Bore, stroke, displacement and compression for all 4 Chevrolet 307ci engines, compared side by side. Plus rod ratio and head specs where published.
| Displacement | 307 ci |
|---|---|
| Cylinders | 8 |
| Bore | 3.800–3.875" |
| Stroke | 3.250–3.385" |
| Compression | 9.2–9.7:1 |
| Advertised power | 115–200 hp |
| Years | 1968–1990 |
| Cylinder head data | 1 of 4 engines |
| Engine | Displacement | Bore × Stroke | CR | HP |
|---|---|---|---|---|
| Chevrolet 307ci · 3.875" × 3.250" · 9.651:1 | 307 ci | 3.875" × 3.25" | 9.651:1 | 115–130 |
| Chevrolet 307ci · 3.800" × 3.385" · 9.241:1 | 307 ci | 3.8" × 3.385" | 9.241:1 | 140 |
| Chevrolet 307ci (1968–1972) | 307 ci | 3.875" × 3.25" | — | 135–200 |
| L14 | 307 ci | 3.875" × 3.25" | — | 135–200 |
Both bore and stroke vary across the family, so these are separate castings rather than variations on one block.
All are oversquare — bore larger than stroke, which favours revs over low-end torque.
Each engine page carries rod ratio, mean piston speed, bore/stroke character and cylinder head specs where published, and links into the calculators with its dimensions already filled in.