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Bill Mitchell Products BMP 086515 – Aluminum Engine Block Chevy LS Block 9.240 Deck, 4.115 Bore, Billet Caps


Bill Mitchell Products LSC 357T6 Aluminum Engine Block Chevy LS Series Std Mains, 9.240″Deck, 4.115″ Bore, Billet Caps, Standard Cam(includes, Screw in Freeze plugs, Cam plug, All dowel pins and Pipe plugs) 086515

Block Specifications:

Block Applications: The BMP aluminum blocks are designed to be a high Performance replacement for the GM LS series blocks.

Casting Number: BMP-045A ( 9.800” ) / BMP-045B ( 9.240” )

Block Material: Aluminum 357T6 aluminum alloy
Block Weight: 135lbs w/ caps and sleeves
Deck Height: 9.240” (Standard Chevrolet) or 9.800”

Deck Thickness: .600 minimum.
Cam Bearings: Durabond Part # CH-23 or equivalent. As of 2024, REV.2 Durabond Part# GM25, GMP25, GM25T
Note: When installing, BE SURE the oil hole in the bearings aligns with the oil feed hole
Main Bearings: Standard LS main bearings.

Main Caps: All five main caps are four bolt and cross bolted billet steel caps. The cap studs are 7/16” thread. The outer cross bolts are 8mm x 1.25”
thread. Torque specs on studs are: 75 ft. lbs. and 30lbs on cross bolts with oil.

Lifters: Standard GM tie bar lifters

Lifter Bores: Standard location, Indexed. Lifter bore size is standard Chevy diameter .8437”.

Bore Center: Standard 4.400″

Cylinder Bores: 3.990” or 4.115” standard. Cylinder bores are of a Siamese design. Sleeves are a replaceable, centrifugal cast ductile steel pressed in with a .001” to -.002” fit. Sleeves do not protrude into the water and are considered to be a DRY sleeve.

Cylinder Wall Thickness: Sleeve OD on all LS blocks are 4.280”+ approximately .200” aluminum surrounding it (except between the cylinders of
course). These blocks can safely be bored to 4.165” but the engine builder must make that final call based on the application the engine is being built for.

Freeze Plugs: All aluminum blocks include screw in freeze plugs. Torque to 35lbs with anti seize on threads and o-rings BMP part#
Distributors: N/A

Oil System Features: Priority main oiling. Block has provisions to be converted to a dry sump oiling system.

Stroke Clearance: Will accept a 4.250” stroke crank with steel rods. Larger strokes or aluminum rods may require additional clearance and rerouting
the oil to the outside of the block.
Oil Restrictors: Due to the very efficient oiling system of the BMP LS aluminum block a std volume oil pump should be used and in addition to this oil
restrictors of .150” should be the minimum starting point to control how much oil pressure your engine ultimately has. This is only a recommendation and
should ultimately be the decision of the engine builder.

Filtration: Stock
Oil Pan Rails: Solid (stock width) can be clearanced for strokers. When clearance is required for strokes larger then 4.500”, depending
on the connecting rod used the notch may protrude into the internal oil passage but can be corrected by an external oil line utilizing the
tapped holes in the side of the block.

Cylinder Head Bolt Holes: Standard GM LSX Bolt Pattern. Use of World Products LS7 heads using the extra bolt holes will
need modifications to utilize the extra bolts.

Camshaft: Std camshaft location
Fuel Pump: N/A
Rear Main Seal Block Cover Plater: Stock GM rear cover (GM Part # 12572014, 12556105). CAUTION> the left side inner
most bolt hole is tapped very shallow due to oil passage. You must shorten the bolt. DO NOT MAKE THE HOLE
Starter: Std Starter

Motor Mounts: Drilled and tapped for both stock mounts in OEM locations and conventional SBC for a retro fit into older cars.
Bell Housing Pattern: Stock GM

Gear Drives & Belt Drives: N/A
Accessory Brackets: Due to OE block design variations over the years some of the bolt holes in the BMP block may not be drilled or tapped deep
enough to allow factory fasteners to completely seat against the heads. It is advisable before final assembly to verify whether the OE fasteners need

Water Pump: Stock LS


Weight 176 lbs
Dimensions 36 × 36 × 25 in


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