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Buick 455 specs: 455 ci (7.5L) 8-cylinder, 4.313 x 3.90 in (109.5 x 99.1 mm) bore and stroke, 10:1 compression. Rated 350 hp. OHV. Rod ratio and piston speed.
The Buick Big Block V8 (455) is oversquare — the 4.3125" bore exceeds the 3.9" stroke by 10.6% — a layout that favors airflow and RPM over leverage at the crank. The 3.9" stroke puts mean piston speed at 4,000 ft/min around 6,150 RPM, which is where a production bottom end is generally considered at its limit. Each of the 8 cylinders displaces 56.9 ci (932 cc).
10:1 on iron heads is in the range that usually runs on pump premium; iron holds heat, so treat it as the less forgiving side of that range.
Factory fitments include the GS 455, Riviera, Electra.
| Displacement | 455 ci / 7.5 L |
|---|---|
| Bore | 4.3125" |
| Stroke | 3.9" |
| Cylinders | 8 |
| Compression ratio | 10:1 |
| Bore/stroke ratio | 1.106 |
| Block material | cast iron |
|---|---|
| Head material | cast iron |
| Valvetrain | OHV |
| Fuel type | gas |
| Advertised HP | 350 hp |
| Bore/stroke character | 1.106 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,900 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 56.9 ci |
| Static compression | 10:1 — in the range that usually runs on pump premium |
| Chamber volume | 59.5 cc |
|---|---|
| Rocker ratio | 1.55:1 |
| Lifter type | hydraulic |
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