GMC 428 Specs
GMC 428 engine specs: 428 ci (7L), 8-cylinder, 4.1882" bore x 3.8" stroke, 10.75:1 compression.
Dimensions
| Displacement | 428 ci / 7 L |
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| Bore | 4.1882" |
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| Stroke | 3.8" |
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| Cylinders | 8 |
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| Compression ratio | 10.75:1 |
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| Bore/stroke ratio | 1.102 |
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Construction
| Block material | cast iron |
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| Head material | cast iron |
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| Valvetrain | OHV |
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| Fuel type | gas |
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| Advertised HP | 390 hp |
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What these numbers mean
| Bore/stroke character | 1.102 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
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| Mean piston speed at 6,000 RPM | 3,800 ft/min — in the range typical of performance street engines |
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| Displacement per cylinder | 53.5 ci |
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| Static compression | 10.75:1 — in the range that usually runs on pump premium |
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Vehicles (3)
- Pontiac Grand Prix
- Pontiac Bonneville
- Pontiac Catalina
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