Bore, stroke, displacement and compression for all 3 Buick Big-Block V8 engines, compared side by side. Plus rod ratio and head specs where published.
| Displacement | 400–455 ci |
|---|---|
| Cylinders | 8 |
| Bore | 4.040–4.313" |
| Stroke | 3.900" |
| Compression | 10.0–10.3:1 |
| Advertised power | 340–370 hp |
| Cylinder head data | 1 of 3 engines |
| Engine | Displacement | Bore × Stroke | CR | HP |
|---|---|---|---|---|
| 455 | 455 ci | 4.3125" × 3.9" | 10:1 | 370 |
| 430 | 430 ci | 4.1875" × 3.9" | 10.25:1 | 360 |
| 400 | 400 ci | 4.04" × 3.9" | 10.25:1 | 340 |
Stroke is constant at 3.9" across the family — the displacement spread comes from bore, so these share a crank and differ in the block.
2 of 3 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.