256
The original Mercury Y-block, introduced for the 1954 model year, displaced 256 in³ (4.2 L). Advertised as the "V-161" engine, it ran a bore and stroke of 3-5/8" X 3-3/32". The compression ratio was 7.5:1, and the rated power was 161 hp (120 kW) at 4400 rpm. Torque was 238 lb·ft (323 N·m) at 2200 rpm. The engine breathed through a Holley model 2140 (4V) carburetor.
Read more about this topic: Ford Y-block Engine