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A hydraulic tappet, also known as a hydraulic valve lifter or hydraulic lash adjuster, is a device for maintaining zero valve clearance in an internal combustion engine. Conventional solid valve lifters require regular adjusting to maintain a small clearance between the valve and its rocker or cam follower. This space prevents the parts from ...
To a degree, some of these maladies were dealt with during the Zephyr's first year, and Ford improved the engine by adopting hydraulic valve lifters for 1938 and cast-iron heads and oiling improvements for 1942. Yet this V-12 never shed its reputation for service troubles, though the postwar versions were actually quite reliable.
In an internal combustion engine, a tappet (also called a 'valve lifter' or 'cam follower') [3] [4] [5] is the component which converts the rotation of the camshaft into vertical motion to open and close an intake or exhaust valve. The principal types of tappets used in automotive engines are solid, hydraulic, and roller. [6] [7]
Since the 1960s, Italian motorcycle manufacturer Ducati has used a desmodromic valvetrain to counter this problem and allow for higher engine speeds by using positive closing as well as opening of the valves, without springs. The system consists of a mechanical lifter mechanism that uses a second rocker arm to push the valve closed.
For model year 1981, all North American G-engines received top-fed hydraulic lifters. Retrofitment in both directions is possible. Emission control devices and systems, carburetor make and specification, and engine assembly details changed over the years to comply with market requirements and preferences.
A solenoid control valve assembly integrated into the engine valley cover contains solenoid valves that provide a pressurized oil signal to specially designed hydraulic roller lifters provided by Eaton Corp. and Delphi. These lifters disable and re-enable exhaust and intake valve operation to deactivate and reactivate engine cylinders . Unlike ...
Since those days, lift, velocity, acceleration, and jerk curves for cams have been modelled by computer [6] to reveal that cam dynamics are not what they seemed. With proper analysis, problems relating to valve adjustment, hydraulic tappets, push rods, rocker arms, and above all, valve float, became things of the past without desmodromic drive.
The CVH features hydraulic valve lifters, a first for a European Ford engine. In North America the engine was sold under different names, being called the "1.9L SEFI" from 1991 to 1996 in that market's Ford Escort, the "Split Port Induction 2000" or SPI2000 from 1997 to 2002, while from 2000 to 2004 it was simply the "Split Port" when offered ...