SPARK PLUG SELECTION CHART

IF THE ENGINE HEAD WAS RE-WORKED, OR IF A PRECOMBUSTION CHAMBER WAS INSTALLED, VERIFY PLUG SIZE.

ENGINE MODEL UNSHIELDED SHIELDED INTEGRAL COIL TYPE
SEVERE SERVICE NORMAL SERVICE 5/8″-24 SHIELD 3/4″-20 SHIELD 13/16″-20 THREAD 1″-20 THREAD
MEP/Fairbanks Morse
MEP-6, 8, 10, 12 RB485-1 RB485-1 RBH485SD SEE NOTE 1 SEE NOTE 2
38FS5-1/4 BG341-1 SEE NOTE 1 SEE NOTE 2
NORDBERG
4FG, FSE 96 Natural Gas BG341-1 SEE NOTE 1 SEE NOTE 2
WAUKESHA
AT25GL, AT27GL RB485-1 RB485-1 RBH485SD SEE NOTE 1 SEE NOTE 2
FC, 180GKB, 190GLB, 195GK RB485-1 RB485-1 RBH485SD SEE NOTE 1 SEE NOTE 2
F1197G, F1197GR, F1197GRSI RB485-1 RB485-1 RBH485SD SEE NOTE 1 SEE NOTE 2
F1905GR, F1905GRSI, H2BG5G, L3711G RB485-1 RB485-1 RBH485SD SEE NOTE 1 SEE NOTE 2
H1077G, H1077GSI (18mm Heads) RB485-1 RB485-1 RBH485SD SEE NOTE 1 SEE NOTE 2
L1616G, L1616GSI (18mm Heads) RB485-1 RB485-1 RBH485SD SEE NOTE 1 SEE NOTE 2
F2895G, F2895GSI, F3521G, F3521GSI RB485-1 RB485-1 RBH485SD SEE NOTE 1 SEE NOTE 2
L5108G, L5108GSI, L5790G, L5790GSI RB485-1 RB485-1 RBH485SD SEE NOTE 1 SEE NOTE 2
L7042G, L7042GSI RB485-1 RB485-1 RBH485SD SEE NOTE 1 SEE NOTE 2
P9390G. P9390GSI RB485-1 RB485-1 RBH485SD SEE NOTE 1 SEE NOTE 2
180GL, 190GL, 195GL RB485-1 RB485-1 RBH485SD SEE NOTE 1 SEE NOTE 2
140GK, 140GZ, 185GL, 145GKB (18mm Heads) RB485-1 RB485-1 RBH485SD SEE NOTE 1 SEE NOTE 2
WAK, WAKB, WAKC, NK, NKR RB485-1 RB485-1 RBH485SD SEE NOTE 1 SEE NOTE 2
LRO, LROR (7/8″ -18 Heads) RB212-1 RB212-1 RB312S-1 RB118SD SEE NOTE 1 SEE NOTE 2
LRO, VLRO, LRZ (18mm Heads) RB485-1 RB485-1 RBH485SD SEE NOTE 1 SEE NOTE 2
F2894G, F2894GR, F2894GRSI RB485-1 RB485-1 RBH485SD SEE NOTE 1 SEE NOTE 2
F3520G, L7040G RB485-1 RB485-1 RBH485SD SEE NOTE 1 SEE NOTE 2
L5100GR, LT100GRSI, L5788GR, L5788GRSI RB485-1 RB485-1 RBH485SD SEE NOTE 1 SEE NOTE 2
BA, BL, BM, BK, BZ, CHK, CHS, CR, CSR RB485-1 RB485-1 RBH485SD SEE NOTE 1 SEE NOTE 2
CU, DHK, DK, DKR, DR, DU, EK, EL RB485-1 RB485-1 RBH485SD SEE NOTE 1 SEE NOTE 2
FCL, FCS, FL, FLS, FS, GAK RB485-1 RB485-1 RBH485SD SEE NOTE 1 SEE NOTE 2
130GS, 130GL, 140GZ, 180G RB485-1 RB485-1 RBH485SD SEE NOTE 1 SEE NOTE 2
MK, ML, MS, MZA, SRK, RBR RB485-1 RB485-1 RBH485SD SEE NOTE 1 SEE NOTE 2
MZ, MRK, MZR, SRKR RB212-1 RB212-1 RB312S-1 RB118SD SEE NOTE 1 SEE NOTE 2
SPLR, WOK, VIK, XAH RB212-1 RB212-1 RB312S-1 RB118SD SEE NOTE 1 SEE NOTE 2
7044 GSI ————————— CALL FACTORY ————————
GL and GLD Series ————————— CALL FACTORY ————————
SUPERIOR
1979-80 6GTL, 8GTL, 12GTL, 16GTL RB485-1 RB485-1 RBH485SD SEE NOTE 1 SEE NOTE 2
1976-80 12SGT, 16SGT RB485-1 RB485-1 RBH485SD SEE NOTE 1 SEE NOTE 2
1970-80 12G825, 16G825 RB485-1 RB485-1 RBH485SD SEE NOTE 1 SEE NOTE 2
6GT510, 8G825, 6G825, 6G510 RB485-1 RB485-1 RBH485SD SEE NOTE 1 SEE NOTE 2
12GT825, 16GT825, 6GT825 RB485-1 RB485-1 RBH485SD SEE NOTE 1 SEE NOTE 2
8GT825, 6GX825, 8GX825 RB485-1 RB485-1 RBH485SD SEE NOTE 1 SEE NOTE 2
12VG825, 12VGT825, 16VG825, 16VGT825 RB105-1 RB212-1 RB312S-1 RB118SD SEE NOTE 1 SEE NOTE 2
SGTB Clean Burn RB485-1 RB485-1 RBH485SD SEE NOTE 1 SEE NOTE 2
2406G, 2408G, 2412G, 2416G RB485-1 RB485-1 RBH485SD SEE NOTE 1 SEE NOTE 2
WORTHINGTON
AG, BG, BBG, EEGX, LCE, SDHG RB212-1 RB312S-1 RB118SD SEE NOTE 1 SEE NOTE 2
GG, CCG, CCGX, DG, DDG, EEG, LFC RB212-1 RB312S-1 RB118SD SEE NOTE 1 SEE NOTE 2
LTC, 18X25, 20X25 Horizontal 4 Cycle RB105-1 RB105-1 RB118SD SEE NOTE 1 SEE NOTE 2
ML, UTC, SLHC, SLHCA, SLHP RB105-1 RB105-1 RB118SD SEE NOTE 1 SEE NOTE 2
SUTC, SEH, SDHG, SDHP RB105-1 RB105-1 RB118SD SEE NOTE 1 SEE NOTE 2

NOTE 1: Use the 3/4″ -20 Shielded Plug with the “FM1” Series Coil Adapters (Page 26) or
              Use the 5/8″ -24 Shielded Plug with the “FME” Series Coil Adapters (Page 26)

NOTE 2: Use the 3/4″ -20 Shielded Plug with the “M” Series Coil Adapters (Page 27) or
              Use the 5/8″ -24 Shielded Plug with the “E” Series Coil Adapters (call factory)


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