Buick 403ci specs: 4.351 x 3.385 in (110.5 x 86 mm) bore and stroke, shared by all 2 versions. Displacement, compression and factory ratings, plus rod ratio.
| Displacement | 403 ci |
|---|---|
| Cylinders | 8 |
| Bore | 4.351" |
| Stroke | 3.385" |
| Compression | 9.2:1 |
| Advertised power | 175–185 hp |
| Years | 1978–1979 |
| Cylinder head data | 1 of 2 engines |
| Engine | Displacement | Bore × Stroke | CR | HP |
|---|---|---|---|---|
| 1979 403 175HP | 403 ci | 4.351" × 3.385" | 9.181:1 | 175 |
| L80 | 403 ci | 4.351" × 3.385" | — | 185 |
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.