GMC 261 Specs
GMC 261 engine specs: 261 ci (4.28L), 6-cylinder, 3.8752" bore x 3.6882" stroke, 8:1 compression.
Dimensions
| Displacement | 261 ci / 4.28 L |
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| Bore | 3.8752" |
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| Stroke | 3.6882" |
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| Cylinders | 6 |
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| Compression ratio | 8:1 |
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| Bore/stroke ratio | 1.051 |
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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 | 140 hp |
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What these numbers mean
| Bore/stroke character | 1.051 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
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| Mean piston speed at 6,000 RPM | 3,688 ft/min — in the range typical of performance street engines |
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| Displacement per cylinder | 43.5 ci |
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| Static compression | 8:1 — low by modern standards, generally happy on regular pump fuel |
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Vehicles (3)
- Chevrolet Task Force trucks (heavy duty)
- GMC trucks (heavy duty)
- Chevrolet Bel Air (export/heavy duty)
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