Multi-colored deposits on the insulator and electrodes indicate the presence of a large amount of additives in the fuel or engine oil. Black, matte soot on the insulator, electrodes and body is a sign of operation in most modes on an over-enriched mixture or too high heat number. Carburetor or injection system adjustments need to be checked (e.g. gas analyzer) or install a hotter spark plug. Shiny black soot indicates that lubricant has entered the cylinder through the piston rings and valve guides. Engine repair required.
If the insulator "snow white" coloring - it means that the candle worked at the maximum allowable thermal regime. Causes: too early ignition, too lean mixture or too "hot" spark plug for this engine. It is necessary to check the carburetor settings, the characteristics of the ignition timing device and, if they are normal, set more" cold" candle. Well, the next degree of overheating of the candle is the melted electrodes of the candle (it’s good that the piston bottom has not burned out).
Sometimes it may turn out that all candles of the same brand in different cylinders have insulators of different colors. There may be several reasons. As a rule, in carbureted engines, the mixture (composition) and anti-knock additives are unevenly distributed over the cylinders.
There are engines with different compression ratios for each of the cylinders. Well, between engines of the same model, the compression ratio sometimes differs by a whole unit. Due to the deviation from technological processes, materials, etc., among candles of the same brand, there is also a large spread in actual glow numbers. With a large difference in the condition of the candles, it is sometimes necessary to install candles with different glow numbers even in the same engine. In order to always have a reserve for the glow number in various operating conditions, it is advisable to have two sets of candles and install more in the summer "cold", and in winter "hot".
Recently, a number of companies have been producing candles with an extended thermal field of the candle. To do this, the central electrode is made of copper, a coating of heat-resistant materials is applied on top (nickel, chrome). Sometimes the side electrodes are made of metal with good thermal conductivity and a heat-resistant coating. Another original solution is to make a miniature platinum central electrode that does not protrude from the insulator. especially "cold" spark plugs with a glow number of 300 and higher for uprated engines (turbocharged, two-stroke, etc.) usually made with a small diameter silver electrode and a short insulator skirt. Before installing such candles, it is sometimes recommended to first warm up the engine on hot candles and only then install cold ones.
It must be borne in mind that when cleaning the candle in a sandblaster, the surface of the insulator is destroyed. It is better to turn the candle over and pour solvent, gasoline into the body or use a special aerosol can. Then clean the insulator with a wooden stick and blow it with compressed air.
Visitor comments