Shelby 260ci 12:1 Specs
Shelby Shelby 260ci · 3.8" × 2.87" · 12:1 engine specs: 260 ci (4.3L), 8-cylinder, 3.8" bore x 2.87" stroke, 12:1 compression.
Dimensions
| Displacement | 260 ci / 4.3 L |
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| Bore | 3.8" |
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| Stroke | 2.87" |
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| Cylinders | 8 |
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| Compression ratio | 12:1 |
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| Rod length | 5.155" |
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| Rod ratio | 1.796 |
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| Bore/stroke ratio | 1.324 |
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| Piston deck clearance | 0" |
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Construction
| Induction | 4-2 |
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| Advertised HP | 260 hp |
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| Years | 1963 |
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What these numbers mean
| Bore/stroke character | 1.324 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
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| Mean piston speed at 6,000 RPM | 2,870 ft/min — conservative for a street engine |
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| Rod ratio | 1.796 — long — less side loading on the cylinder wall, favours high RPM |
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| Displacement per cylinder | 32.5 ci |
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| Static compression | 12:1 — high enough that pump premium or better is normally required |
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Cylinder head
| Intake valve diameter | 1.843" |
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| Exhaust valve diameter | 1.625" |
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| Chamber volume | 49 cc |
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| Rocker ratio | 1.6:1 |
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| Lifter type | mechanical |
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Similar engines
Source: NHRA blueprints — nhra.net blueprints
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