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Tightening torques for spark plugs

Torques force which is applied to the If the tightening torque is set too
A torque wrench is required for respective centre of rotation and high, the spark plug can snap off.
the professional installation of a the length of the handle. The casing can also expand or
spark plug. Even for professionals Most spark plug failures can be warp. Heat dissipation zones are
the estimation of the tightening traced back to an incorrect disrupted, overheating and
torque is nearly impossible. tightening torque. If it is set too melting of the electrodes or even
low, there is a risk of compression engine damage can occur.
That is because a torque can be losses and overheating. A break
calculated from two sizes which of the insulator or middle electrode
are multiplied by one another: the feasible.

Spark plug with flat seat Spark plug with
(with gasket) conical seat

Cylinder head Thread diameter Thread diameter
material
18 mm 14 mm 12 mm 10 mm 18 mm 14 mm
Cast iron head 35-45 Nm 10-15 Nm
35-40 Nm 25-35 Nm 15-25 Nm 10-12 Nm 20-30 Nm 15-25 Nm
Aluminium head
25-30 Nm 15-20 Nm 20-30 Nm 10-20 Nm

The torques depend on the cylinder head material and the thread diameter.

GB X