Pontiac 428ci specs: 4.125 x 4.00 in (104.8 x 101.6 mm) bore and stroke, shared by all 4 versions. Displacement, compression and factory ratings.
| Displacement | 428 ci |
|---|---|
| Cylinders | 8 |
| Bore | 4.125" |
| Stroke | 4.000" |
| Compression | 10.5–10.8:1 |
| Advertised power | 360–390 hp |
| Years | 1967–1969 |
| Engine | Displacement | Bore × Stroke | CR | HP |
|---|---|---|---|---|
| Pontiac 428ci (1967) · 360 hp | 428 ci | 4.125" × 4" | 10.501:1 | 360 |
| Pontiac 428ci (1967) · 376 hp | 428 ci | 4.125" × 4" | 10.751:1 | 376 |
| Pontiac 428ci (1968–1969) | 428 ci | 4.125" × 4" | — | 370–375 |
| 428 H.O. | 428 ci | 4.125" × 4" | — | 390 |
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.