| 摘要 |
A spark plug comprised of an insulator having a stepped portion on an outer circumferential portion thereof, the stepped portion tapering frontward in the direction of the axis of the spark plug, an annular sheet packing and a metallic shell having a taper portion provided on an inner circumferential portion thereof and tapering frontward in the direction of the axis of the spark plug, the metallic shell holding the insulator through a rear end portion thereof being crimped, the stepped portion being seated on the taper portion via the sheet packing, and the taper portion having a groove therein.
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