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ISO vs. JIS Spark Plug Heights

ISO (International Standards Organization) is an international organization which establishes standards for the production of automobiles and their parts. The ISO height for a spark plug from the seat to the top of the terminal nut is 50.5mm (1.98").

JIS (Japanese Industrial Standards) is a Japanese organization which establishes standards for the production of Japanese automobiles and their parts. The JIS height for a spark plug from the seat to the top of the terminal nut is 53mm (2.086").

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ISO Plug HeightJIS Plug Height