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Surface Discharge Spark Plug

Bulletin 1017

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Marine and highly modified engine applications


This bulletin will explain the gap area and how the spark travels on a surface discharge spark plug


Technical service receives many questions on how a surface discharge spark plug fires and if the gap is variable. Surface discharge spark plugs have no ground electrode and therefore are not adjustable. This type of spark plug is designed to have a set value from the spark plug center electrode to outer shell. The primary use for a spark plugs like this would be extreme compression engines and many marine applications. In modified high compression engines with power adders such as nitrous, supercharged and turbocharged applications this type of spark plug can offer increased clearance between the piston and spark plug as well as exceptional durability.


When choosing this type of spark plug you will find them on the extremely cold side of the heat range scale. Due to their design they can dissipate a large amount of heat in a rather short amount of time while keeping the center electrode of the spark plug at the correct temperature for efficient combustion and self-cleaning.


A surface discharge spark plug fires the spark sideways from the center electrode to the outside shell. The spark will use the path of least resistance on the 360-degree surface allowing the spark plug to continue firing under adverse conditions found in a performance application while also in carbon foul conditions.


For addition support contact the GoTech technical services team at 855-207-5630 M-F 7:30-6:00 CST for assistance.

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