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GMC 316 specs: 316.6 ci (5.2L) 8-cylinder, 3.938 x 3.25 in (100 x 82.6 mm) bore and stroke, 8.9:1 compression. Rated 205 hp. OHV. Rod ratio and piston speed.
The GMC Pontiac V8 (316) is oversquare — the 3.9375" bore exceeds the 3.25" stroke by 21.2% — 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 39.6 ci (649 cc).
8.9:1 on iron heads is low by modern standards and generally happy on regular pump fuel.
It is one of 9 engines in the Pontiac V8 family, sitting between the 287 ci and 455 ci members. Factory fitments include the Pontiac Chieftain, Pontiac Star Chief, Pontiac Catalina.
| Displacement | 316.6 ci / 5.2 L |
|---|---|
| Bore | 3.9375" |
| Stroke | 3.25" |
| Cylinders | 8 |
| Compression ratio | 8.9:1 |
| Bore/stroke ratio | 1.212 |
| Piston deck clearance | 0" |
| Block material | cast iron |
|---|---|
| Head material | cast iron |
| Valvetrain | OHV |
| Fuel type | gas |
| Advertised HP | 205 hp |
| Bore/stroke character | 1.212 — 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 | 39.6 ci |
| Static compression | 8.9:1 — low by modern standards, generally happy on regular pump fuel |
| Intake valve diameter | 1.78" |
|---|---|
| Exhaust valve diameter | 1.5" |
| Chamber volume | 69.6 cc |
| Rocker ratio | 1.5:1 |
| Lifter type | hydraulic |
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