24 Valve Cummins Turbo Diesel

Improvements and design changes that set it apart from the 12 Valve series
Page 3 - Cylinder Head And Valve Train

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CYLINDER HEAD AND VALVE TRAIN

• A one piece cylinder head (valve) cover (Fig 9) replaces the six individual covers previously used. The reusable one-piece gasket (Fig 10) is easier to service, and the gasket is noise-isolated to reduce engine noise. The gasket and cover are not interchangeable with the set used on 12 valve engines.

• All cylinder head bolts are the same length instead of the 3 different lengths used earlier. The uniform bolts make service easier and provide more uniform head clamping.
• The cylinder head gasket is a new design and configuration that improves combustion sealing.
• The exhaust ports (Fig 11) are reshaped to improve combustion efficiency.

• The cylinder head now uses two intake and two exhaust valves per cylinder (Fig 12) - hence the 24 valve designation commonly used.  These valves are smaller than the valves used in 12 valve engines.  The new valves can be identified by the dimple in the center of the valve face (Fig 13).

• A new rocker arm design allows removal of fuel injectors without disturbing valve lash. The crosshead (Fig 14) enables one rocker arm to actuate two valves at the same time. The crosshead socket acts as a pivot to allow the crosshead to operate the valves.

• Wider camshaft lobes and tappet faces as well as longer pushrods reduce valvetrain wear and stress.  The fuel lift pump is electric and the camshaft has no fuel pump lobe.
• A camshaft position sensor, which senses when cylinder no. 1 is a TDC, is mounted in the the former TDC pin location (Fig 15). There is also a TDC indication stamped on the outside of the gear housing cover

• A new thermostat is vertically mounted in a housing that is integral to the 24 valve cylinder head.