An extension-type spark plug (10) is disclosed for igniting the air-fuel mixture in an internal combustion engine. The spark plug (10) includes an installation conduit (12), a contact button (34), an electrode extension (20), a firing electrode (60), a ground plate (66), a sleeve insulator (22), an upper insulator (90) and a lower insulator (50). The electrode extension (20) is axially aligned with and in communication with the firing electrode (60). The ground plate (66) is proximate the firing electrode (60) to define a spark gap between the firing electrode (60) and a first end of the ground plate (66). The sleeve insulator (22) surrounds the electrode extension (20). The upper insulator (90) surrounds an upper portion of the electrode extension (20) and is in contact with the sleeve insulator (22). The lower insulator (50) surrounds the lower portion of the electrode extension (20) and is in contact with the sleeve insulator (22).