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Buick 263ci (1951–1953) specs: 263 ci 8-cylinder, 3.188 x 4.125 in (81 x 104.8 mm) bore and stroke. Rated 120-128 hp, 1951–1953. Used in the Buick Special.
The Buick 263ci (1951–1953) is undersquare — the 4.125" stroke exceeds the 3.1875" bore by 22.7% — a layout that trades peak RPM for leverage and torque low in the range. The 4.125" stroke puts mean piston speed at 4,000 ft/min around 5,800 RPM, which is where a production bottom end is generally considered at its limit. Each of the 8 cylinders displaces 32.9 ci (539 cc).
6 factory variants share these dimensions, rated from 120 to 128 hp across 1951–1953.
| Displacement | 263 ci |
|---|---|
| Bore | 3.1875" |
| Stroke | 4.125" |
| Cylinders | 8 |
| Configuration | V8 |
| Compression ratio | 6.6–7.2:1 (published figures vary) |
| Bore/stroke ratio | 0.773 |
| Fuel type | gas |
|---|---|
| Advertised HP | 120–128 hp |
| Years | 1951–1953 |
| Year | Version | HP @ rpm | Torque @ rpm | Comp. | Duration int / exh | Valve lift int / exh | LSA |
|---|---|---|---|---|---|---|---|
| 1951 | gross | 120 @ 3600 | 215 lb-ft @ 2000 | 6.6:1 | 261° / 257° | 0.348" | 112° |
| 1952 | gross | 120 @ 3600 | 215 lb-ft @ 2000 | 6.6:1 | 261° / 257° | 0.348" | 112° |
| 1952 | gross | 128 @ 3600 | 225 lb-ft @ 2000 | 7.2:1 | 261° / 257° | 0.348" | 112° |
| 1953 | gross | 125 | — | 7:1 | — | — | — |
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 | 0.773 — undersquare — stroke exceeds bore, which favours low-end torque |
|---|---|
| Mean piston speed at 6,000 RPM | 4,125 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 32.9 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 |
|---|---|---|
| 1951 | 120 hp | — |
| 1951 | 128 hp | — |
| 1952 | 120 hp | — |
| 1952 | 128 hp | — |
| 1953 | — | — |
| 1953 | 125 hp | — |
1 factory vehicle, 1951–1953. Each year opens that model's engine table.