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Mercury C-code / J-code specs: 429 ci (7.0L) 8-cylinder, 4.36 x 3.59 in (110.7 x 91.2 mm) bore and stroke. Rated 370 hp, 1971. Used in the Mercury Cougar.
The Mercury C-code / J-code is oversquare — the 4.36" bore exceeds the 3.59" stroke by 21.4% — a layout that favors airflow and RPM over leverage at the crank. The 3.59" stroke puts mean piston speed at 4,000 ft/min around 6,700 RPM, which is where a production bottom end is generally considered at its limit. Each of the 8 cylinders displaces 53.6 ci (879 cc).
It is one of 10 engines in the 385 family, the smallest at 429 ci.
| Displacement | 429 ci / 7 L |
|---|---|
| Bore | 4.36" |
| Stroke | 3.59" |
| Cylinders | 8 |
| Configuration | V8 |
| Bore/stroke ratio | 1.214 |
| Block material | cast iron |
|---|---|
| Head material | cast iron |
| Valvetrain | OHV |
| Fuel type | gas |
| Advertised HP | 370 hp |
| Years | 1971 |
| Bore/stroke character | 1.214 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,590 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 53.6 ci |
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