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Oldsmobile 330 specs: 330 ci (5.4L) 8-cylinder, 3.938 x 3.385 in (100 x 86 mm) bore and stroke, 9:1 compression. Rated 260 hp. Rod ratio and piston speed.
The Oldsmobile Rocket (330) is oversquare — the 3.938" bore exceeds the 3.385" stroke by 16.3% — a layout that favors airflow and RPM over leverage at the crank. The 3.385" stroke does not reach 4,000 ft/min of mean piston speed until about 7,100 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 8 cylinders displaces 41.3 ci (676 cc).
9:1 on iron heads is low by modern standards and generally happy on regular pump fuel.
It is one of 15 engines in the Rocket family, sitting between the 260 ci and 455 ci members. Factory fitments include the Oldsmobile Cutlass, Oldsmobile F-85, Oldsmobile Jetstar 88.
| Displacement | 330 ci / 5.4 L |
|---|---|
| Bore | 3.938" |
| Stroke | 3.385" |
| Cylinders | 8 |
| Compression ratio | 9:1 |
| Bore/stroke ratio | 1.163 |
| Block material | cast iron |
|---|---|
| Head material | cast iron |
| Valvetrain | OHV |
| Fuel type | gas |
| Advertised HP | 260 hp |
| Bore/stroke character | 1.163 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,385 ft/min — conservative for a street engine |
| Displacement per cylinder | 41.3 ci |
| Static compression | 9:1 — low by modern standards, generally happy on regular pump fuel |
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