Marine Engine (Inboard)

MERCRUISER STERN DRIVE

110 153L4

Model Year Standard Plug Gap (mm)
MCM GM 4 Cyl., 153 & 181 CID 1963-66 W20ESR-U 0.9

120 (3825578 & Below) 153/L4

Model Year Standard Plug Gap (mm)
MCM GM 4 Cyl., 153 & 181 CID 1964-74 W20ESR-U 0.9

120 (3825579 & Above) 153/L4

Model Year Standard Plug Gap (mm)
MCM GM 4 Cyl., 153 & 181 CID 1974-86 T20R-U 0.9

2.5L 153/L4

Model Year Standard Plug Gap (mm)
MCM GM 4 Cyl., 153 & 181 CID 1987-89 T20R-U 0.9

140 (3826282 & Below) 181/L4

Model Year Standard Plug Gap (mm)
MCM GM 4 Cyl., 153 & 181 CID 1968-74 W20ESR-U 0.9

140 (3826283 & Above) 181/L4

Model Year Standard Plug Gap (mm)
MCM GM 4 Cyl., 153 & 181 CID 1974-86 T20R-U 0.9

3.0L (OD504541 & Below) 181/L4

Model Year Standard Plug Gap (mm)
MCM GM 4 Cyl., 153 & 181 CID 1987-91 T20R-U 0.9

3.0LX with Prestolite ignition 181/L4

Model Year Standard Plug Gap (mm)
MCM GM 4 Cyl., 153 & 181 CID 1990-91 T20R-U 0.9

3.0LX with Delco digital ignition 181/L4

Model Year Standard Plug Gap (mm)
MCM GM 4 Cyl., 153 & 181 CID 1990-91 T20EPR-U 0.9

3.0L (OD504542 & Above) 181/L4

Model Year Standard Plug Gap (mm)
MCM GM 4 Cyl., 153 & 181 CID 1991-04 T20EPR-U 0.9

3.0LX 181/L4

Model Year Standard Plug Gap (mm)
MCM GM 4 Cyl., 153 & 181 CID 1991-97 T20EPR-U 0.9

165 224/L4

Model Year Standard Plug Gap (mm)
MCM Mercury Marine 4 Cyl., 224 cu.in 1987-87 T20PR-U 0.9

170 224/L4

Model Year Standard Plug Gap (mm)
MCM Mercury Marine 4 Cyl., 224 cu.in 1985-86 T20PR-U 0.9

180 224/L4

Model Year Standard Plug Gap (mm)
MCM Mercury Marine 4 Cyl., 224 cu.in 1987-87 T20PR-U 0.9

190 224/L4

Model Year Standard Plug Gap (mm)
MCM Mercury Marine 4 Cyl., 224 cu.in 1985-86 T20PR-U 0.9

3.7L 224/L4

Model Year Standard Plug Gap (mm)
MCM Mercury Marine 4 Cyl., 224 cu.in 1988-89 T20PR-U 0.9

3.7LX 224/L4

Model Year Standard Plug Gap (mm)
MCM Mercury Marine 4 Cyl., 224 cu.in 1988-89 T20PR-U 0.9

470 224/L4

Model Year Standard Plug Gap (mm)
MCM Mercury Marine 4 Cyl., 224 cu.in 1976-84 T20PR-U 0.9

485 224/L4

Model Year Standard Plug Gap (mm)
MCM Mercury Marine 4 Cyl., 224 cu.in 1980-82 T20PR-U 0.9

488 224/L4

Model Year Standard Plug Gap (mm)
MCM Mercury Marine 4 Cyl., 224 cu.in 1983-84 T20PR-U 0.9

140 194/L6

Model Year Standard Plug Gap (mm)
MCM General Motors 6 Cyl,194, 230, 250, 292 CID 1963-63 W20ESR-U 0.9

150 230/L6

Model Year Standard Plug Gap (mm)
MCM General Motors 6 Cyl,194, 230, 250, 292 CID 1964-66 W20ESR-U 0.9

160 250/L6

Model Year Standard Plug Gap (mm)
MCM General Motors 6 Cyl,194, 230, 250, 292 CID 1967-69 W20ESR-U 0.9

165 (2771483 & Below) 250/L6

Model Year Standard Plug Gap (mm)
MCM General Motors 6 Cyl,194, 230, 250, 292 CID 1970-70 W20ESR-U 0.9

165 (2771484 & Above) 250/L6

Model Year Standard Plug Gap (mm)
MCM General Motors 6 Cyl,194, 230, 250, 292 CID 1971-81 T20R-U 0.9

