For the most part, Mercury does not use base engine manufacturer or cubic inches to identify their products. Early models were based on horsepower ( 260, 330, 228, etc). Most of the new production stuff is based on liters ( 5.7, 4.3, 7.4 etc). Then just to confuse things most of the high performance engines are either cubic inches (502 MAG) or horsepower - 800SC.
There is a big difference between a 7.4 and a 454 MAG.
In any case, when asking for help with parts we need to know what Mercury calls your engine.
| Horsepower | 260, 228, 330 |
| Cubic Inches | 454 Mag, 502 Mag, 350 Mag |
| Names | Scorpion, Bulldog, Horizon, EFI, Alpha, Bravo |
| Liters | 3.0, 4.3, 7.4, 8.1 |
They do not call a 260 a 350 Chevy even though that is what it is. So, to lookup parts we need the year and Mercury model designation. Some items do not require a serial number to look up, but it is helpful in all cases.
The engine serial number is sometimes on a valve cover or flame arrestor. There is also a tag riveted to the block. On sterndrive engines the tag is on the side of the block above the starter.
In most cases, we do not need the boat information.