Clearance very affect the performance of spark plug, so different models must use the manufacturer recommended clearance value, not too large or small. Each brand of spark plug has a model number, usually at the end of the number or letter to represent the gap value.
Bosch — At the end of the model, S, T, U, V, W, X, Y, Z is used to represent 0.7mm, 0.8mm, 1.0mm, 1.3mm, 0.9mm, 1.1mm, 1.5mm, 2.0mm in turn. Generally, T (0.8mm) is directly omitted and not marked. In fact, many models do not indicate the gap value.
NGK — At the end of the model or where the second number appears, 6, 7, 8, 9, 10, 11, 13, 15 are used to represent 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1.0mm, 1.1mm, 1.3mm, 1.5mm, generally 8 (0.8mm) is omitted directly.
Electrical equipment — At the end of the model or where the second number appears, 6, 7, 8, 9, 10, 11, 13, 15 are used to represent 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1.0mm, 1.1mm, 1.3mm, 1.5mm in turn, generally 8 (0.8mm) is directly omitted. Iridium models do not indicate clearance values.
Torch — At the end of the model or where the second number appears, use 6, 7, 8, 9, 10, 11, 13, 15 to indicate 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1.0mm, 1.1mm, 1.3mm, 1.5mm in turn, generally 8 (0.8mm) is directly omitted.
Polar combustion — Polar combustion is a double-clearance spark plug, corresponding to the conversion of traditional clearance values, 330, 440, 550, 770 at the end of the model, indicating that the second clearance is 0.3mm, 0.4mm, 0.5mm, 0.7mm.
