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Mercury Windsor (1963–1964) specs: 260 ci (4.2L) 8-cylinder, 3.799 x 2.87 in (96.5 x 72.9 mm) bore and stroke. Rated 164 hp, 1963–1964.
The Mercury Windsor (1963–1964) is oversquare — the 3.7992" bore exceeds the 2.8701" stroke by 32.4% — a layout that favors airflow and RPM over leverage at the crank. The 2.8701" stroke does not reach 4,000 ft/min of mean piston speed until about 8,350 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 8 cylinders displaces 32.5 ci (533 cc).
It is one of 18 engines in the Windsor family, sitting between the 221 ci and 351 ci members. 2 factory variants share these dimensions, rated at 164 hp across 1963–1964.
| Displacement | 260 ci / 4.2 L |
|---|---|
| Bore | 3.7992" |
| Stroke | 2.8701" |
| Cylinders | 8 |
| Configuration | V8 |
| Compression ratio | 8.7–8.8:1 (published figures vary) |
| Bore/stroke ratio | 1.324 |
| Block material | cast iron |
|---|---|
| Head material | cast iron |
| Valvetrain | OHV |
| Fuel type | gas |
| Advertised HP | 164 hp |
| Years | 1963–1964 |
| Year | Version | HP @ rpm | Torque @ rpm | Comp. |
|---|---|---|---|---|
| 1963 | gross | 164 @ 4400 | 258 lb-ft @ 2200 | 8.7:1 |
| 1964 | EEY gross | 164 @ 4400 | 258 lb-ft @ 2200 | 8.8:1 |
Factory specification sheet.
| Bore/stroke character | 1.324 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 2,870 ft/min — conservative for a street engine |
| Displacement per cylinder | 32.5 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 |
|---|---|---|
| 1963 | 164 hp | — |
| 1964 | 164 hp | — |
1 factory vehicle, 1963–1964. Each year opens that model's engine table.