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Buick 198ci specs: 198 ci (3.2L) 6-cylinder, 3.625 x 3.20 in (92.1 x 81.3 mm) bore and stroke, 8.8:1 compression. Rated 135 hp, 1962–1963.
The Buick 198ci is oversquare — the 3.625" bore exceeds the 3.2" stroke by 13.3% — a layout that favors airflow and RPM over leverage at the crank. The 3.2" stroke does not reach 4,000 ft/min of mean piston speed until about 7,500 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. A rod ratio of 1.831 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 6 cylinders displaces 33.0 ci (541 cc).
8.8:1 is low by modern standards and generally happy on regular pump fuel.
2 factory variants share these dimensions, rated at 135 hp across 1962–1963.
| Displacement | 198 ci / 3.2 L |
|---|---|
| Bore | 3.625" |
| Stroke | 3.2" |
| Cylinders | 6 |
| Compression ratio | 8.8:1 |
| Rod length | 5.86" |
| Rod ratio | 1.831 |
| Bore/stroke ratio | 1.133 |
| Piston deck clearance | 0.256" |
| Induction | 1-2 |
|---|---|
| Advertised HP | 135 hp |
| Years | 1962–1963 |
| Bore/stroke character | 1.133 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,200 ft/min — conservative for a street engine |
| Rod ratio | 1.831 — long — less side loading on the cylinder wall, favours high RPM |
| Displacement per cylinder | 33.0 ci |
| Static compression | 8.8:1 — low by modern standards, generally happy on regular pump fuel |
| Intake valve diameter | 1.5" |
|---|---|
| Exhaust valve diameter | 1.313" |
| Chamber volume | 42.6 cc |
| Rocker ratio | 1.6:1 |
| Lifter type | hydraulic |
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These records share identical bore, stroke, displacement and compression. They differ by model year and factory power rating.
| Year | Advertised HP | Code |
|---|---|---|
| 1962 | 135 hp | — |
| 1963 | 135 hp | — |