Oldsmobile 250ci Specs: 3.875 x 3.53 in

Oldsmobile 250ci specs: 3.875 x 3.53 in (98.4 x 89.7 mm) bore and stroke, shared by all 3 versions. Displacement, compression and factory ratings.

At a glance

Displacement	250 ci
Cylinders	6
Bore	3.875"
Stroke	3.530"
Compression	9.2:1
Advertised power	105–155 hp
Years	1966–1976
Cylinder head data	1 of 3 engines

Engines in this family

Engine	Displacement	Bore × Stroke	CR	HP
Oldsmobile 250ci (1976) · 105 hp	250 ci	3.875" × 3.53"	9.211:1	105
Oldsmobile 250ci (1966–1971)	250 ci	3.875" × 3.53"	—	145–155
L-6	250 ci	3.875" × 3.53"	—	155

Factory cars with a Oldsmobile 250ci

• Oldsmobile Cutlass: 1966, 155 hp; 1967, 155 hp; 1968, 155 hp; 1969, 155 hp; 1970, 155 hp; 1971, 145 hp

What varies across the family

All are oversquare — bore larger than stroke, which favours revs over low-end torque.

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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