- Honda Car Owner's Manual

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72
SPARKPLUGS
TheInsightusesanew,iridiumsparkplugthatisuniquetothisvehicle.
Therearefourdifferentpartnumbersforthesparkplugs,andeachhastheelectrodealigneddifferently
withtheplugthreads.Thisallowstheorientationofthegroundelectrodeinrelationtotheintakevalveto
beoptimizedformaximumeconomyandpower,andoptimumcombustionefficiency.
Duetovariationsinherenttothemanufacturingprocess,eachengine'sheadwilldiffer.Aftereachhead
ismanufactured,itismeasuredandtheoptimalsparkplugforeachcylinderinthatengineisdetermined.
Thisinformationisthenstampedonthecylinderhead.
Eachsparkplughasanidentificationmark(A,B,CorD)locatedonthetopofthesolidpostterminal
that is to be matched with the corresponding identification mark for each cylinder, as stamped on the
cylinderheadoftheengineinquestion.Thecylinderheadmarkinglocationisshownbelow.
Toensureproperelectrodeposition,onlyreplacesparkplugswithlettercodesthatmatchthestamping
onthecylinderhead.Ifthesparkplugsaretobereused,theymustbereturnedtothesamecylinders.
To ensure proper electrode position, it is also doubly important that the plug is torqued to
specifications.
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