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Cadillac 365ci (1956–1958) specs: 365 ci 8-cylinder, 4.00 x 3.625 in (101.6 x 92.1 mm) bore and stroke. Rated 305-335 hp, 1956–1958.
The Cadillac 365ci (1956–1958) is oversquare — the 4" bore exceeds the 3.625" stroke by 10.3% — a layout that favors airflow and RPM over leverage at the crank. The 3.625" stroke puts mean piston speed at 4,000 ft/min around 6,600 RPM, which is where a production bottom end is generally considered at its limit. Each of the 8 cylinders displaces 45.6 ci (748 cc).
3 factory variants share these dimensions, rated from 305 to 335 hp across 1956–1958.
| Displacement | 365 ci |
|---|---|
| Bore | 4" |
| Stroke | 3.625" |
| Cylinders | 8 |
| Configuration | V8 |
| Compression ratio | 9.75–10.25:1 (published figures vary) |
| Bore/stroke ratio | 1.103 |
| Fuel type | gas |
|---|---|
| Advertised HP | 305–335 hp |
| Years | 1956–1958 |
| Year | Version | HP @ rpm | Torque @ rpm | Comp. | Duration int / exh | Valve lift int / exh | LSA |
|---|---|---|---|---|---|---|---|
| 1956 | gross | 305 @ 4700 | 400 lb-ft @ 3200 | 9.75:1 | 269° / 270° | 0.411" | 110.25° |
| 1957 | gross | 325 @ 4800 | — | 10:1 | 324° | 0.451" | 115° |
| 1958 | gross | 335 @ 4800 | 405 lb-ft @ 3400 | 10.25:1 | 324° | 0.451" | 113° |
Factory specification sheet. Durations are the factory's advertised figures at the basis printed on the sheet, not duration at .050" lift; lobe separation is calculated from the printed valve timing.
| Bore/stroke character | 1.103 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,625 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 45.6 ci |
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 |
|---|---|---|
| 1956 | 305 hp | — |
| 1957 | 325 hp | — |
| 1958 | 335 hp | — |
1 factory vehicle, 1956–1958. Each year opens that model's engine table.