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Ford Model A 201 four specs: 200.5 ci (3.3L) 4-cylinder, 3.875 x 4.25 in (98.4 x 108 mm) bore and stroke. Rated 40 hp, 1928–1931.
The Ford Model A 201 four is undersquare — the 4.25" stroke exceeds the 3.875" bore by 8.8% — a layout that trades peak RPM for leverage and torque low in the range. The 4.25" stroke puts mean piston speed at 4,000 ft/min around 5,650 RPM, which is where a production bottom end is generally considered at its limit. Each of the 4 cylinders displaces 50.1 ci (821 cc).
It is one of 3 engines in the Model A/B Four family, all of them 200.5 ci — the differences between them are in compression, heads and rating, not displacement. 4 factory variants share these dimensions, rated at 40 hp across 1928–1931.
| Displacement | 200.5 ci / 3.3 L |
|---|---|
| Bore | 3.875" |
| Stroke | 4.25" |
| Cylinders | 4 |
| Configuration | I4 |
| Bore/stroke ratio | 0.912 |
| Block material | cast iron |
|---|---|
| Head material | cast iron |
| Valvetrain | flathead |
| Fuel type | gas |
| Firing order | 1-2-4-3 |
| Advertised HP | 40 hp |
| Years | 1928–1931 |
| Bore/stroke character | 0.912 — undersquare — stroke exceeds bore, which favours low-end torque |
|---|---|
| Mean piston speed at 6,000 RPM | 4,250 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 50.1 ci |
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These records share identical bore, stroke, displacement and compression. They differ by model year and factory power rating.
| Year | Advertised HP | Code |
|---|---|---|
| 1928 | 40 hp | Model A 201 four |
| 1929 | 40 hp | Model A 201 four |
| 1930 | 40 hp | Model A 201 four |
| 1931 | 40 hp | Model A 201 four |