Manley 290960HX SBC Rotating Assembly Stroke Bore HX Bearings - 383 3.750 4.030

The Manley 290960HX is a complete rotating assembly engineered for the Small Block Chevy 383 stroker platform, featuring a 3.750" stroke and 4.030" bore (+0.030" oversize). The HX suffix designates Clevite® HX-Series main bearings with an additional .001" extra clearance, making this kit ideal for engine builds requiring slightly looser main bearing tolerances.

Built to handle serious street and race applications, this kit centers around a lightweight 4340 forged steel crankshaft paired with 4340 forged steel H-Beam connecting rods secured with ARP cap screws. The pistons are Manley's 2618 forged aluminum Platinum Series units with premium chrome moly wrist pins — a high-strength alloy chosen for boosted and high-RPM applications.

Kit Includes:

• Lightweight 4340 forged steel crankshaft — 3.750" stroke
• 4340 forged steel H-Beam connecting rods with ARP cap screws
• 2618 forged aluminum Platinum Series pistons — 4.030" bore
• Premium chrome moly wrist pins
• High-performance piston rings (Total Seal)
• Clevite® "H" Series rod bearings (narrowed)
• Clevite® "HX" Series main bearings (+.001" extra clearance)

Key Specifications:

• Engine Family: Small Block Chevy (SBC)
• Displacement: 383 cubic inches
• Stroke: 3.750"
• Bore: 4.030" (+0.030" oversize)
• Bearing Option: HX Series — +.001" extra main bearing clearance
• Rod Material: 4340 forged steel H-Beam
• Piston Material: 2618 forged aluminum

Note: Per Manley documentation, Small Block Chevy 350/400-based rotating assemblies in this series are unbalanced from the factory. Precision balancing (Manley P/N 04000-1 or equivalent) is required before installation.