Ignition timing Ignition timing In a spark ignition internal combustion engine, Ignition timing refers to 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. The need for advancing (or retarding) the timing of the spark is because fuel does not completely burn the instant the spark fires, the combustion gases take a period of time to expand and the angular or rotational speed of the engine can lengthen or shorten the time frame in which the burning and expansion should occur. In a
Period 3 element as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks. Elemental phosphorus exists in two major forms—white phosphorus and red phosphorus—but due to its high reactivity, phosphorus is never found as a free element on Earth. The first form of elemental phosphorus to be produced (white phosphorus, in 1669) emits a faint glow upon exposure to oxygen – hence its name given from Greek mythology, meaning "light-bearer" (Latin "Lucifer"), referring to the "Morning Star", the planet Venus. Although the term "phosphorescence", meaning glow after illumination, derives from this property of phosphorus, the glow of