Valve Tappet, Temco Auto Parts

Hydraulic & Mechanical Valve Tappet

The valve tappet, (also called a "follower" or "cam lifter") is the component that makes direct contact with the cam lobes and "follows" the profile of the cam. There are generally four types of lifters:

The hydraulic flat tappet is self-adjusting, due to the valve controlled plunger within the tappet body. It operates to pre-load the push-rod by using the oil system pressure to maintain this pre-load in the closed valve position. Hydraulic tappets are quieter than mechanical tappet lifters since there is no lash or free-play. However, it is generally agreed that they fall short of offering optimum performance above 6,000 - 6,500 RPM. Many cheaper designs fall even shorter than this. This poor performance at high RPM is due mainly to the inability of the lifter to "bleed down" the excessive oil pressure , and thus does not allow the valves to seat.

The mechanical (solid) tappet is essentially a solid "link" between the cam lobe, and the push-rod. In most cases it is a simple heat-treated cylinder with a radiused contact face. It allows more RPM potential than that of the hydraulic tappet since there are no worries about the inability of the lifter to "bleed down." Solid lifters do, however require lash or clearance to allow for part expansion as the engine heats up.

The mechanical (solid) roller tappet allows for the most aggressive lobe designs. Roller tappets allow faster, "steeper" opening and closing ramps. This allows the cam to produce more lift for a given duration. They are not limited to a particular lifter diameter to obtain higher cam lifts. They also contain a roller that reduces friction between cam and followers. Roller cams require the use of higher valve spring forces making high engine speeds (over 10,000 RPM¡¯s) possible.

The hydraulic roller tappet camshaft can provide the best of both worlds. Diesel engines and some motorcycle engines have used this design for many years. They provide most of the virtues of a solid mechanical roller tappet while providing the benefits of quiet operation and ease of valve lash setting.

In modern engines, fast gas exchange between fresh gas and exhaust is absolutely crucial for the emission values. Hydraulic bucket tappets by TEMCO warrant automatic adjustment of the valve lash so that the valves open at the predefined times. This applies across the whole service life of the engine.

TEMCO offer a wide range of valve lifters for passenger cars, vans and light trucks.

* All types of mechanical & hydraulic type tappets available:

* Lifters are precision-machined and heat-treated for strength and durability

* High-quality, chromoly steel, adjustable pushrods are matched to the lifters

* Threaded adjuster allows adjustment of valve lash at the lifter

Products available in OKAYAMA & TOSHIO packing. For more information about TEMCO VALVE TAPPET, please download our catalogues or contact us

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