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Chevrolet 85ci specs: 85 ci (1.4L) 4-cylinder, 3.228 x 2.606 in (82 x 66.2 mm) bore and stroke, 9.24:1 compression. Rated 57 hp, 1977.
The Chevrolet 85ci is oversquare — the 3.228" bore exceeds the 2.606" stroke by 23.9% — a layout that favors airflow and RPM over leverage at the crank. The 2.606" stroke does not reach 4,000 ft/min of mean piston speed until about 9,200 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. A rod ratio of 1.842 is long by production standards — less side-load on the cylinder wall and gentler piston acceleration around TDC, the geometry that tolerates high RPM. Each of the 4 cylinders displaces 21.3 ci (348 cc).
9.24:1 is low by modern standards and generally happy on regular pump fuel.
It is one of 2 engines in the Chevrolet 85ci family, all of them 85 ci — the differences between them are in compression, heads and rating, not displacement.
| Displacement | 85 ci / 1.4 L |
|---|---|
| Bore | 3.228" |
| Stroke | 2.606" |
| Cylinders | 4 |
| Compression ratio | 9.24:1 |
| Rod length | 4.8" |
| Rod ratio | 1.842 |
| Bore/stroke ratio | 1.239 |
| Piston deck clearance | 0.005" |
| Induction | 1-1 |
|---|---|
| Advertised HP | 57 hp |
| Years | 1977 |
| Bore/stroke character | 1.239 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 2,606 ft/min — conservative for a street engine |
| Rod ratio | 1.842 — long — less side loading on the cylinder wall, favours high RPM |
| Displacement per cylinder | 21.3 ci |
| Static compression | 9.24:1 — low by modern standards, generally happy on regular pump fuel |
| Intake valve diameter | 1.54" |
|---|---|
| Exhaust valve diameter | 1.265" |
| Chamber volume | 39 cc |
| Rocker ratio | 1.6:1 |
| Lifter type | hydraulic |
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