Ford Model A/B Four Specs: 3.875 x 4.25 in

Ford Model A/B Four specs: 3.875 x 4.25 in (98.4 x 108 mm) bore and stroke, shared by all 3 versions. Displacement, compression and factory ratings.

At a glance

Displacement	200.5 ci
Cylinders	4
Bore	3.875"
Stroke	4.250"
Advertised power	40–50 hp
Years	1928–1934

Engines in this family

Engine	Displacement	Bore × Stroke	CR	HP
Model A four	200.5 ci	3.875" × 4.25"	—	—
Model A 201 four	200.5 ci	3.875" × 4.25"	—	40
Model B four	200.5 ci	3.875" × 4.25"	—	50

Factory cars with a Model A/B Four

• Ford Model A to Model 40: 1928, 40 hp; 1929, 40 hp; 1930, 40 hp; 1931, 40 hp; 1932, 50 hp; 1933, 50 hp; 1934, 50 hp

What varies across the family

All are undersquare — stroke larger than bore, favouring torque low in the range.

Each engine page carries rod ratio, mean piston speed, bore/stroke character and cylinder head specs where published, and links into the calculators with its dimensions already filled in.

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