Mercruiser Block ID Codes – Small Block V8
The specific model/vintage of Mercruiser Marine Engines can be determined by looking at the last letters of the engine code which is stamped in all complete Marine Longblocks by General Motors at the time of assembly. If the serial number and/or model decals are missing, the Marine Engine code will help to determine the engine model. Refer to the drawing below for the specific engine code location on your Mercruiser Engine.
Information you need from the engine code, example M01187MH. 7=General Motor’s model year in this case 1997, BUT this could also be 1987 or 1977. MH = Type of engine. The 350 cid V8 Mercruiser models 5.7L, 350 Mag Mpi, Black Scorpion Ski, etc.
GM V8 305 cid (5.0L) – Sterndrive Models (LH rotation), flat lifters
| Model | GM Code | Comments | Flywheel Diameter in. (mm) |
| 898 | MN | 1977–1980, 1982–1984 | 12–3/4 (324) |
| 898 | MX | 1981 | 12–3/4 (324) |
| 228 | MJ | 1977–1980, 1982–1984 | 12–3/4 (324) |
| 230 | PD | 1228 MY 1981 | 12–3/4 (324) |
| 200 | MN | 1985 | 12–3/4 (324) |
| 200 | MY | 1985, start 14 in. flywheel | 14 (356) |
| 200 | PY | 1986, start full circle rear seal | 14 (356) |
| 200 | PC | 1987, start new cylinder heads | 14 (356) |
| 230 | MJ | 1985 | 12–3/4 (324) |
| 230 | MZ | 1985, start 14 in. flywheel | 14 (356) |
| 230 | PZ | 1986, start full circle rear seal | 14 (356) |
| 987 | PD | 1987, start new cylinder heads | 14 (356) |
| 5.0L | PC | 1988–1990 | 14 (356) |
| 5.0L | ZC | 1990–1995 | 14 (356) |
| 5.0LX | PD | 1988–1990 | 14 (356) |
| 5.0LX | ZD | 1990–1995 | 14 (356) |
GM V8 305 cid (5.0L) – Inboard Models (rotations shown), flat lifters
| Model | GM Code | Comments | Flywheel Diameter in. (mm) |
| 198 | MR (MS) | 1977, LH (RH) | 14 (356) |
| 228 | MA (MB) | 1977–1980, LH (RH) | 14 (356) |
| 230 | MA (MB) | 1981–1985, LH (RH) | 14 (356) |
| 230 | PA (PB) | 1986, LH (RH), start full circle rear seal | 14 (356) |
| 230 | PF (PH) | 1987, LH (RH), start new cylinder heads | 14 (356) |
| 5.0L | PF (PH) | 1988, LH (RH) | 14 (356) |
GM V8 305 cid (5.0L) Gen+ – Sterndrive Models (LH rotation), roller lifters
| Model | GM Code | Comments | Flywheel Diameter in. (mm) |
| 5.0L | ZA | 1998–2001, start Gen+, start MerCruiser 2–bbl intake,0ZA, start Toluca production | 14 (356) |
| 5.0L | ZB | 2002–UP, 2ZB, MerCruiser 2–bbl intake | 14 (356) |
| 5.0L EFI | ZA | 1998–2001, start Gen+, start MerCruiser 2–bbl intake,0ZA, start Toluca production | 14 (356) |
| 5.0L MPI | ZB | 2002–UP, 2ZB, start GM IAFM (GMEFI) | 14 (356) |
GM V8 350 cid (5.7L) with Flat Lifters – Sterndrive Models (LH rotation)
| Model | GM Code | Comments | Flywheel Diameter in. (mm) |
| 255 | WH | 1974–1976 | 12–3/4 (324) |
| 250 | WT | 1977 | 12–3/4 (324) |
| 260 | WT | 1978–1980, 1982–1985 | 12–3/4 (324) |
| 260 | WS | 1981 | 12–3/4 (324) |
| 260 | WB | 1985, start 14 in. flywheel | 14 (356) |
| 260 | AB | 1986–1987, start full circle rear seal, 7AB, start newcylinder heads | 14 (356) |
| 350 Mag | AB | 1986, start full circle rear seal | 14 (356) |
| 350 Mag | AS | 1987–1990, start new cylinder heads, GM hi–rise intake | 14 (356) |
| 350 Mag | MS | 1990–1991, start GM hi–rise intake | 14 (356) |
| 5.7L | AB | 1988–1990 | 14 (356) |
| 5.7L | MB | 1990–1995 | 14 (356) |
| 5.7L | MJ | 1996–1997, GM 2–bbl intake | 14 (356) |
