PLUG STUDIO / NGK

The tightening torque for spark plugs varies depending on the thread diameter of the plug. If a plug is tightened with a torque exceeding the recommended torque, the thread could break. See Photo 1.		Photo 1:
1)	Apart from overtightening, another possible cause of a thread break in a plug is the application of an anti-seizure agent or oil when fitting the plug, since this lowers the friction resistance and means that the thread can be turned more than necessary. Never use an anti-seizure agent or oil.
2)	When fitting a spark plug, use a torque wrench and tighten it with the recommended torque. For situations where it is not possible to use the list of recommended torques and a torque wrench, the turning angles to achieve correct tightening are also given below.

	Tightening torque
Taper seat type (plug with no gasket)	10 - 20N · m(1.0 - 2.0kgf-m)

Plug thread diameter	New plugs	Reused
18,14mm( ♦ is excluded. )	About 1/2 - 2/3 rotations (180° - 240°)	About 1/12 rotations (30°)
♦ BCPR6ED BCPR7EKD BKR5EKUC BKR6EKUC BKR6EKE HB6AIX-11P IZFR5C R6469-9 BCPR6EKD BCPR7EDIX BKR5EKUD BKR6EKUD BKR5ETUA HB6BIX-11P PZFR5C R6918C-9	About 1/3 rotations (120°)	About 1/12 rotations (30°)
12mm( ♣ is excluded. )	About 1/2 rotations (180°)	About 1/12 rotations (30°)
♣ DILZKR7A11GS ILZKR7B-11S R2556B-* ILZKR7B11GS SILKR8A-S R2558A-*	About 1/4 rotations (90°)	About 1/8 rotations (45°)
10mm( ♠ is excluded. )	About 1/2 rotations (180°)	About 1/12 rotations (30°)
♠ CPR6EA-9S CR9EH-9S IMR9C-9HES IMR9E-9HES SILMAR10A9S SILR7A7S R0409B-* CR8EH-9S IMR8C-9HES IMR9D-9H SILMAR9A9S SILR6A7S SPMR8A6HDG R0451B-8	About 1/6 rotations (60°)	About 1/12 rotations (30°)
8mm	About 1/3 rotations (120°)	About 1/12 rotations (30°)
Taper seat type (plug with no gasket)	About 1/16 rotations (22.5°)	About 1/16 rotations (22.5°)
Copper gasket type	About 1/12 rotations (30°)	About 1/24 rotations (15°)

The heat value enters for * of the end of R2556B-*, R2558A-*, and R0409B-*.