See other engines in this family
Chevrolet 427ci specs: 427 ci (7.0L) 8-cylinder, 4.25 x 3.766 in (108 x 95.7 mm) bore and stroke, 12.5:1 compression. Rated 430 hp, 1968.
The Chevrolet 427ci is oversquare — the 4.25" bore exceeds the 3.766" stroke by 12.9% — a layout that favors airflow and RPM over leverage at the crank. The 3.766" stroke puts mean piston speed at 4,000 ft/min around 6,350 RPM, which is where a production bottom end is generally considered at its limit. A rod ratio of 1.629 is in the range most production engines fall in. Each of the 8 cylinders displaces 53.4 ci (875 cc).
12.5:1 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 | 4.25" |
| Stroke | 3.766" |
| Cylinders | 8 |
| Compression ratio | 12.5:1 |
| Rod length | 6.136" |
| Rod ratio | 1.629 |
| Bore/stroke ratio | 1.129 |
| Piston deck clearance | 0.002" |
| Induction | 1-4 |
|---|---|
| Advertised HP | 430 hp |
| Years | 1968 |
| Bore/stroke character | 1.129 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,766 ft/min — in the range typical of performance street engines |
| Rod ratio | 1.629 — moderate — the range most production V8s fall in |
| Displacement per cylinder | 53.4 ci |
| Static compression | 12.5:1 — high enough that pump premium or better is normally required |
| Intake valve diameter | 2.195" |
|---|---|
| Exhaust valve diameter | 1.845" |
| Chamber volume | 103.3 cc |
| Rocker ratio | 1.7:1 |
| Lifter type | mechanical |
Each link opens the calculator with this engine's specs already filled in.