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Buick Small-Block V8 specs: 350 ci (5.7L) 8-cylinder, 3.80 x 3.85 in (96.5 x 97.8 mm) bore and stroke, 10.25:1 compression. Rated 280-315 hp, 1968–1970.
The Buick Small-Block V8 is close to square: 3.8" bore against 3.85" stroke, within 1.3%, which splits the difference between a high-revving layout and a torque layout. The 3.85" stroke puts mean piston speed at 4,000 ft/min around 6,250 RPM, which is where a production bottom end is generally considered at its limit. Each of the 8 cylinders displaces 43.8 ci (717 cc).
10.25:1 is in the range that usually runs on pump premium.
It is one of 8 engines in the Buick Small-Block V8 family, the largest at 350 ci. 3 factory variants share these dimensions, rated from 280 to 315 hp across 1968–1970. Factory fitments include the Buick Skylark, Buick LeSabre, Buick Riviera and 6 others.
| Displacement | 350 ci / 5.7 L |
|---|---|
| Bore | 3.8" |
| Stroke | 3.85" |
| Cylinders | 8 |
| Compression ratio | 10.25:1 |
| Bore/stroke ratio | 0.987 |
| Block material | cast iron |
|---|---|
| Valvetrain | OHV |
| Fuel type | gas |
| Advertised HP | 280–315 hp |
| Years | 1968–1970 |
| Bore/stroke character | 0.987 — square — bore and stroke are within 5%, a balanced compromise |
|---|---|
| Mean piston speed at 6,000 RPM | 3,850 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 43.8 ci |
| Static compression | 10.25:1 — 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 |
|---|---|---|
| 1968 | 280 hp | 350-4 |
| 1969 | 280 hp | 350-4 |
| 1970 | 315 hp | 350-4 High Performance |