Bore, stroke, displacement and compression for all 7 Chevrolet 427ci engines, compared side by side. Plus rod ratio and head specs where published.
| Displacement | 427 ci |
|---|---|
| Cylinders | 8 |
| Bore | 4.125–4.313" |
| Stroke | 3.650–4.000" |
| Compression | 10.3–13.5:1 |
| Advertised power | 335–505 hp |
| Years | 1963–2023 |
| Cylinder head data | 7 of 7 engines |
| Engine | Displacement | Bore × Stroke | CR | HP |
|---|---|---|---|---|
| Chevrolet 427ci (2006) · 505 hp | 427 ci | 4.125" × 4" | 11:1 | 505 |
| Chevrolet 427ci · 4.125" × 4.000" | 427 ci | 4.125" × 4" | — | 425–470 |
| Chevrolet 427ci · 4.313" × 3.65" · 13.5:1 | 427 ci | 4.313" × 3.65" | 13.5:1 | 430 |
| Chevrolet 427ci · 4.25" × 3.766" · 10.25:1 | 427 ci | 4.25" × 3.766" | 10.25:1 | 335–400 |
| Chevrolet 427ci · 4.25" × 3.766" · 11:1 | 427 ci | 4.25" × 3.766" | 11:1 | 425–435 |
| Chevrolet 427ci · 4.25" × 3.766" · 12.5:1 | 427 ci | 4.25" × 3.766" | 12.5:1 | 430 |
| Chevrolet 427ci · 4.25" × 3.766" · 12:1 | 427 ci | 4.25" × 3.766" | 12:1 | 430 |
Both bore and stroke vary across the family, so these are separate castings rather than variations on one block.
Compression spans 10.25:1 to 13.5:1, so fuel requirements differ meaningfully between members — worth checking before assuming parts interchange.
5 of 7 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.