Buick 425ci 10.25:1 Specs
Buick Buick 425ci · 4.313" × 3.64" · 10.25:1 engine specs: 425 ci (7L), 8-cylinder, 4.313" bore x 3.64" stroke, 10.25:1 compression.
Dimensions
| Displacement | 425 ci / 7 L |
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| Bore | 4.313" |
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| Stroke | 3.64" |
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| Cylinders | 8 |
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| Compression ratio | 10.25:1 |
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| Rod length | 6.22" |
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| Rod ratio | 1.709 |
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| Bore/stroke ratio | 1.185 |
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| Piston deck clearance | 0.028" |
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Construction
| Induction | 1-4 |
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| Advertised HP | 340–360 hp |
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| Years | 1963–1966 |
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What these numbers mean
| Bore/stroke character | 1.185 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
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| Mean piston speed at 6,000 RPM | 3,640 ft/min — in the range typical of performance street engines |
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| Rod ratio | 1.709 — moderate — the range most production V8s fall in |
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| Displacement per cylinder | 53.1 ci |
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| Static compression | 10.25:1 — in the range that usually runs on pump premium |
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Cylinder head
| Intake valve diameter | 1.875" |
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| Exhaust valve diameter | 1.5" |
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| Chamber volume | 123.72 cc |
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| Rocker ratio | 1.6:1 |
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| Lifter type | hydraulic |
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Variants sharing these dimensions (6)
These records share identical bore, stroke, displacement and compression. They differ by model year and factory power rating.
| Year | Advertised HP | Code |
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| 1963 | 340 hp | — |
| 1964 | 340 hp | — |
| 1964 | 360 hp | — |
| 1965 | 340 hp | — |
| 1965 | 360 hp | — |
| 1966 | 340 hp | — |
Similar engines
Source: NHRA blueprints — nhra.net blueprints
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