Bore, stroke, displacement and compression for all 13 Pontiac 350ci engines, compared side by side. Plus rod ratio and head specs where published.
| Displacement | 350 ci |
|---|---|
| Cylinders | 8 |
| Bore | 3.800–4.001" |
| Stroke | 3.484–3.850" |
| Compression | 8.3–10.8:1 |
| Advertised power | 145–330 hp |
| Years | 1969–1998 |
| Cylinder head data | 6 of 13 engines |
| Engine | Displacement | Bore × Stroke | CR | HP |
|---|---|---|---|---|
| Pontiac 350ci · 3.800" × 3.850" · 9.611:1 | 350 ci | 3.8" × 3.85" | 9.611:1 | 145–165 |
| Pontiac 350ci · 3.800" × 3.850" · 8.301:1 | 350 ci | 3.8" × 3.85" | 8.301:1 | 155–175 |
| Pontiac 350ci · 3.877" × 3.754" · 8.301:1 | 350 ci | 3.877" × 3.754" | 8.301:1 | 160–165 |
| Pontiac 350ci · 4.001" × 3.484" · 10.22:1 | 350 ci | 4.001" × 3.484" | 10.22:1 | 225–230 |
| Pontiac 350ci (1991) · 240 hp | 350 ci | 4.001" × 3.484" | 10.75:1 | 240 |
| Pontiac 350ci · 4.001" × 3.484" · 10.5:1 | 350 ci | 4.001" × 3.484" | 10.5:1 | 275–285 |
| Pontiac 350ci · 4.001" × 3.484" · 9.9:1 | 350 ci | 4.001" × 3.484" | 9.9:1 | 275 |
| 350 2-bbl | 350 ci | 3.8" × 3.85" | — | 265 |
| 350 H.O. 4-bbl | 350 ci | 3.8" × 3.85" | — | 325 |
| L98 | 350 ci | 4.001" × 3.484" | — | 210–240 |
| LT1 | 350 ci | 4.001" × 3.484" | — | 285 |
| LT1 + WS6 Ram Air | 350 ci | 4.001" × 3.484" | — | 305 |
| Pontiac 350ci (1969) | 350 ci | 3.8" × 3.85" | — | 265–330 |
Both bore and stroke vary across the family, so these are separate castings rather than variations on one block.
Compression spans 8.301:1 to 10.75:1, so fuel requirements differ meaningfully between members — worth checking before assuming parts interchange.
7 of 13 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.