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In spark-ignition internal combustion engines, knocking (also knock, detonation, spark knock, pinging or pinking) occurs when combustion of some of the air/fuel mixture in the cylinder does not result from propagation of the flame front ignited by the spark plug, but when one or more pockets of air/fuel mixture explode outside the envelope of the normal combustion front.
Pressure in cylinder pattern in dependence on ignition timing: (a) - misfire, (b) too soon, (c) optimal, (d) too late. In a spark ignition internal combustion engine, ignition timing is the timing, relative to the current piston position and crankshaft angle, of the release of a spark in the combustion chamber near the end of the compression stroke.
As the whole process is actuated by hydraulic pressure at engine start, there is no need for service or adjustment. Another advantage is cheaper operation, as there is no need for service and charges associated with tappet maintenance. Usually hydraulic tappets survive through the whole of the engine life without any service requirements.
Loose set screws can cause catastrophic engine failure, which has led to fatal aircraft crashes. [9] On some OHV engines in the 1960s, such as the Ford Taunus V4 engine and Opel CIH engine, the tappet adjustment was done by setting the height of the rocker pivot point (rather than the typical method of a rocker-end adjustment screw). On the ...
The reduced engine speeds allow more time for autoignition chemistry to complete thus promoting the possibility of pre-ignition and so called "mega-knock". Under these circumstances, there is still significant debate as to the sources of the pre-ignition event. [3] Pre-ignition and engine knock both sharply increase combustion chamber temperatures.
Also gas pedal. A throttle in the form of a foot-operated pedal, or sometimes a hand-operated lever or paddle, by which the flow of fuel to the engine (and thereby the engine speed) is controlled, with depression of the pedal causing the vehicle to accelerate. admission stroke See induction stroke. aftermarket air brake 1. A type of brake in which the force that actuates the brake mechanism is ...
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A desmodromic valve is a reciprocating engine poppet valve that is positively closed by a cam and leverage system, rather than by a more conventional spring. The valves in a typical four-stroke engine allow the air/fuel mixture into the cylinder at the beginning of the cycle and exhaust spent gases at the end of the cycle. In a conventional ...