GMC 250ci specs: 3.875 x 3.53 in (98.4 x 89.7 mm) bore and stroke, shared by all 2 versions. Displacement, compression and factory ratings, plus rod ratio.
| Displacement | 250 ci |
|---|---|
| Cylinders | 6 |
| Bore | 3.875" |
| Stroke | 3.530" |
| Compression | 8.3:1 |
| Advertised power | 105–155 hp |
| Years | 1967–1984 |
| Engine | Displacement | Bore × Stroke | CR | HP |
|---|---|---|---|---|
| GMC 250ci (1967–1978) | 250 ci | 3.875" × 3.53" | — | 105–155 |
| LE3 | 250 ci | 3.875" × 3.53" | 8.3:1 | 115 |
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.