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Buick 364ci (1957–1961) specs: 364 ci (6.0L) 8-cylinder, 4.125 x 3.40 in (104.8 x 86.4 mm) bore and stroke. Rated 250-300 hp, 1957–1961.
The Buick 364ci (1957–1961) is oversquare — the 4.125" bore exceeds the 3.4" stroke by 21.3% — a layout that favors airflow and RPM over leverage at the crank. The 3.4" stroke does not reach 4,000 ft/min of mean piston speed until about 7,050 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. A rod ratio of 1.794 is long by production standards — less side-load on the cylinder wall and gentler piston acceleration around TDC, the geometry that tolerates high RPM. Each of the 8 cylinders displaces 45.5 ci (746 cc).
It is one of 2 engines in the Buick 364ci family, all of them 364 ci — the differences between them are in compression, heads and rating, not displacement. 10 factory variants share these dimensions, rated from 250 to 300 hp across 1957–1961.
| Displacement | 364 ci / 6 L |
|---|---|
| Bore | 4.125" |
| Stroke | 3.4" |
| Cylinders | 8 |
| Configuration | V8 |
| Compression ratio | 9.5–10.5:1 (published figures vary) |
| Rod length | 6.1" |
| Rod ratio | 1.794 |
| Bore/stroke ratio | 1.213 |
| Fuel type | gas |
|---|---|
| Firing order | 1-2-7-8-4-5-6-3 |
| Advertised HP | 250–300 hp |
| Years | 1957–1961 |
| Year | Version | HP @ rpm | Torque @ rpm | Comp. | Duration int / exh | Valve lift int / exh | LSA |
|---|---|---|---|---|---|---|---|
| 1957 | gross | 250 @ 4400 | 380 lb-ft @ 2400 | 9.5:1 | 282° | 0.423" | 110° |
| 1958 | gross | 250 @ 4400 | 380 lb-ft @ 2400 | 9.5:1 | 282° | 0.378" | 110° |
| 1959 | gross | 250 @ 4400 | 384 lb-ft @ 2400 | 10.5:1 | 282° | 0.403" | 110° |
| 1960 | gross | 250 @ 4400 | 384 lb-ft | 10.25:1 | — | — | — |
| 1960 | gross | 300 @ 4400 | 405 lb-ft | 10.25:1 | — | — | — |
| 1961 | gross | 250 @ 4400 | 384 lb-ft @ 2400 | 10.25:1 | — | — | — |
| 1961 | gross | 300 @ 4400 | 405 lb-ft @ 2800 | 10.25:1 | — | — | — |
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 | 1.213 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,400 ft/min — conservative for a street engine |
| Rod ratio | 1.794 — long — less side loading on the cylinder wall, favours high RPM |
| Displacement per cylinder | 45.5 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 |
|---|---|---|
| 1957 | 250 hp | — |
| 1958 | 250 hp | — |
| 1959 | 250 hp | — |
| 1959 | 300 hp | — |
| 1960 | — | — |
| 1960 | 250 hp | — |
| 1960 | 300 hp | — |
| 1961 | — | — |
| 1961 | 250 hp | — |
| 1961 | 300 hp | — |
2 factory vehicles, 1957–1961. Each year opens that model's engine table.