Valvetrain

The valvetrain opens and closes the intake and exhaust valves, and it has to stay in time with the engine at every RPM. On a diesel running more boost or RPM, factory valve springs and pushrods are common weak points: weak springs let the valves float, and bent pushrods cause misfires and, in the worst case, engine damage.

Shop pushrods sorted by diameter and length, valve springs, retainers and locks, rocker arms, bridges and lifters, and valves, seals and guides. Most of this collection comes from Manley, along with parts from Hamilton Cams, Industrial Injection, COMP Cams, Fleece, PPE and ARP.

Upgraded valve springs are recommended for most Cummins builds running higher boost or a larger turbo, and they are required with most aftermarket camshafts. When choosing pushrods, measure for the correct length rather than guessing, especially if the head or block has been machined. New valve seals are cheap insurance any time the springs come off.