Posted January 20, 201114 yr comment_342740 Here are the NGK spark plug guides for us. Using the chart attached below, we see that the NGK BPR6ES spark plug (for example) refers to: B - 14mm Thread Size and 13/16" Hex Size P - Projected Tip R - Resistor Type 6 - Heat Rating (2 = hot, 12 = cold) E - 19mm Thread Reach S - Standard 2.5mm center electrode Link to comment https://www.classiczcars.com/forums/topic/38310-ngk-spark-plugs-chartsguide/ Share on other sites More sharing options...
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