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Mercury 430ci (1958–1960) specs: 430 ci 8-cylinder, 4.30 x 3.70 in (109.2 x 94 mm) bore and stroke, 10.5:1 compression. Rated 310-400 hp, 1958–1960.
The Mercury 430ci (1958–1960) is oversquare — the 4.3" bore exceeds the 3.7" stroke by 16.2% — a layout that favors airflow and RPM over leverage at the crank. The 3.7" stroke puts mean piston speed at 4,000 ft/min around 6,500 RPM, which is where a production bottom end is generally considered at its limit. Each of the 8 cylinders displaces 53.8 ci (881 cc).
10.5:1 is in the range that usually runs on pump premium.
4 factory variants share these dimensions, rated from 310 to 400 hp across 1958–1960.
| Displacement | 430 ci |
|---|---|
| Bore | 4.3" |
| Stroke | 3.7" |
| Cylinders | 8 |
| Configuration | V8 |
| Compression ratio | 10.5:1 |
| Bore/stroke ratio | 1.162 |
| Fuel type | gas |
|---|---|
| Advertised HP | 310–400 hp |
| Years | 1958–1960 |
| Year | Version | HP @ rpm | Torque @ rpm | Comp. |
|---|---|---|---|---|
| 1958 | gross | 360 | 480 lb-ft | 10.5:1 |
| 1958 | gross | 400 | — | 10.5:1 |
Factory specification sheet.
| Bore/stroke character | 1.162 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,700 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 53.8 ci |
| Static compression | 10.5:1 — in the range that usually runs on pump premium |
Each link opens the calculator with this engine's specs already filled in.
These records share identical bore, stroke, displacement and compression. They differ by model year and factory power rating.
| Year | Advertised HP | Code |
|---|---|---|
| 1958 | 360 hp | — |
| 1958 | 400 hp | — |
| 1959 | 345 hp | — |
| 1960 | 310 hp | — |
3 factory vehicles, 1958–1960. Each year opens that model's engine table.