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American Motors 199ci specs: 199 ci (3.3L) 6-cylinder, 3.75 x 3.00 in (95.3 x 76.2 mm) bore and stroke, 8.5:1 compression. Rated 128 hp, 1965–1970.
The American Motors 199ci is oversquare — the 3.75" bore exceeds the 3" stroke by 25.0% — a layout that favors airflow and RPM over leverage at the crank. The 3" stroke does not reach 4,000 ft/min of mean piston speed until about 8,000 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. A rod ratio of 2.042 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 33.2 ci (544 cc).
8.5:1 is low by modern standards and generally happy on regular pump fuel.
6 factory variants share these dimensions, rated at 128 hp across 1965–1970.
| Displacement | 199 ci / 3.3 L |
|---|---|
| Bore | 3.75" |
| Stroke | 3" |
| Cylinders | 6 |
| Compression ratio | 8.5:1 |
| Rod length | 6.125" |
| Rod ratio | 2.042 |
| Bore/stroke ratio | 1.25 |
| Piston deck clearance | 0.045" |
| Induction | 1-1 |
|---|---|
| Advertised HP | 128 hp |
| Years | 1965–1970 |
| Bore/stroke character | 1.250 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,000 ft/min — conservative for a street engine |
| Rod ratio | 2.042 — long — less side loading on the cylinder wall, favours high RPM |
| Displacement per cylinder | 33.2 ci |
| Static compression | 8.5:1 — low by modern standards, generally happy on regular pump fuel |
| Intake valve diameter | 1.787" |
|---|---|
| Exhaust valve diameter | 1.406" |
| Chamber volume | 53.5 cc |
| Rocker ratio | 1.5:1 |
| Lifter type | hydraulic |
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 |
|---|---|---|
| 1965 | 128 hp | — |
| 1966 | 128 hp | — |
| 1967 | 128 hp | — |
| 1968 | 128 hp | — |
| 1969 | 128 hp | — |
| 1970 | 128 hp | — |