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A valve job is the colloquial term for resurfacing the mating surfaces of the poppet valves and their respective valve seats that control the intake and exhaust of the air/fuel mixture in four stroke internal combustion engine, replacing valve oil seals, replacing any deficient valve springs, and otherwise bringing the components of a cylinder head up to manufacturer’s spec. [1] A ...
With traditional fixed valve timing, an engine will have a period of "valve overlap" at the end of the exhaust stroke, when both the intake and exhaust valves are open. The intake valve is opened before the exhaust gases have completely left the cylinder, and their considerable velocity assists in drawing in the fresh charge.
A "top overhaul" is composed of the replacement of components inside the cylinder head without removing the engine from the vehicle, such as valve and rocker arm replacement. It may include a "valve job". A "major overhaul" is composed of the whole engine assembly, which requires the engine to be removed from the vehicle and transferred to an ...
Valve seats are often formed by first press-fitting an approximately cylindrical piece of a hardened metal alloy, such as Stellite, into a cast depression in a cylinder head above each eventual valve stem position, [1] and then machining a conical-section surface into the valve seat that will mate with a corresponding conical section of the ...
The word poppet shares etymology with "puppet": it is from the Middle English popet ("youth" or "doll"), from Middle French poupette, which is a diminutive of poupée.The use of the word poppet to describe a valve comes from the same word applied to marionettes, which, like the poppet valve, move bodily in response to remote motion transmitted linearly.
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Valve – a device or natural object (such as a heart valve) that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways; Vector – a geometric object that has magnitude (or length) and direction.
In fact, with a line-commutated converter, the firing angle represents the only fast way of controlling the converter. Firing angle control is used to regulate the DC voltages of both ends of the HVDC system continuously in order to obtain the desired level of power transfer. Valve voltage and current for inverter operation with γ=20° and μ=20°