200 292/L6

Model Year Standard Plug Gap (mm)
MCM General Motors 6 Cyl,194, 230, 250, 292 CID 1969-69 W20ESR-U 0.9

185 4 Bbl. 229/V6

Model Year Standard Plug Gap (mm)
MCM General Motors V6, 229 CID 1983-84 T20R-U 0.9

175 262 V6

Model Year Standard Plug Gap (mm)
MCM General Motors V6,262 CID 1987-87 T20R-U 0.9

185 2 Bbl. 262 V6

Model Year Standard Plug Gap (mm)
MCM General Motors V6,262 CID T20R-U 0.9

205 262 V6

Model Year Standard Plug Gap (mm)
MCM General Motors V6,262 CID T20R-U 0.9

262 Mag. TBI Gen+ O803800-OK999999 262 V6

Model Year Standard Plug Gap (mm)
MCM General Motors V6,262 CID 1996-97 T20EPR-U 1.1

4.3L OF802999 & Below 262 V6

Model Year Standard Plug Gap (mm)
MCM General Motors V6,262 CID 1988- 96 T20R-U 1.0

4.3L Gen + (OL010044 & Above) 262V-6

Model Year Standard Plug Gap (mm)
MCM General Motors V6,262 CID 1998-01 T20EPR-U 1.1

4.3L Gen + (OM300000 & Above) 262 V6

Model Year Standard Plug Gap (mm)
MCM General Motors V6,262 CID 2001-04 T16EPR-U 1.1

4.3L EFI Gen+ TBI OL012009-OM299999) 262 V6

Model Year Standard Plug Gap (mm)
MCM General Motors V6,262 CID 1998-01 T20EPR-U 1.1

4.3L MPI (OM300000 & Above) 262 V6

Model Year Standard Plug Gap (mm)
MCM General Motors V6,262 CID 2001-04 IT20 1.5

4.3LH Gen+ OL010044 & Above) 262 V6

Model Year Standard Plug Gap (mm)
MCM General Motors V6,262 CID 1998-01 T20EPR-U 1.1

4.3LX (OF802999 & Below) 262 V6

Model Year Standard Plug Gap (mm)
MCM General Motors V6,262 CID 1988-96 T20R-U 1.0

4.3LX Gen+ (OF803000 - OK999999) 262 V6

Model Year Standard Plug Gap (mm)
MCM General Motors V6,262 CID 1966-67 T20EPR-U 1.1

4.3LXH Gen+(OF803000 - OK999999) 262 V6

Model Year Standard Plug Gap (mm)
MCM General Motors V6,262 CID 1996-97 T20EPR-U 1.1

215 MCM with Mallory ignition 302/V8

Model Year Standard Plug Gap (mm)
MCM Ford V8, 302 CID & 351 CID 1970-72 MA20PR-U 0.7

225 MCM (Ford) 302/-V8

Model Year Standard Plug Gap (mm)
MCM Ford V8, 302 CID & 351 CID 1973-74 MA20PR-U 0.7

888 302/V8

Model Year Standard Plug Gap (mm)
MCM Ford V8, 302 CID & 351 CID 1971-77 MA20PR-U 0.7

190 8cyl 283/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 283 CID, 305 CID,327 CID, 350 CID 1963-64 W16P-U 0.9

200 305/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 283 CID, 305 CID,327 CID, 350 CID 1985-87 T20R-U 0.9

228 305/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 283 CID, 305 CID,327 CID, 350 CID 1977-84 T20R-U 0.9

230 305/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 283 CID, 305 CID,327 CID, 350 CID 1985-87 T20R-U 0.9

5.0L 305/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 283 CID, 305 CID,327 CID, 350 CID 1988-95 T20R-U 0.9

5.0L Gen+ 305/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 283 CID, 305 CID,327 CID, 350 CID 1998-01 T20EPR-U 1.1
MCM General Motors V8, 283 CID, 305 CID,327 CID, 350 CID 2001-04 T16EPR-U 1.1

5.0 EFI Gen+ 305/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 283 CID, 305 CID,327 CID, 350 CID 1998-01 T20EPR-U 1.1

5.0L MPI 305/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 283 CID, 305 CID,327 CID, 350 CID 2001-04 IT20 1.5

5.0LX 305/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 283 CID, 305 CID,327 CID, 350 CID 1998-95 T20R-U 0.9

898 305/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 283 CID, 305 CID,327 CID, 350 CID 1977-84 T20R-U 0.9