| 5.7L Bravo | AS | 1989–1990, start new cylinder heads, GM hi–rise intake | 14 (356) |
| 5.7L Bravo | MS | 1990–1991, start GM hi–rise intake | 14 (356) |
GM V8 350 cid (5.7L) with Flat Lifters – Ski Models (rotations shown)
| Model | GM Code | Comments | Flywheel Diameter in (mm) |
| 5.7L | WB (WR) | 1985, LH (RH) | 14 (356) |
| 5.7L | AB (AR) | 1986–1990, LH (RH), start full circle rear seal, 7AB (AR), startnew cylinder heads | 14 (356) |
| 5.7L | MB (MR) | 1990–1993, LH (RH) | 14 (356) |
| 5.7L | MB (NR) | 1993–1995, LH (RH) | 14 (356) |
| 5.7L | MJ | 1996–1997, LH, start GM 2–bbl intake | 14 (356) |
GM V8 350 cid (5.7L) with Flat Lifters – Inboard Models (rotations shown)
| Model | GM Code | Comments | Flywheel Diameter in. (mm) |
| 255 | WH (WJ) | 1975, LH (RH) | 14 (356) |
| 255 | WN (WR) | 1976–1980, LH (RH) | 14 (356) |
| 260 | WN (WR) | 1981–1985, LH (RH) | 14 (356) |
| 260 | AN (AR) | 1986–1987, LH (RH), start full circle rear seal, 7AN (AR), LH(RH), start new cylinder heads | 14 (356) |
| 5.7L | AN (AR) | 1988–1990, LH (RH) | 14 (356) |
| 5.7L | MN (MR) | 1991–1993, LH (RH) | 14 (356) |
| 5.7L | NN (NR) | 1993–1995, LH (RH) | 14 (356) |
Mercury Racing built Sterndrive Models (LH rotation), 4 bolt mains
| Model | GM Code | Comments | Flywheel Diameter in. (mm) |
| 280 | WK | 1975–1976, GM hi–rise intake | 12–3/4 (324) |
| 300 Tempest | WK | 1984–1985 | 12–3/4 (324) |
| 300 Tempest | AK | 1986, start 14 in. flywheel, full circle rear seal | 14 (356) |
| HP320 EFI | AK | 1987–1989, Mercury Marine MPI intake | 14 (356) |
GM V8 350 cid (5.7L) with Roller Lifters – Sterndrive Models (LH rotation)
| Model | GM Code | Comments | Flywheel Diameter in. (mm) |
| 5.7L | CD | 1991–1993, start GM hi–rise intake, Bravo only | 14 (356) |
| 5.7L | MD | 1993–1995 | 14 (356) |
| 5.7L | MJ | 1997, 7MJ, start GM 2–bbl intake | 14 (356) |
| 5.7LX | MD | 1996–1997, start GM hi–rise intake | 14 (356) |
| 350 Mag | CD | 1991–1993, start GM hi–rise intake | 14 (356) |
| 350 Mag | MD | 1993–1997 | 14 (356) |
| 350 Mag MPI | MH | 1995, start MerCruiser MPI intake, Bravo | 14 (356) |
GM V8 350 cid (5.7L) with Roller Lifters – Ski Models (LH rotation)
| Model | GM Code | Comments | Flywheel Diameter in. (mm) |
| 5.7L | MJ | 1997, 7MJ, GM 2–bbl intake | 14 (356) |
| 350 Mag | CD | 1991–1993, start GM hi–rise intake | 14 (356) |
| 350 Mag | MD | 1993–1997 | 14 (356) |
| 350 Mag MPI | MH | 1995–1996, start MerCruiser MPI intake | 14 (356) |
GM V8 350 cid (5.7L) with Roller Lifters – Inboard Models (LH rotation)
| Model | GM Code | Comments | Flywheel Diameter in. (mm) |
| 5.7L | MM | 1996–1997, start GM hi–rise intake | 14 (356) |
GM V8 350 cid (5.7L) Gen+ – Sterndrive Models (LH rotation), with roller lifters
| Model | GM Code | Comments | Flywheel Diameter in. (mm) |
| 5.7L | MH | 1998–2002, start MerCruiser 2–bbl intake, 0MH, startToluca production | 14 (356) |
| 5.7L | MN | 2002–UP, MerCruiser 2–bbl intake | 14 (356) |
| 5.7L EFI | MH | 1998–2002, (TBI), 0MH, start Toluca production. | 14 (356) |
| 5.7LX EFI | MH | 1996–1997, 6MH, start Gen+, Bravo (TBI) | 14 (356) |
| 350 Mag EFI | MH | 1996–1997, 6MH, start Gen+, Alpha (TBI) | 14 (356) |
| 350 Mag MPI | MH | 1996–1997, 6MH, start Gen+, Bravo, start MerCruiserMPI intake | 14 (356) |
