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Chevrolet 302ci specs: 302 ci (4.9L) 8-cylinder, 4.002 x 3.005 in (101.7 x 76.3 mm) bore and stroke, 11:1 compression. Rated 290 hp, 1967–1969.
The Chevrolet 302ci is oversquare — the 4.002" bore exceeds the 3.005" stroke by 33.2% — a layout that favors airflow and RPM over leverage at the crank. The 3.005" 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 1.897 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 37.8 ci (619 cc).
11:1 is high enough that pump premium or better is normally required.
It is one of 2 engines in the Chevrolet 302ci family, all of them 302 ci — the differences between them are in compression, heads and rating, not displacement. 3 factory variants share these dimensions, rated at 290 hp across 1967–1969.
| Displacement | 302 ci / 4.9 L |
|---|---|
| Bore | 4.002" |
| Stroke | 3.005" |
| Cylinders | 8 |
| Compression ratio | 11:1 |
| Rod length | 5.7" |
| Rod ratio | 1.897 |
| Bore/stroke ratio | 1.332 |
| Piston deck clearance | 0.002" |
| Induction | 1-4 |
|---|---|
| Advertised HP | 290 hp |
| Years | 1967–1969 |
| Bore/stroke character | 1.332 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,005 ft/min — conservative for a street engine |
| Rod ratio | 1.897 — long — less side loading on the cylinder wall, favours high RPM |
| Displacement per cylinder | 37.8 ci |
| Static compression | 11:1 — high enough that pump premium or better is normally required |
| Intake valve diameter | 2.023" |
|---|---|
| Exhaust valve diameter | 1.605" |
| Chamber volume | 61.2 cc |
| Rocker ratio | 1.5:1 |
| Lifter type | mechanical |
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 |
|---|---|---|
| 1967 | 290 hp | — |
| 1968 | 290 hp | — |
| 1969 | 290 hp | — |