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GMC Small Block Chevy (1967–1968) specs: 327 ci (5.4L) 8-cylinder, 4.00 x 3.25 in (101.6 x 82.6 mm) bore and stroke. Rated 240 hp, 1967–1968.
The GMC Small Block Chevy (1967–1968) is oversquare — the 4" bore exceeds the 3.25" stroke by 23.1% — a layout that favors airflow and RPM over leverage at the crank. The 3.25" stroke does not reach 4,000 ft/min of mean piston speed until about 7,400 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 8 cylinders displaces 40.9 ci (670 cc).
It is one of 27 engines in the Small Block Chevy family, sitting between the 265 ci and 400 ci members. 2 factory variants share these dimensions, rated at 240 hp across 1967–1968.
| Displacement | 327 ci / 5.4 L |
|---|---|
| Bore | 4" |
| Stroke | 3.25" |
| Cylinders | 8 |
| Configuration | V8 |
| Bore/stroke ratio | 1.231 |
| Block material | cast iron |
|---|---|
| Head material | cast iron |
| Valvetrain | OHV |
| Fuel type | gas |
| Firing order | 1-8-4-3-6-5-7-2 |
| Advertised HP | 240 hp |
| Years | 1967–1968 |
| Bore/stroke character | 1.231 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,250 ft/min — conservative for a street engine |
| Displacement per cylinder | 40.9 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 |
|---|---|---|
| 1967 | — | — |
| 1968 | 240 hp | — |
1 factory vehicle, 1967–1968. Each year opens that model's engine table.