Manley 290300R SBC Rotating Assembly Stroke Bore Stroker Kit - 434 4.000 4.125

The Manley 290300R is a complete 434 cubic inch Small Block Chevy rotating assembly built around a 4.000" stroke and 4.125" bore combination. Precision internally balanced by Manley in-house, this stroker kit delivers race-proven reliability for high-performance street and competition builds.

Crankshaft:

• Manley Pro-Series 4340 forged steel lightweight crankshaft — 4.000" stroke, 350 main journals
• Non-twist design with fully profiled counterweights optimized for internal balancing
• Heat treated, stress relieved, shot peened, nitrided, and 100% magnafluxed for maximum durability
• Micro-polished journals with gun-drilled mains and lightened rod journals for reduced rotating mass

Connecting Rods:

• Manley 4340 forged steel H-beam rods — 6.000" center-to-center length
• 7/16" ARP cap screws (ARP 8740 standard; ARP 2000 optional for up to 1,500 hp)
• Bronze bushed small end; fully machined, heat treated, stress relieved, shot peened, and magnafluxed

Pistons:

• Manley 2618 forged aluminum Platinum Series pistons — 4.125" bore
• Premium chromoly wrist pins included

Rings & Hardware:

• Total Seal piston rings — 1/16" – 1/16" – 3/16" ring package

The 290300R is designed for use with 2-piece rear main seal blocks with 350 main journals. The complete assembly is precision balanced in-house at Manley, making it a direct drop-in foundation for a serious 434 SBC stroker build targeting the street/strip or competition market.