250 MCM 327/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 283 CID, 305 CID,327 CID, 350 CID 1968-69 W24S-U 0.0

250 350/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 283 CID, 305 CID,327 CID, 350 CID 1977-77 T20R-U 0.9

255 MCM GM 350/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 283 CID, 305 CID,327 CID, 350 CID 1975-76 T20R-U 0.9

260 350/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 283 CID, 305 CID,327 CID, 350 CID 1978-87 T20R-U 0.9

270 MCM 350/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 283 CID, 305 CID,327 CID, 350 CID 1969-72 W24S-U 0.0

280 TRS 350/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 283 CID, 305 CID,327 CID, 350 CID 1975-76 T20R-U 0.9

300 350/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 283 CID, 305 CID,327 CID, 350 CID 1985-86 T20R-U 0.9

320 EFI 350/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 283 CID, 305 CID,327 CID, 350 CID 1987-89 T20R-U 0.9

350 Mag. Alpha 350/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 283 CID, 305 CID,327 CID, 350 CID 1986-97 T20R-U 0.9

350 Mag. Alpha EFI Gen+ 350/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 283 CID, 305 CID,327 CID, 350 CID 1996-96 T20EPR-U 1.1

350 Mag.Bravo MPI 350/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 283 CID, 305 CID,327 CID, 350 CID 1995-95 T20R-U 0.9

350 Mag.Bravo MPI Gen+ 350/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 283 CID, 305 CID,327 CID, 350 CID 1996-97 T20EPR-U 1.1

350 Mag. MPI Gen+ 350/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 283 CID, 305 CID,327 CID, 350 CID 1998-01 T20EPR-U 1.1

350 Mag. MPI 350/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 283 CID, 305 CID,327 CID, 350 CID 2001-04 IT20 1.5

350 Mag. MPI Horizon 350/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 283 CID, 305 CID,327 CID, 350 CID 2001-04 IT20 1.5

5.7l 350/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 283 CID, 305 CID,327 CID, 350 CID 1988-97 T20R-U 0.9

5.7L Gen+ 350/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 283 CID, 305 CID,327 CID, 350 CID 1998-04 T20EPR-U 1.1

5.7L EFI 350/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 283 CID, 305 CID,327 CID, 350 CID 1995-97 T20R-U 0.9

5.7L EFI Gen+ 350/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 283 CID, 305 CID,327 CID, 350 CID 1998-01 T20EPR-U 1.1

5.7LX 350/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 283 CID, 305 CID,327 CID, 350 CID 1996-97 T20R-U 0.9

5.7LX Bravo EFI Gen+ 350/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 283 CID, 305 CID,327 CID, 350 CID 1996-97 T20EPR-U 1.1

5.7LX EFI 350/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 283 CID, 305 CID,327 CID, 350 CID 1996-97 T20R-U 0.9

233 MCM Ford 351/V8

Model Year Standard Plug Gap (mm)
MCM General Motors 351 CID, 377 CID 1975-77 MA20PR-U 0.7

255 MCM Ford 351/V8

Model Year Standard Plug Gap (mm)
MCM General Motors 351 CID, 377 CID 1973-80 MA20PR-U 0.7

377 Scorpion MCM 377/V8

Model Year Standard Plug Gap (mm)
MCM General Motors 351 CID, 377 CID 1999-00 T20EPR-U 1.1

MX 6.2L MPI (OL680003-OM299999) 377/V8

Model Year Standard Plug Gap (mm)
MCM General Motors 351 CID, 377 CID 2000-01 T16EPR-U 1.1

MX 6.2L MPI (OM300000 & Above) 377/V8

Model Year Standard Plug Gap (mm)
MCM General Motors 351 CID, 377 CID 2001-03 IT20 1.5

MX 6.2L MPI Horizon (OM300000 & Above) 377/V8

Model Year Standard Plug Gap (mm)
MCM General Motors 351 CID, 377 CID 2001-04 IT20 1.5

325 MCM 427/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V427 CID, 454 CID, 482 CID, 496 CID 1969-74 ITF24 0.9

330 MCM With Mallory ignition 454/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V427 CID, 454 CID, 482 CID, 496 CID 1977-81 T20R-U 0.9

