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)