Bill Mitchell Products BMP 085575 – Aluminum Engine Block Chevy 409 W Block 9.600 Deck, 4.250 Bore, Billet Caps


Bill Mitchell Products 409 W 357T6 Aluminum Engine Block Chevy 409 W Block 454 Mains, 9.600″Deck, 4.250″ Bore. Standard Cam(includes, Screw in Freeze plugs, Cam Plug, all dowel pins and Pipe plugs) 085575

Block Specifications:

Block Applications: The BMP Aluminum 409 blocks are designed to be a replacement for all OEM 409 blocks
Casting Number: BMP-409
Block Material: 357-T6 aluminum alloy.
Block Weights: BMP BBC Aluminum blocks with main caps, hardware and cylinder sleeves 150lbs
Deck Height: 9.600

Deck Thickness: .600” minimum

Cam Bearings: Accepts Standard Big Block Chevy Cam bearings. Rear cam plug is special to this block available under part # 701620. This part is
furnished with the block. Can be machined for a 55mm bearing

Main Bearings: Utilizes Big Block Chevrolet style main bearings.

Main Caps: Billet steel main caps. Center three caps have splayed studs. The front and rear caps are a straight studded design. All the main caps use
a ½” thread. Torque spec on main bolts both inner and outer is 110 ft. lbs. with oil.
Rear Main Seal: Standard Big Block Chevy two-piece rear main seal, Fel Pro # P29182 is used

Lifter Bores: Spread .100” from stock 409 location, Indexed 45° angle,.8437”O.D. May require an offset lifter depending on your combination.

Cylinder Bores: 4.290” ±.005” Cylinder bores are of a Siamese design. Sleeves are a replaceable, centrifugal cast ductile steel pressed in with a
.001” to .002” fit. Block is machined to incorporate an o-ring behind the sleeve to keep oil from traveling up between the sleeve and the block. Sleeves
do not protrude into the water and are considered a dry sleeve.
NOTE: It is very important that you draw down each and every sleeve to assure that it is seated prior to decking the block. Beating with a big
hammer and a block of wood is not acceptable due to the chance of sleeve bounce.

Cylinder Wall Thickness: Sleeve OD on all BBC blocks 4.685”+ approximately .200” aluminum surrounding the sleeve (except for between the
cylinders of course). These blocks can be safely bored to 4.560” for most applications but the engine builder must make the final decision based on the
application being built for.
Freeze Plugs: All aluminum blocks include screw in freeze plugs. Torque to 35 ft lbs with anti seize on threads and o-rings
Distributors: A 409 distributor can be used but you must turn down the bottom to BBC dimension or you can use a BBC distributor but it will need a
.300” spacer above the manifold.

Oil System Features: Priority main oiling. As is, block is set up for OE style internal oil pump. Block may be converted to a dry sump oiling system.

Stroke Clearance: Block accepts a std BBC crankshaft. Block will accept up to 4.250” stroke without block relieving.
Connecting Rods: Standard BBC

Pistons: BBC with 409 dome and valve notches

Water Jackets: Expanded for better cooling. O-ringed freeze plugs, screw-in style, BMP part # 701645. (supplied with all new blocks)

Oil Restrictors: Blocks use oil restrictor part # 701802-2.

Filtration: Integral mount for spin on filter. The oil filter mounting boss has been relocated to clear kickout style oil pans.

Oil Pan Rails: Solid (stock BBC width) can be clearanced for strokers. BBC Oil pan can be used
Cylinder Head Bolt Holes: The top row of head bolt holes should not in any way be modified and made any deeper. These holes are on an angle
that will converge into the cylinder. Any added depth with result in contact with the cylinder sleeve. Also, do not over torque these studs as they can
distort the cylinder.

Head Studs: ARP 134-4002 6Pt, 235-4202 12Pt Kits have 1.000″ coarse threads

Camshaft: 409 special w/BBC cam bearing journals
Timing Chain: Standard BBC

Timing Chain Cover: Standard BBC

Fuel Pump: Uses stock style fuel pump and stock length fuel pump pushrod. When using a billet aluminum fuel pump block off plate you may need to
modify it slightly for fit due to overall size.

Starter: Starter mounting pad is drilled for both straight across and stagger bolt patterns.

Bell Housing Pattern: Stock GM
Motor Mounts: Drilled and tapped for side and front mounts in OEM locations.

Gear Drives & Belt Drives: To prevent contact between oil galley plugs and belt drive or gear drive covers, it may be necessary to tap the oil galley
holes in the block deeper so the oil galley plugs will sit flush with the block, or you can use shorter plugs.
Water Pump: Standard 409


Weight 175 lbs
Dimensions 32 × 25 × 22 in


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