See other engines in this family
GMC Small Block Chevy (1969) specs: 350 ci (5.7L) 8-cylinder, 4.00 x 3.48 in (101.6 x 88.4 mm) bore and stroke, 9:1 compression. Rated 255 hp, 1969.
The GMC Small Block Chevy (1969) is oversquare — the 4" bore exceeds the 3.4799" stroke by 14.9% — a layout that favors airflow and RPM over leverage at the crank. The 3.4799" stroke puts mean piston speed at 4,000 ft/min around 6,900 RPM, which is where a production bottom end is generally considered at its limit. Each of the 8 cylinders displaces 43.8 ci (717 cc).
9:1 on iron heads is low by modern standards and generally happy on regular pump fuel.
It is one of 27 engines in the Small Block Chevy family, sitting between the 265 ci and 400 ci members.
| Displacement | 350 ci / 5.7 L |
|---|---|
| Bore | 4" |
| Stroke | 3.4799" |
| Cylinders | 8 |
| Configuration | V8 |
| Compression ratio | 9:1 |
| Bore/stroke ratio | 1.149 |
| 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 | 255 hp |
| Years | 1969 |
| Year | Version | HP @ rpm | Torque @ rpm | Comp. | Duration int / exh | Valve lift int / exh | LSA |
|---|---|---|---|---|---|---|---|
| 1969 | LM1 gross | 255 @ 4800 | 365 lb-ft @ 3200 | 9:1 | 310° / 320° | 0.390" / 0.410" | 112.5° |
Factory specification sheet. Durations are the factory's advertised figures at the basis printed on the sheet, not duration at .050" lift; lobe separation is calculated from the printed valve timing.
| Bore/stroke character | 1.149 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,480 ft/min — conservative for a street engine |
| Displacement per cylinder | 43.8 ci |
| Static compression | 9:1 — low by modern standards, generally happy on regular pump fuel |
Each link opens the calculator with this engine's specs already filled in.
1 factory vehicle, 1969. Each year opens that model's engine table.