gap measure for this problem by feeding oil via an external tube directly to the rocker shafts from the main oil gallery. Cylinder heads on the Y-Block have always been a point for discussion. Because of the configuration of the intake ports, vertically in pairs instead of horizontally side by side, and the way in which they make sharp turns around the head bolts, they have been called “bad breathers”. Although their flow can indeed be inferior, they are nonetheless able to rev to 7,000+ rpm. Ford Y-blocks are easily identified. The distributor is located at the back of the engine and off to one side and the valve covers are held on with two bolts through the top. 239 The first Y-block on Ford automobiles and F100 trucks was the 239 in³ (3,910 cc) version as released in 1954 with EBU casting numbers. The Y-block was the same displacement as the old Ford Flathead V8 that it replaced but with a bigger bore and a shorter stroke (3.5 x 3.1 in). It produced 130 bhp (97 kW) at 4,200 rpm as opposed to the flathead's final 110 bhp (82 kW) at 3,800 rpm, an increase of 18%. Torque was also up compared to the Flathead, with 214 lb·ft (290 N·m) at 1,800rpm compared with 196 lb·ft (266 N·m) at 2,000rpm. The Y-block was considered a major advancement over the flathead. The 239 in³ version was available in 1954 models (EBU casting numbers), and in late 1954 and 1955 (EBV casting numbers), while also in 1955 the bigger 272 in³ and 292 in³ siblings were introduced. The 1955 EBV 239 engine exchanges many parts with later model Y-blocks such as the 272 and 292, while the 1954 EBU engine has many parts that do not exchange with the 1955 EBV 239 and later Y-blocks. 256 The original Mercury Y-block, introduced for the 1954 model year, displaced 256 in³ (4,194 cc). Advertised as the "V-161" engine, it ran a bore and stroke of 3.625 x 3.1 in. The compression ratio was 7.5:1, and the rated power was at 4,400 rpm. Torque was at 2,200 rpm. The engine breathed through a Holley model 2140 (4V) carburetor. The 256 in³ version of the Mercury Y-block was only available in 1954 models and was replaced by the 292 in³ in 1955. The 256 was also used in some F100s in 1955 depending on the