1989-1998 Cummins 5.9L 12V Manton Conical Valve Spring Kit (D-105-KIT-12V)

Upgrade your 12V 5.9L engine with Manton Heavy Duty Conical Springs, Billet Retainers & Lock Kit.

Ideal for engines running over 40psi and 3,700rpm; stronger pushrods recommended for this setup.

Protects valves from being pushed open under high boost conditions, enhancing efficiency and longevity.

Engineered for high boost capability and maximum valve train stability.

Perfect for stock rebuilds or high-performance race applications.

Lightweight 7-degree billet steel retainers designed to match conical spring shape, stronger than OEM.

Includes 7-degree valve locks designed for these retainers.

Heat-treated spring shims available in various thicknesses for adjusting seat pressure to accommodate max boost.