| 350 Mag MPI | MH | 1998–2002, start low MerCruiser MPI intake, 0MH,start Toluca production | 14 (356) |
| 350 Mag MPI | MN | 2002, low MerCruiser MPI intake | 14 (356) |
| 350 Mag MPI | MN | 2002–UP, start GM IAFM (GMEFI) intake | 14 (356) |
GM V8 350 cid (5.7L) Gen+ – Ski Models (LH rotation)
| Model | GM Code | Comments | Flywheel Diameter in. (mm) |
| 5.7L | MH | 1998–2002, start MerCruiser 2–bbl intake, 0MH,start Toluca production | 14 (356) |
| 5.7L | MN | 2002–UP, MerCruiser 2–bbl carb intake | 14 (356) |
| 350 Mag EFI | MH | 1996–1997, 6MH, start Gen+ (TBI) | 14 (356) |
| 350 Mag MPI | MH | 1998–2002, start low MerCruiser MPI intake, 0MH,start Toluca production | 14 (356) |
| 350 Mag MPI | MN | 2002, low MerCruiser MPI intake | 14 (356) |
| 350 Mag MPI | MN | 2002–UP, start GM IAFM (GMEFI) intake | 14 (356) |
| Black Scorpion | MH | 1996–2002, 6MH, start Gen+, MerCruiser MPIintake, 0MH, start Toluca production | 14 (356) |
| Black Scorpion | MN | 2002–UP, MerCruiser MPI intake | 14 (356) |
GM V8 350 cid (5.7L) Gen+ – Inboard Models (LH rotation)
| Model | GM Code | Comments | Flywheel Diameter in. (mm) |
| 5.7L | MK | 1998–2002, start MerCruiser 2–bbl intake, 0MK, startToluca production | 14 (356) |
| 5.7L | ML | 2002–UP, MerCruiser 2–bbl carb intake | 14 (356) |
| 5.7L EFI | MK | 1997, (TBI) | 14 (356) |
| 350 Mag MPI | MK | 1998–2002, low MerCruiser MPI intake, 0MK, startToluca production | 14 (356) |
| 350 Mag MPI | ML | 2002, low MerCruiser MPI intake | 14 (356) |
| 350 Mag MPI | ML | 2002–UP, start GM IAFM (GMEFI) intake | 14 (356) |
GM V8 377 cid (6.2L) Gen+ – Sterndrive Models (LH rotation), with roller lifters
| Model | GM Code | Comments | Flywheel Diameter in. (mm) |
| Scorpion 377 | MH | 2000–2002, Bravo, MerCruiser MPI intake, this modelonly built by Mercury Racing | 14 (356) |
| Scorpion 377 | MN | 2002–UP, Bravo, MerCruiser MPI intake, this modelonly built by Mercury Racing | 14 (356) |
| MX 6.2 MPI | MH | A 2001–2002, Bravo, start low MerCruiser MPI intake,built by Mercury MerCruiser, P/N 431–862562camshaft | 14 (356) |
| MX 6.2 MPI | MN | A 2002, Bravo, low MerCruiser MPI intake, with P/N431–862562 camshaft | 14 (356) |
| MX 6.2 MPI | MN | B 2002–UP, Bravo, start GM IAFM (GMEFI) intake,with P/N 431–862562T 1 camshaft | 14 (356) |
GM V8 377 cid (6.2L) Gen+ – Ski Models (LH rotation)
| Model | GM Code | Comments | Flywheel Diameter in. (mm) |
| Scorpion 377 | MH | 1997–2000, MerCruiser MPI intake, this model onlybuilt by Mercury Racing | 14 (356) |
| Black Scorpion | MH A | 2001–2002, start MerCruiser MPI intake, built byMercury MerCruiser, with P/N 431–862562camshaft | 14 (356) |
| Black Scorpion | MN A | 2002, MerCruiser MPI intake, with P/N 431–862562camshaft | 14 (356) |
| Black Scorpion | MN B | 2002–UP, MerCruiser MPI intake, with P/N 431–862562T 1 camshaft | 14 (356) |
GM V8 377 cid (6.2L) Gen+ – Inboard Models (LH rotation)
| Model | GM Code | Comments | Flywheel Diameter in. (mm) |
| MX 6.2 MPI | MK A | 2001–2002, start low MerCruiser MPI intake, built byMercury MerCruiser, with P/N 431–862562 camshaft | 14 (356) |
| MX 6.2 MPI | ML A | 2002, with P/N 431–862562 camshaft | 14 (356) |
| MX 6.2 MPI | ML B | 2002–UP, start GM IAFM (GMEFI) intake, with P/N431–862562T 1 camshaft | 14 (356) |
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