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Cadillac 390 Series (1959–1963) specs: 390 ci (6.4L) 8-cylinder, 4.00 x 3.874 in (101.6 x 98.4 mm) bore and stroke, 10.5:1 compression. Rated 325-345 hp.
The Cadillac 390 Series (1959–1963) is close to square: 4" bore against 3.874" stroke, within 3.3%, which splits the difference between a high-revving layout and a torque layout. The 3.874" stroke puts mean piston speed at 4,000 ft/min around 6,200 RPM, which is where a production bottom end is generally considered at its limit. Each of the 8 cylinders displaces 48.8 ci (799 cc).
10.5:1 on iron heads is in the range that usually runs on pump premium; iron holds heat, so treat it as the less forgiving side of that range.
It is one of 2 engines in the 390 Series family, all of them 390 ci — the differences between them are in compression, heads and rating, not displacement. 7 factory variants share these dimensions, rated from 325 to 345 hp across 1959–1963.
| Displacement | 390 ci / 6.4 L |
|---|---|
| Bore | 4" |
| Stroke | 3.874" |
| Cylinders | 8 |
| Configuration | V8 |
| Compression ratio | 10.5:1 |
| Bore/stroke ratio | 1.033 |
| Block material | cast iron |
|---|---|
| Head material | cast iron |
| Valvetrain | OHV |
| Fuel type | gas |
| Firing order | 1-5-6-3-4-2-7-8 |
| Advertised HP | 325–345 hp |
| Years | 1959–1963 |
| Year | Version | HP @ rpm | Torque @ rpm | Comp. | Duration int / exh | Valve lift int / exh | LSA |
|---|---|---|---|---|---|---|---|
| 1959 | gross | 325 @ 4800 | 430 lb-ft @ 3100 | 10.5:1 | 324° | 0.451" | 113° |
| 1959 | gross | 345 @ 4800 | 435 lb-ft @ 3400 | 10.5:1 | 324° | 0.451" | 113° |
| 1960 | gross | 325 @ 4800 | 430 lb-ft @ 3100 | 10.5:1 | — | — | — |
| 1960 | gross | 345 @ 4800 | 435 lb-ft @ 3400 | 10.5:1 | 282° | 0.450" | 113° |
| 1961 | gross | 325 @ 4800 | 430 lb-ft @ 3100 | 10.5:1 | — | — | — |
| 1962 | gross | 325 @ 4800 | 430 lb-ft @ 3100 | 10.5:1 | — | — | — |
| 1963 | gross | 325 @ 4800 | 430 lb-ft @ 3100 | 10.5:1 | 324° | 0.451" | 113° |
Factory specification sheet. Durations are the factory's advertised figures at the basis printed on the sheet, not duration at .050" lift; lobe separation is calculated from the printed valve timing.
| Bore/stroke character | 1.033 — square — bore and stroke are within 5%, a balanced compromise |
|---|---|
| Mean piston speed at 6,000 RPM | 3,874 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 48.8 ci |
| Static compression | 10.5:1 — in the range that usually runs on pump premium |
Each link opens the calculator with this engine's specs already filled in.
These records share identical bore, stroke, displacement and compression. They differ by model year and factory power rating.
| Year | Advertised HP | Code |
|---|---|---|
| 1959 | 325 hp | — |
| 1959 | 345 hp | — |
| 1960 | 325 hp | — |
| 1960 | 345 hp | — |
| 1961 | 325 hp | — |
| 1962 | 325 hp | — |
| 1963 | 325 hp | — |
2 factory vehicles, 1959–1963. Each year opens that model's engine table.