Page 8 - NGK-sytytystulpat-klassikkoautoihin

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

B P R 5 E S - 11

Thread length Design features Spark gap
None motorcycle:0.7-0.8 mm car:0.8-0.9 mm
E 19.0 mm B Integral terminal CR8EB
EH 19.0 mm, CM Oblique ground electrode -8 0.8 mm

half-thread Compact type (insulator length:18.5 mm) -9 0.9mm
H 12.7 mm CS Oblique ground electrode -10 1.0mm
-11 1.1mm
L 11.2 mm Compact type (insulator length:18.5 mm) -13 1.3mm
F Tapered-seat type G,GV Racing spark plug -14 1.4mm
I Iridium spark plug -15 1.5mm
A-F---10.9 mm IX Iridium IX spark plug
B-F---11.2 mm J 2-projecting-electrode -S Special gasket
B-EF--17.5 mm K 2-ground-electrode -E Special resistance
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
BPM--9.5 mm P Platinum spark plug
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 VI