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Pontiac 350ci specs: 350 ci (5.7L) 8-cylinder, 3.877 x 3.754 in (98.5 x 95.4 mm) bore and stroke, 8.301:1 compression. Rated 160-165 hp, 1976.
The Pontiac 350ci is close to square: 3.877" bore against 3.754" stroke, within 3.3%, which splits the difference between a high-revving layout and a torque layout. The 3.754" stroke puts mean piston speed at 4,000 ft/min around 6,400 RPM, which is where a production bottom end is generally considered at its limit. A rod ratio of 1.765 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 43.8 ci (717 cc).
8.301:1 on iron heads is low by modern standards and generally happy on regular pump fuel.
It is one of 13 engines in the Pontiac 350ci family, all of them 350 ci — the differences between them are in compression, heads and rating, not displacement. 2 factory variants share these dimensions, rated from 160 to 165 hp in 1976.
| Displacement | 350 ci / 5.7 L |
|---|---|
| Bore | 3.877" |
| Stroke | 3.754" |
| Cylinders | 8 |
| Configuration | V8 |
| Compression ratio | 8.301:1 |
| Rod length | 6.625" |
| Rod ratio | 1.765 |
| Bore/stroke ratio | 1.033 |
| Piston deck clearance | 0" |
| Block material | cast iron |
|---|---|
| Head material | cast iron |
| Valvetrain | OHV |
| Fuel type | gas |
| Advertised HP | 160–165 hp |
| Years | 1976 |
| Bore/stroke character | 1.033 — square — bore and stroke are within 5%, a balanced compromise |
|---|---|
| Mean piston speed at 6,000 RPM | 3,754 ft/min — in the range typical of performance street engines |
| Rod ratio | 1.765 — long — less side loading on the cylinder wall, favours high RPM |
| Displacement per cylinder | 43.8 ci |
| Static compression | 8.301:1 — low by modern standards, generally happy on regular pump fuel |
| Intake valve diameter | 2.113" |
|---|---|
| Exhaust valve diameter | 1.663" |
| Chamber volume | 73 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 |
|---|---|---|
| 1976 | 160 hp | — |
| 1976 | 165 hp | — |