12480046 - SB2.2 (Nascar Bush Series) Chevy Small Block - 4.116"-4.185" Bore, 9.025" Deck, 2.45" Mains, 4 Bolt Main, Siamesed Bores

GM Performance Parts Race Blocks

Our blocks take the guess work out of what block you need to make big horsepower - that is competition tested in NASCAR BUSCH and NHRA competition eliminator! Only GM Performance parts can offer you such a huge selection of race blocks that have been precision CNC machined with tighter tolerances than our Bowtie blocks. These blocks feature full race prep machining, 4 bolt splayed main caps, and the very highest grade materials throughout. When your competition has spilled thier guts all over the racetrack, you'll still be in the show thanks to your GM Performance Parts race block.

Notes for all race blocks:

• Machined to .001" tolerances
• Cylinder decks, front and rear of case, oil pan rail surfaces and head dowel pins are blueprinted!
• Non standard cam bearings required (see notes below for details)
• Cam bosses are enlarged to allow machining for the use of larger cam bearings
• Extra thick main bearing bulkhead machined at 5 drgrees
• Premium quality studs and SAE 8620 steel main bearing caps
• Billet wet sump rear main cap can be adapted to dry sump with plugs
• Bearing cap inner bolts are spread .210" to allow machining for the use of 400 journal crankshafts
• Priority main oil system
• 2-piece rear main crankshaft and pre-1986 oil pan required
• Extra thick deck surfaces with blind tapped head bolt holes for improved head gasket sealing
• Cylinder bores have a nominal wall thickness of .340"
• .225" minimum xylinder bore wall thickness at 4.155" bore, sonic bore test data sheet included with each block
• These blocks may require clearencing of the tops of the lifter bores for some aftermarket mechanical roller lifters
• Lifter valley oil scavenging boss behind cylinder #8 below bell housing flange is not drilled and tapped
• Oil dipstick holes are not drilled

Specifications for this block:

• CNC machined, cast-iron NASCAR competition block
• 350 Main size
• 9.025" deck height
• 4-bolt NASCAR specific steel mains, 17 degree splayed caps on center three mains
• 4.115" rough bore
• 4.185" max bore
• Siamese bores
• Machined for 58mm roller cam bearings
• .875" lifter bores
• 6 AN coolant drains
• 45 degree 10AN front oil feed gallery scavange port
• AN O-ring pipe plugs
• 4 center lifter valley drains (drilled & tapped)
• Steam holes drilled between cylinders .750" below deck surface
• 1/2" NPT coolant hole on each side of block
• Dry sump only (no filter boss)
• Tested to over 800 HP