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Chevrolet 427ci specs: 427 ci (7.0L) 8-cylinder, 4.313 x 3.65 in (109.6 x 92.7 mm) bore and stroke, 13.5:1 compression. Rated 430 hp, 1963.
The Chevrolet 427ci is oversquare — the 4.313" bore exceeds the 3.65" stroke by 18.2% — a layout that favors airflow and RPM over leverage at the crank. The 3.65" stroke puts mean piston speed at 4,000 ft/min around 6,600 RPM, which is where a production bottom end is generally considered at its limit. A rod ratio of 1.681 is in the range most production engines fall in. Each of the 8 cylinders displaces 53.4 ci (875 cc).
13.5:1 is high for a production gasoline engine; running a ratio like that on pump fuel depends on chamber design and fuel delivery rather than the number alone.
It is one of 7 engines in the Chevrolet 427ci family, all of them 427 ci — the differences between them are in compression, heads and rating, not displacement.
| Displacement | 427 ci / 7 L |
|---|---|
| Bore | 4.313" |
| Stroke | 3.65" |
| Cylinders | 8 |
| Compression ratio | 13.5:1 |
| Rod length | 6.136" |
| Rod ratio | 1.681 |
| Bore/stroke ratio | 1.182 |
| Piston deck clearance | 0.011" |
| Induction | 2-4 |
|---|---|
| Advertised HP | 430 hp |
| Years | 1963 |
| Bore/stroke character | 1.182 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,650 ft/min — in the range typical of performance street engines |
| Rod ratio | 1.681 — moderate — the range most production V8s fall in |
| Displacement per cylinder | 53.4 ci |
| Static compression | 13.5:1 — high enough that pump premium or better is normally required |
| Intake valve diameter | 2.195" |
|---|---|
| Exhaust valve diameter | 1.725" |
| Rocker ratio | 1.75:1 |
| Lifter type | mechanical |
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