Thunderbolt ignition 454/V8

Model Year Standard Plug Gap (mm)
330 MCM With 1977-81 ITF24 0.9

330 454/V8

Model Year Standard Plug Gap (mm)
330 MCM With 1982-87 T20R-U 0.9

370 TRS with Mallory ignition 454/V8

Model Year Standard Plug Gap (mm)
330 MCM With 1978-85 ITF24 0.9

370 TRS with Holley ignition 454/V8

Model Year Standard Plug Gap (mm)
330 MCM With 1978-85 T20R-U 0.9

370 TRS 454/V8

Model Year Standard Plug Gap (mm)
330 MCM With 1985-87 T20R-U 0.9

400 TRS with Mallory ignition 454/V8

Model Year Standard Plug Gap (mm)
330 MCM With 1980-86 ITF24 0.9

400 TRS with Holley ignition 454/V8

Model Year Standard Plug Gap (mm)
330 MCM With 1980-86 T20R-U 0.9

420 454/V8

Model Year Standard Plug Gap (mm)
330 MCM With 1987-89 T20R-U 0.9

425 454/V8

Model Year Standard Plug Gap (mm)
330 MCM With 1990-93 T20R-U 0.9

440 TRS with Mallory ignition 454/V8

Model Year Standard Plug Gap (mm)
330 MCM With 1983-86 ITF24 0.9

440 TRS with Holley ignition 454/V8

Model Year Standard Plug Gap (mm)
330 MCM With 1983-86 T20R-U 0.9

450 454/V8

Model Year Standard Plug Gap (mm)
330 MCM With 1995-96 T20R-U 0.9

454 Mag.Alpha 454/V8

Model Year Standard Plug Gap (mm)
330 MCM With 1986-88 T20R-U 0.9

454 Mag.Bravo 454/V8

Model Year Standard Plug Gap (mm)
330 MCM With 1988-97 T20R-U 0.9

454 Mag. EFI 454/V8

Model Year Standard Plug Gap (mm)
330 MCM With 1994-96 T20R-U 0.9

454 Mag.MPI 454/V8

Model Year Standard Plug Gap (mm)
330 MCM With 1996-01 T20R-U 1.0

7.4L Bravo 454/V8

Model Year Standard Plug Gap (mm)
330 MCM With 1988-97 T20R-U 0.9

7.4L MPI (L29) (0L010003 & Above) 454/V8

Model Year Standard Plug Gap (mm)
330 MCM With 1998-01 T20EPR-U 1.1

7.4LLX Bravo EFI 454/V8

Model Year Standard Plug Gap (mm)
330 MCM With 1996-97 T20R-U 0.9

7.4LX Bravo MPI 454/V8

Model Year Standard Plug Gap (mm)
330 MCM With 1996-97 T20R-U 0.9

460 TRS 482/V8

Model Year Standard Plug Gap (mm)
330 MCM With 1983-86 ITF24 0.9

496 Mag 496/V8

Model Year Standard Plug Gap (mm)
330 MCM With 2001-04 IT20 1.5

500 502/V8

Model Year Standard Plug Gap (mm)
330 MCM With 1994-98 T20R-U 0.9

500 Gen+ 502/V8

Model Year Standard Plug Gap (mm)
330 MCM With 1999-99 T20R-U 0.9

500 EFI 502/V8

Model Year Standard Plug Gap (mm)
330 MCM With 1998-04 T20R-U 0.9

502 Mag. 502/V8

Model Year Standard Plug Gap (mm)
330 MCM With 1990-93 T20R-U 0.9

502 EFI 502/V8

Model Year Standard Plug Gap (mm)
330 MCM With 1993-96 T20R-U 0.9

502 Mag. MPI 502/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 502CID,540 CID, 572 CID 1996-01 T20R-U 1.0

525 SC 502/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 502CID,540 CID, 572 CID 1991-95 T20R-U 0.9
MCM General Motors V8, 502CID,540 CID, 572 CID 1996-99 T20R-U 1.0

575 SCI 502/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 502CID,540 CID, 572 CID 2000-04 ITF24 1.0

600 SC (OD763875 & below) 502/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 502CID,540 CID, 572 CID 1991-93 T20R-U 0.9

600 SC (OD763875 & Above) 502/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 502CID,540 CID, 572 CID 1993-96 ITF24 0.9

600 SC (OD763876 & Above) 502/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 502CID,540 CID, 572 CID 1997-98 ITF24 1.0

500 Bulldog 540 V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 502CID,540 CID, 572 CID 1990-01 T20R-U 0.9

575 540/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 502CID,540 CID, 572 CID 1986-92 ITF24 0.9

800SC 572/V8

Model Year Standard Plug Gap (mm)
MCM General Motors V8, 502CID,540 CID, 572 CID 1997-98 ITF24 0.9

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