Pontiac 421ci 11:1 Specs
Pontiac Pontiac 421ci · 4.093" × 4" · 11:1 engine specs: 421 ci (6.9L), 8-cylinder, 4.093" bore x 4" stroke, 11:1 compression.
Dimensions
| Displacement | 421 ci / 6.9 L |
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| Bore | 4.093" |
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| Stroke | 4" |
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| Cylinders | 8 |
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| Compression ratio | 11:1 |
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| Rod length | 6.625" |
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| Rod ratio | 1.656 |
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| Bore/stroke ratio | 1.023 |
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| Piston deck clearance | 0" |
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Construction
| Induction | 2-4 |
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| Advertised HP | 405 hp |
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| Years | 1962 |
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What these numbers mean
| Bore/stroke character | 1.023 — square — bore and stroke are within 5%, a balanced compromise |
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| Mean piston speed at 6,000 RPM | 4,000 ft/min — in the range typical of performance street engines |
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| Rod ratio | 1.656 — moderate — the range most production V8s fall in |
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| Displacement per cylinder | 52.6 ci |
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| Static compression | 11:1 — high enough that pump premium or better is normally required |
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Cylinder head
| Chamber volume | 66.8 cc |
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| Rocker ratio | 1.65:1 |
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| Lifter type | mechanical |
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Similar engines
Source: NHRA blueprints — nhra.net blueprints
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