Story and Photography by John Mummert
The Ford Y-Block was introduced in 1954 to replace the well-know flathead. Displacement was unchanged at 239 cu. in., but the new engine had five main bearings, five cam bearings and overhead valves. Bore was 3.500" and stroke was 3.100" with 6.324" connecting rods. Model year 1954 Mercury vehicles had a 256 cu. in. version with 3.625" bore and 3.100" stroke. Displacement was increased in 1955 to 272 cu. in. for most Ford car production. T-Bird and Mercury models got a 292 cu. in. version. The added displacement was achieved with a 3.625" bore and 3.300" stroke for the 272 and 3.750" bore and the same 3.300" stroke. The 3.100" crankshaft is marked EBU, while the 3.300" crankshaft is marked EC.
In 1956, a 312 cu. in. version was introduced and installed in all Mercury models, and as an option in 1956 T-Birds and some high-line Ford models. The 312 had a 3.800" bore and 3.440" stroke with a shorter 6.254" connecting rod. The block, crankshaft and connecting rods all have the ECZ identifier denoting special 312 parts. Although all Y-Blocks use the same connecting rod bearing with 2.188" rod journal, the main bearing size was increased from 2.498" on the EBU and EC crankshafts to 2.625" for the ECZ 312 crankshaft. What this means is that a 239 crankshaft will fit in a 272 or 292 block, and vice-versa, but the 312 crankshaft will not fit in the smaller blocks. This can be remedied by grinding the main bearing journals of a 312 crankshaft to 2.498", but the cast in oil slinger and rear main seal surface will also need to be reduced. You must use 6.254" connecting rods with this combination and 312 pistons due to reduced skirt length. Two foundries were used to cast blocks and heads from 1954-1957. This makes identifying Y-Block parts more difficult because different locations were used for casting numbers. The letters DIF cast near the distributor identify parts cast at the Dearborn Industrial Foundry. A three-digit casting number will be found nearby, typically EBU or ECG. As stated, EBU is a 239 while ECG indicates a 272. Most Dearborn blocks found today are ECG. The full casting number of ECG6015 will be found on the side of the block near the generator. Please note that 6015 indicates that the part is an engine block so all blocks have this number in the sequence. Cleveland Foundry parts have an F surrounded by a semicircle to identify their source. The Cleveland foundry cast the larger 292 and 312 blocks, and the casting number can be found above the oil filter. Although rare, there were a few 1957 292s cast at the Dearborn foundry with EDB6015 near the generator. Equally rare are 1957 272s cast at Cleveland with ECG6015 cast above the oil filter. Since 312s were machined from the same block casting as a 292, they are nearly impossible to identify externally. Any casting number used on 312 blocks was also used on 292 blocks. Although most 312s were ECZ6015 followed by A, B or C, these can also be a 292. The best way to identify a 312 externally is by checking the flywheel flange on the crankshaft. The 312 ECZ crankshaft has an aspirin-sized dot on the outer edge. If the engine is disassembled, check the casting number on the main cap. ECZ is cast into 312 main caps; all others are EBU. Cylinder head casting numbers can be found under the valve cover on early heads, between the exhaust ports on some heads or under the water passage to the intake manifold. Regardless of the source, the external dimensions of all Ford Y-Blocks are the same. Any year exhaust manifold will bolt to any year head. Flywheels and bellhousings are interchangeable, along with timing covers and crankshaft dampers. There are some parts specific to the 1954 EBU 239 engines. These include the fuel pump, water pump, oil pump, distributor, cam bearings and camshaft. From 1955 until the end of production in 1964, parts can be easily interchanged. Y-Block production at the Dearborn foundry ended after the 1957 model year with the introduction of the new FE and MEL series of engines. Production continued at the Cleveland foundry while the Y-Block was installed in cars through 1962 and trucks through 1964. Y-Blocks were also used for industrial power plants and converted for marine use by Dearborn Marine.
The ECZ-G cast-in designation identifies cylinder heads used on 272 CID 1957 2-bbl pickups, 292 CID 1957 2-bbl T-Birds and other Ford cars, 312 CID 1957 Ford, Mercury and T-Bird 4-bbl, 312 CID 1957 Ford and T-Bird 4bbl engines, 292 CID 1958 early production 2-bbl Fords and pickups, and 312 CID 1958 4-bbl Mercury.
An easy way to identify a 312 CID crankshaft is by the aspirin-sized dot on the flywheel flange.