Cummins for the 1998.5 to 2016 Dodge Cummins Turbo Diesel. These OEM Cummins tappets are for use on the Cummins 5.9L and 6.7L Turbo Diesel engines. This Cummins 3947759 Tappet is the Original Equipment Manufacturer part. This OEM Tappet is the same tappet that was made and installed by Cummins at the factory.
These OEM Cummins Common-rail Tappets are a complete set of twelve tappets for a Cummins 5.9L or Cummins 6.7L 24 Valve Diesel engine.
These Cummins 3947759 Lifters, Tappets are a recommended replacement when installing a High Performance Camshaft in your Cummins Turbo Diesel engine. Installation of these new Cummins 3947759 5.9L and 6.7L Tappets are for high horsepower and High RPM engine builds or modifications. These Cummins tappets have a larger cam footprint than the stock 12 and 24 Valve Cummins Tappet. The more substantial contact of the Cummins tappet is used to ensure constant contact with a modified camshaft profile as the engine revolutions are increased. RPM's is increased. Using old tappets on a new camshaft could cause uneven wear on the camshaft itself. These Cummins tappets sold as a complete set of 12 tappets required for your modification.
The term tappet is widely used with internal combustion engines. It is most commonly encountered as a maintenance task for overhead valve engines, that of 'adjusting the tappets'. This operation improves the overall clearance in the valve actuation system: typically 20 thousandths of an inch (0.5 mm). The name arises because it is the clearance of the tappets that is adjusted, even though the adjustment is not made to the tappets themselves.
Strictly speaking, the tappet is that part also termed a cam follower that runs on the camshaft and is made to move vertically by the action of the rotating cam. In an overhead valve engine, this tappet is fitted down in the engine block. From there it drives a long thin pushrod, up to the top of the engine, above the cylinder head. Here the rockers, arranged on a rocker shaft beneath the rocker cover, reverse the direction of the valve movement to press the valves downwards to open them.