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GMC 351E specs: 351 ci 6-cylinder, 4.563 x 3.58 in (115.9 x 90.9 mm) bore and stroke. Rated 220 hp, 1966–1968. Used in the GMC C/K Pickup.
The GMC 351E is oversquare — the 4.5625" bore exceeds the 3.58" stroke by 27.4% — a layout that favors airflow and RPM over leverage at the crank. The 3.58" stroke puts mean piston speed at 4,000 ft/min around 6,700 RPM, which is where a production bottom end is generally considered at its limit. Each of the 6 cylinders displaces 58.5 ci (959 cc).
3 factory variants share these dimensions, rated at 220 hp across 1966–1968.
| Displacement | 351 ci |
|---|---|
| Bore | 4.5625" |
| Stroke | 3.58" |
| Cylinders | 6 |
| Configuration | V6 |
| Bore/stroke ratio | 1.274 |
| Fuel type | gas |
|---|---|
| Advertised HP | 220 hp |
| Years | 1966–1968 |
| Bore/stroke character | 1.274 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,580 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 58.5 ci |
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 |
|---|---|---|
| 1966 | 220 hp | 351E |
| 1967 | 220 hp | 351E |
| 1968 | 220 hp | 351E |
1 factory vehicle, 1966–1968. Each year opens that model's engine table.