Page 6 - Catalog spare parts NGK for cars

Auto Parts / Symbols used on spark plugs

The standard symbols are shown here. In addition, several special designations are used.

Thread dimensions /
Structur Resistor Heat Rating
Hex. size
A 18mm / 25.4 P Projecting insulator type R Resistor 2 Hot type
B 14mm / 20.8 M Small spark plug Z Inductive resistor type 4
C 10mm / 16.0 U Surface gap,Semi-surface discharge 5
D 12mm / 18.0 gap or Supplementary gap 6
E 8mm / 13.0 7
AB 18mm / 20.8 8
BC 14mm / 16.0 9
BK 14mm / 16.0 10 Cold type
DC 12mm / 16.0

B P R5 ES 11
-

Thread length Design features Spark gap

E 19.0 mm B Integral terminal CR8EB None motorcycle:0.7-0.8 mm car:0.8-0.9 mm
EH 19.0 mm, CM Oblique ground electrode
half-thread Compact type (insulator length:18.5 mm) -8 0.8 mm
H 12.7 mm CS Oblique ground electrode
Compact type (insulator length:18.5 mm) -9 0.9mm
L 11.2 mm G,GV Racing spark plug -10 1.0mm
F Tapered-seat type I Iridium spark plug -11 1.1mm
A-F---10.9 mm IX Iridium IX spark plug -13 1.3mm
B-F---11.2 mm J 2-projecting-electrode -14 1.4mm
B-EF--17.5 mm K 2-ground-electrode -15 1.5mm
BM-F --7.8 mm -L Medium heat rating
None Bantam type -LM Compact type (insulator length:14.5mm)
BM---9.5 mm N Special ground electrode -S Special gasket
BPM--9.5 mm P Platinum spark plug -E Special resistance
CM---9.5 mm Q 4-ground-electrode
S Standard type
T 3-ground-electrode
U Semi-surface discharge gap
VX VX spark plug
Y V-grooved center electrode
Z Special design

GB 4

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