Tightening torque

Check condition and cleanliness of threads in cylinder head

Ensure plug is gapped according to vehicle manufacturers specification (fig 1)

Multi ground electrode and precious metal plugs should not be regapped – visual inspection only

Install new spark plug by hand until it seats – (fig 2) a length of rubber tubing pushed over the insulator can be a useful aid for plug installation where access is difficult

Tighten to specified torque setting as shown in the chart below (fig 3)

If a torque wrench is unavailable then refer to vehicle /engine manufacturers installation instructions or the tightening angle advice which is displayed on current NGK packaging (excluding specialist race plugs). Note that this angle advice can differ between part numbers due to individual spark plug design (e.g. seating type, thread diameter and gasket material)

It is important not to over or under tighten spark plugs during installation. Overtightening
can lead to distortion of the spark plug. Under-tightening can cause overheating due to poor heat dissipation. In extreme cases incorrect tightening can cause spark plug breakage and/or engine damage

NGK does not recommend the application of lubricant to spark plug threads as the resultant reduction of frictional forces at the thread faces will render the torque charts inaccurate and over tightening could occur

If a gasket type spark plug is re-installed, it should only require a further 1/12 of a turn after it has been seated

Always carefully use the correct tools for removal/installation to prevent damage to the spark plug or engine

Inspect spark plug cover and renew if necessary

Important: Some spark plugs differ in gasket design or material, refer to tightening advice on specific spark plug packaging