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Mercury W-code specs: 427 ci (7.0L) 8-cylinder, 4.228 x 3.787 in (107.4 x 96.2 mm) bore and stroke. Rated 390 hp, 1968. Used in the Mercury Cougar. OHV.
The Mercury W-code is oversquare — the 4.2283" bore exceeds the 3.7874" stroke by 11.6% — a layout that favors airflow and RPM over leverage at the crank. The 3.7874" stroke puts mean piston speed at 4,000 ft/min around 6,350 RPM, which is where a production bottom end is generally considered at its limit. Each of the 8 cylinders displaces 53.4 ci (875 cc).
It is one of 34 engines in the FE family, sitting between the 332 ci and 428 ci members.
| Displacement | 427 ci / 7 L |
|---|---|
| Bore | 4.2283" |
| Stroke | 3.7874" |
| Cylinders | 8 |
| Configuration | V8 |
| Bore/stroke ratio | 1.116 |
| Block material | cast iron |
|---|---|
| Head material | cast iron |
| Valvetrain | OHV |
| Fuel type | gas |
| Advertised HP | 390 hp |
| Years | 1968 |
| Bore/stroke character | 1.116 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,787 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 53.4 ci |
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