1.640 Dual Valve Springs

The Manley 1.640 Dual Valve Springs are precision-engineered components designed for high-performance engine builds where valve control and reliability under extreme conditions are non-negotiable. Built for enthusiasts and professionals who demand consistent valve seating across aggressive camshaft profiles, these dual springs excel in naturally aspirated, supercharged, and turbocharged applications.

Whether you're building a weekend track car or a street engine that sees sustained RPM ranges beyond stock specifications, the 1.640 seat diameter provides the correct interface for compatible cylinder head configurations and ensures predictable valve motion without chatter or float. Manley's dual-spring design uses two concentric springs working in harmony to manage both low-lift and high-lift spring rates, maintaining valve stability across the entire lift curve and eliminating the resonance issues that can plague single-spring configurations at elevated RPM.

Constructed from premium heat-treated alloy steel, these springs maintain their mechanical properties under sustained thermal cycling and resist fatigue failure—critical when camshaft lobe profiles demand rapid valve acceleration and extended valve timing events. The inner and outer springs are engineered with different wire diameters and preloads, allowing the assembly to deliver sufficient load for positive valve closure while resisting coil-bind and surge that would compromise durability and engine longevity.