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Cadillac LF9 specs: 350 ci (5.7L) 8-cylinder, 4.057 x 3.385 in (103 x 86 mm) bore and stroke. Rated 105-125 hp, 1978–1985. Used in the Cadillac Seville.
The Cadillac 350ci (LF9) is oversquare — the 4.057" bore exceeds the 3.385" stroke by 19.9% — a layout that favors airflow and RPM over leverage at the crank. The 3.385" stroke does not reach 4,000 ft/min of mean piston speed until about 7,100 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 8 cylinders displaces 43.8 ci (717 cc).
It is one of 4 engines in the Cadillac 350ci family, all of them 350 ci — the differences between them are in compression, heads and rating, not displacement. 9 factory variants share these dimensions, rated from 105 to 125 hp across 1978–1985.
| Displacement | 350 ci / 5.7 L |
|---|---|
| Bore | 4.057" |
| Stroke | 3.385" |
| Cylinders | 8 |
| Configuration | V8 |
| Compression ratio | 22.1–22.5:1 (published figures vary) |
| Bore/stroke ratio | 1.199 |
| Fuel type | diesel |
|---|---|
| Firing order | 1-8-4-3-6-5-7-2 |
| Advertised HP | 105–125 hp |
| Years | 1978–1985 |
| Year | Version | HP @ rpm | Torque @ rpm | Comp. | Duration int / exh | Valve lift int / exh | LSA |
|---|---|---|---|---|---|---|---|
| 1980 | LF9 net | 105 @ 3200 | 205 lb-ft @ 1600 | 22.5:1 | 234° / 261° | 0.375" / 0.376" | 107.25° |
| 1981 | LF9 net | 105 @ 3200 | 200 lb-ft @ 1600 | 22.5:1 | — | — | — |
| 1982 | LF9 net | 105 @ 3200 | 200 lb-ft @ 1600 | 22.5:1 | — | — | — |
| 1983 | LF9 net | 105 @ 3200 | 200 lb-ft @ 1600 | 22.1:1 | — | — | — |
| 1984 | LF9 net | 105 @ 3200 | 200 lb-ft @ 1600 | 22.1:1 | — | — | — |
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 | 1.199 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,385 ft/min — conservative for a street engine |
| Displacement per cylinder | 43.8 ci |
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 |
|---|---|---|
| 1978 | — | LF9 |
| 1979 | — | LF9 |
| 1979 | 125 hp | LF9 |
| 1980 | 105 hp | LF9 |
| 1981 | 105 hp | LF9 |
| 1982 | 105 hp | LF9 |
| 1983 | 105 hp | LF9 |
| 1984 | 105 hp | LF9 |
| 1985 | 105 hp | LF9 |
21 factory vehicles, 1978–1985. Each year opens that model's engine table.