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Chevrolet 402ci specs: 402 ci (6.6L) 8-cylinder, 4.125 x 3.766 in (104.8 x 95.7 mm) bore and stroke, 9.281:1 compression. Rated 210-300 hp, 1971–1972.
The Chevrolet 402ci is oversquare — the 4.125" bore exceeds the 3.766" stroke by 9.5% — 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 50.3 ci (823 cc).
9.281:1 on iron heads is low by modern standards and generally happy on regular pump fuel.
It is one of 8 engines in the Chevrolet 402ci family, all of them 402 ci — the differences between them are in compression, heads and rating, not displacement. 3 factory variants share these dimensions, rated from 210 to 300 hp across 1971–1972.
| Displacement | 402 ci / 6.6 L |
|---|---|
| Bore | 4.125" |
| Stroke | 3.766" |
| Cylinders | 8 |
| Configuration | V8 |
| Compression ratio | 9.281:1 |
| Rod length | 6.136" |
| Rod ratio | 1.629 |
| Bore/stroke ratio | 1.095 |
| Piston deck clearance | 0.008" |
| Block material | cast iron |
|---|---|
| Head material | cast iron |
| Valvetrain | OHV |
| Fuel type | gas |
| Advertised HP | 210–300 hp |
| Years | 1971–1972 |
| Bore/stroke character | 1.095 — 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 | 50.3 ci |
| Static compression | 9.281:1 — low by modern standards, generally happy on regular pump fuel |
| Intake valve diameter | 2.07" |
|---|---|
| Exhaust valve diameter | 1.725" |
| Chamber volume | 96.4 cc |
| Rocker ratio | 1.7:1 |
| Lifter type | hydraulic |
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These records share identical bore, stroke, displacement and compression. They differ by model year and factory power rating.
| Year | Advertised HP | Code |
|---|---|---|
| 1971 | 300 hp | — |
| 1972 | 210 hp | — |
| 1972 | 240 hp | — |