Chevrolet and GM Performance Parts - Small-Block Chevy Small Bore Bow Tie 2-Bolt Bare Block

Chevrolet - SBC CAST IRON BOW TIE BARE BLOCK (3.875” BORE)

This updated design has a decidedly different appearance, but retains its original part number. New tooling procedures have significantly improved the quality and durability of this third-generation casting. This heavy-duty cast iron Small Block Chevrolet Bow Tie block has rough-bored 3.875” diameter cylinders, which can be bored to a maximum diameter of 4.030”. This block is recommended for maximum effort competition engines.

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Updated 09-08-2004.

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BOW TIE SMALL-BLOCK BARE BLOCK NAVIGATION

Street 10051181	Street 10051183	Amateur Comp. 10185047	Sportsman 12480047	Sportsman 12480049
Racing 24502501	Racing 24502503	Racing 24502525	SB2 / SB2.2 24502600	Racing 24502650
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DESCRIPTION

Small Bore Bow Tie 2-Bolt Bare Block

P/N 10051181
     This updated design has a decidedly different appearance, but retains its original part number. New tooling procedures have significantly improved the quality and durability of this third-generation casting. This heavy-duty cast iron Bow Tie block has rough-bored 3.875” diameter cylinders, which can be bored to a maximum diameter of 4.030”. This block is recommended for maximum effort competition engines. The deck surfaces are thicker than production blocks, and the head bolt holes are blind tapped to improve head gasket sealing. The main bearing bulkheads are .900” thick and the front and rear bulkheads are reinforced with strengthening ribs.
     The updated design on this Bow Tie block’s oil galleries now extend flush to the front and rear faces of the cylinder case and can interfere with some camshaft drive systems. Therefore, timing system clearance should be checked before engine assembly. The revised Bow Tie block has a boss below the bellhousing flange behind the #8 cylinder that can be drilled and tapped for lifter valley oil scavenging. Oil drainback holes in the lifter valley are drilled. The updated design provides more consistency in the thickness of the cylinder walls and water jackets. The cylinder bores have a nominal wall thickness of .340” at the casting parting line (measured 2” below the deck surface).
     Technical Notes: Oil dipstick hole is not drilled and the lifter holes are finish bored to production diameter .842”. Two-bolt main bearing caps are installed to simplify the installation of the heavy-duty steel main caps with splayed outer bolts. Bow Tie blocks are designed for crankshafts with 2.45” diameter main bearing journals. The Bow Tie casting block P/N 10051182 is machined for a one-piece rear main bearing seal used on 1986 and later production small-block Chevrolet V8s. Crankshafts designed for two-piece rear main seals can be installed in Bow Tie blocks using crankshaft seal adapter P/N 10051118. These blocks weigh 187 lbs.

SPECIFICATIONS:

Block Material:
Cylinder Wall Type:
Cylinder Deck Height:
Cylinder Bore Range:
No. Bearing Cap Bolts:
Cap Bolt Orientation:
Bearing Cap Type:

Cast Iron
Non-Siamesed
9.025”
3.875”-4.030”
2
Straight

Crankshaft Journal Dia.:
Oil Sump Type:
Crankshaft Seal Type:
Design Max. Stroke:
Weight (lbs. - bare):
Intended Max. Hp @ RPM:
Intended Usage:

2.45”
Wet
1 piece
3.75”
197
375 @ 5750
Street