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Ford 250ci specs: 250 ci (4.1L) 6-cylinder, 3.682 x 3.91 in (93.5 x 99.3 mm) bore and stroke, 9.75:1 compression. Rated 72-99 hp, 1973–1975.
The Ford 250ci is undersquare — the 3.91" stroke exceeds the 3.682" bore by 5.8% — a layout that trades peak RPM for leverage and torque low in the range. The 3.91" stroke puts mean piston speed at 4,000 ft/min around 6,150 RPM, which is where a production bottom end is generally considered at its limit. A rod ratio of 1.504 is short — higher piston acceleration and more side-load, typical of stroker combinations and a reason to watch piston speed closely. Each of the 6 cylinders displaces 41.7 ci (683 cc).
9.75:1 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 6 engines in the Ford 250ci family, all of them 250 ci — the differences between them are in compression, heads and rating, not displacement. 4 factory variants share these dimensions, rated from 72 to 99 hp across 1973–1975.
| Displacement | 250 ci / 4.1 L |
|---|---|
| Bore | 3.682" |
| Stroke | 3.91" |
| Cylinders | 6 |
| Configuration | I6 |
| Compression ratio | 9.75:1 |
| Rod length | 5.88" |
| Rod ratio | 1.504 |
| Bore/stroke ratio | 0.942 |
| Piston deck clearance | 0.083" |
| Block material | cast iron |
|---|---|
| Head material | cast iron |
| Valvetrain | OHV |
| Fuel type | gas |
| Advertised HP | 72–99 hp |
| Years | 1973–1975 |
| Bore/stroke character | 0.942 — undersquare — stroke exceeds bore, which favours low-end torque |
|---|---|
| Mean piston speed at 6,000 RPM | 3,910 ft/min — in the range typical of performance street engines |
| Rod ratio | 1.504 — short — more side loading and piston dwell at TDC, typical of stroker combinations |
| Displacement per cylinder | 41.7 ci |
| Static compression | 9.75:1 — in the range that usually runs on pump premium |
| Intake valve diameter | 1.66" |
|---|---|
| Exhaust valve diameter | 1.399" |
| Chamber volume | 59.4 cc |
| Rocker ratio | 1.5:1 |
| Lifter type | hydraulic |
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 |
|---|---|---|
| 1973 | 88 hp | — |
| 1973 | 93 hp | — |
| 1973 | 99 hp | — |
| 1975 | 72 hp | — |