Bore, stroke, displacement and compression for all 23 GMC Small Block Chevy engines, compared side by side. Plus rod ratio and head specs where published.
| Displacement | 265–400 ci |
|---|---|
| Cylinders | 8 |
| Bore | 3.750–4.125" |
| Stroke | 3.000–3.760" |
| Compression | 8.0–11.0:1 |
| Advertised power | 119–290 hp |
| Years | 1955–1998 |
| Cylinder head data | 2 of 23 engines |
| Engine | Displacement | Bore × Stroke | CR | HP |
|---|---|---|---|---|
| 400 | 400 ci | 4.1248" × 3.7598" | 8:1 | 150 |
| 350 | 350 ci | 4" × 3.4799" | 9:1 | 160 |
| 327 | 327 ci | 4" × 3.25" | 10.5:1 | 250 |
| 307 | 307 ci | 3.8748" × 3.25" | 9:1 | 200 |
| 305 | 305 ci | 3.75" × 3.4799" | 8.5:1 | 130 |
| LG9 | 305 ci | 3.75" × 3.4799" | — | 130–140 |
| LE9 | 305 ci | 3.75" × 3.4799" | — | 160 |
| LF3 | 305 ci | 3.75" × 3.4799" | — | 155 |
| L03 | 305 ci | 3.75" × 3.4799" | — | 170–175 |
| L30 | 305 ci | 3.75" × 3.4799" | — | — |
| 302 | 302 ci | 4" × 3" | 11:1 | 290 |
| 283 | 283 ci | 3.8748" × 3" | 8.5:1 | 185 |
| 265 | 265 ci | 3.75" × 3" | 8:1 | 162 |
| Small Block Chevy (1956–1981) | 265 ci | 3.75" × 3" | — | 119–210 |
| Turbo-Fire V8, 2-bbl | 265 ci | 3.75" × 3" | — | 162 |
| Power Pack | 265 ci | 3.75" × 3" | — | 180–205 |
| Turbo-Fire 2-bbl | 265 ci | 3.75" × 3" | — | 162–170 |
| RPO 411 | 265 ci | 3.75" × 3" | — | 225 |
| Turbo-Fire 265 2-bbl | 265 ci | 3.75" × 3" | — | 162 |
| V8 | 265 ci | 3.75" × 3" | — | 195 |
| 469 | 265 ci | 3.75" × 3" | — | 225 |
| 469 + 449 | 265 ci | 3.75" × 3" | — | 240 |
| LS5 | 265 ci | 3.75" × 3" | — | 120 |
Both bore and stroke vary across the family, so these are separate castings rather than variations on one block.
Compression spans 8:1 to 11:1, 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.