THE WORLD'S FAVORITE SPARK PLUG.™

TECHNICAL INFORMATION■ Factors Affecting Voltage Requirements (Vr) continued ■LOWVOLTAGELOW COMPRESSION PRESSURE HIGH HIADVANCE AWAY FROM TDC IGNITION TIMING RETARD TOWARDSTDCGLOW SPEED AND LOAD HIGHHHOT ELECTRODE TEMPERATURE COLDWELL DEFINED ELECTRODE CONDITION WORN VNICKEL ELECTRODE MATERIAL PLATINUM OLNARROW GAP SIZE WIDETNEGATIVE COIL POLARITY POSITIVEASTOICHIOMETRIC FUEL/AIR RATIO LEAN GLOW TURBOCHARGING HIGH EFIGURE 4■ Factors Affecting Spark Plug Temperatures ■SPEED AND LOADAs engine power requirements increase with speed and load,spark plug insulator temperatures increase proportionately. Temperaturesat constant speed and load will remain relatively stable.IGNITION TIMINGIgnition timing has one of the greatest effects on insulatortemperature. Advances in timing subjects the insulator as well asall other parts of the combustion chamber to longer periods offlame exposure. Recommended spark plug heat ranges,therefore, must consider manufacturers' specified timing andfuel/air ratios. Any advances over specifications will increaseinsulator temperatures.CYLINDER HEAD TEMPERATURESInsulator temperatures will vary almost directly with cylinderhead temperatures. A fifty degree increase in coolanttemperature will increase the insulator approximately fiftydegrees–a negligible amount. In cases of localized cooling systemblockages (liquid or air), it is possible to create severeoverheating. Extremes in ambient operating temperatures can bedetrimental to cylinder heat temperatures by creating adetonation or pre-ignition environment.DETONATIONDetonation produces severe pressures and temperatures whichmay affect not only spark plug temperatures but also mayimpose severe stress on insulators, electrodes, pistons, valves,bearings and other engine components.PRE-IGNITIONPre-ignition will generally cause a very rapid and severetemperature rise in the spark plugs and other combustionchamber components.INSTALLATION TORQUEOver-torquing or under-torquing upon installation can impair heattransfer out of the spark plug, causing the spark plug to leak andrun hotter, decreasing its life.COLDLOW ENGINE SPEED HIGHLOW ENGINE LOAD HIGHRETARDED IGNITION TIMING ADVANCEDLOW CYLINDER HEAD & COOLANT TEMPERATURE HIGHNONE DETONATION SEVERENONE PRE-IGNITION SEVERECORRECT TORQUE INSTALLATION TORQUE OVER/UNDER-TORQUEHOTFIGURE 526