PLUG STUDIO / NGK

Is there a specified tightening torque for the spark plug?

The tightening torque for a spark plug changes with the diameter of the spark plug.
The following are the recommended torque values.

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When installing the spark plug, first screw it in by hand. Once the gasket has made contact with the cylinder head, use the torque wrench to tighten it to the tightening torque shown below.

A rubber pipe as shown in the figure to the right is a good substitute for hand tightening/removing spark plugs.

Tightening torque

Plug thread diameter	Tightening torque
18 mm	35 to 40N·m (3.5 to 4.0 kgm)
14 mm	25 to 30N·m (2.5 to 3.0 kgm)
12 mm	15 to 20N·m (1.5 to 2.0 kgm)
10 mm	10 to 12N·m (1.0 to 1.2 kgm)
8 mm	8 to 10N·m (0.8 to 1.0 kgm)

Tapered seat type For (spark plugs without gaskets)

Tightening torque
10 to 20 N·m (1.0 to 2.0 kg-m)

The tightening angle for both new and reused spark plugs is 1/16th of a turn.

For reference

When it is difficult to use a torque wrench, or when you don't have a torque wrench, tighten the spark plug to the tightening angle shown in the illustration in accordance with the thread diameter of the spark plug.

Spark plugs with thread diameter of 18 and 14 mm

Spark plugs with thread diameter of 12 and 10 mm

Spark plugs with thread diameter of 8 mm

Taper seat type

New plugs	Reused
About 1/16 rotations (22.5°)	About 1/16 rotations (22.5°)

Copper gasket type

New plugs	Reused
About 1/12 rotations (30°)	About 1/24 rotations (15°)

[ attention ] Please note that the turning angle of a past plug and tightening is different about the following product number.

♦

BCPR6ED	BKR5EKUC	BKR6EKE	IZFR5C
BCPR6EKD	BKR5EKUD	BKR5ETUA	PZFR5C
BCPR7EKD	BKR6EKUC	HB6AIX-11P	R6469-9
BCPR7EDIX	BKR6EKUD	HB6BIX-11P	R6918C-9

New Plugs About 1/3 rotations
Reused About 1/12 rotations

♣

DILZKR7A11GS	ILZKR7B11GS	ILZKR7B-11S
SILKR8A-S	R2556B-*	R2558A-*

New Plugs About 1/4 rotations
Reused About 1/8 rotations

♠

CPR6EA-9S	CR8EH-9S	CR9EH-9S	IMR8C-9HES
IMR9C-9HES	IMR9D-9H	IMR9E-9HES	SILMAR9A9S
SILMAR10A9S	SILR6A7S	SILR7A7S	SPMR8A6HDG
R0409B-*	R0451B-8

New Plugs About 1/6 rotations
Reused About 1/12 rotations

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

* There are some exceptions. Look at the adaptation for more information.

Examples of common installation problems and advise to avoid them.

Thread damage from installation	Metal shell damage	Cracked insulator	Examples of bad spark plug wrench usage

Spark plug is inserted at an angle during installation	Excessive tightening torque	Spark plug wrench slipped or used at an angle
Do not use the wrench at first. Start by installing the spark plug by hand.	Tighten to recommended torque.	Use a hex-type wrench that is less likely to slip.

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