Bore, stroke, displacement and compression for all 5 Pontiac 250ci engines, compared side by side. Plus rod ratio and head specs where published.
| Displacement | 250 ci |
|---|---|
| Cylinders | 6 |
| Bore | 3.875–3.877" |
| Stroke | 3.530–3.535" |
| Compression | 9.0–10.5:1 |
| Advertised power | 100–230 hp |
| Years | 1968–1976 |
| Cylinder head data | 3 of 5 engines |
| Engine | Displacement | Bore × Stroke | CR | HP |
|---|---|---|---|---|
| Pontiac 250ci (1975) · 105 hp | 250 ci | 3.875" × 3.53" | 9.201:1 | 105 |
| Pontiac 250ci (1968–1971) | 250 ci | 3.877" × 3.535" | — | 145–155 |
| L22 | 250 ci | 3.877" × 3.535" | — | 100–155 |
| Pontiac 250ci · 3.877" × 3.535" · 9:1 | 250 ci | 3.877" × 3.535" | 9:1 | 175 |
| Pontiac 250ci · 3.877" × 3.535" · 10.5:1 | 250 ci | 3.877" × 3.535" | 10.5:1 | 215–230 |
Both bore and stroke vary across the family, so these are separate castings rather than variations on one block.
Compression spans 9:1 to 10.5:1, so fuel requirements differ meaningfully between members — worth checking before assuming parts interchange.
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.