Thread: Numbers on C-4 spark plugs
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Old 11-16-2020, 08:16 PM   #1
1crosscut
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Join Date: Feb 2011
Location: Lincoln, Nebraska
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Default Numbers on C-4 spark plugs
I've started working on cleaning up some C-4 spark plugs. After taking several of them apart I've noticed that there are numbers towards the bases of the porcelain that are hidden when they are assembled. Most have a number but some do not.
Any idea as to what the numbers represent?
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File Type: jpg Spark plug numbers.jpg (92.7 KB, 113 views)
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