch

Timing chain / gears: Std BBC GEN VI/GM 8.1L

Timing Cover: GEN VI stock 6 bolt cover or GM 8.1L

Torque Specs: All 1/2″ – 105lbs

Weight: 4.250″ bore (295lbs)

            4.350″ bore (280lbs)

Weight 295 lbs


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