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How to build a reliable, powerful Ford Y-block

HOT ROD logo HOT ROD 9/4/2018 Hot Rod Network Staff

What is it about Ford's first overhead valve V-8 and our fascination with this red-hot slice of classic American iron? You know it has to be the sound alone with 16 mechanical flat tappets and that soft throaty bark at the tailpipes that holds our attention. It is also the sound of a vintage Ford starter and that spring-loaded starter drive followed by the sound of a vintage Y-block that gets us fired up to build one.


It isn't what the Y-block is that excites us. It's what the Y-block isn't. It isn't a high-tech, late-model overhead cam engine or a direct-injected LS you can spin to 6,500 rpm without breaking a sweat. The Ford Y-block is a stodgy old cast-iron American V-8 that has taken a lot of research and development to produce respectable horsepower and torque at the Engine Masters Challenge.

The Ford Y-block V-8 was never intended to be a high-performance engine in the first place. Yet there are those like Ted Eaton, Jon Kaase, and John Mummert who have committed their lives to making the most of this distinctive postwar mill. Both Kaase and Eaton have taken Y-blocks to the Engine Masters Challenge and made in excess of 600 hp with specially prepared Ford Y-blocks. For our streetable Y-block mill we will settle for less, yet with plenty of low-end torque for a Saturday night cruise.

Ford introduced the 239ci Y-block in 1954 in Fords and a 256ci version in Mercurys to replace its flathead V-8 introduced more than two decades earlier in 1932. Ford quickly grew the Y-block to 272, 292, and finally 312 ci in most of the lineups by 1956. Though the Y-block was revolutionary when it was introduced, it was cursed with limitations right from the get-go, mostly in the area of displacement and cylinder head design. It was a limited engine in terms of growth, which means there's only so much you can do with this engine if you have a limited budget and resources. If you have the talent, resources, and capital, however, you can make real power with this engine.

Why build a Y-block based on what we've just told you? Because it's the right thing to do if you're building a classic Ford truck and want a real authentic sound and feel when you twist the key. Forget the 90-degree Fairlane V-8 known as the small-block Ford, and both the FE and 385-series big-blocks a lot of enthusiasts like to install in classic Ford trucks. If you're building a vintage Ford truck, the Y-block is the only mill that will do from an emotional standpoint. It just feels right.

We're building a stock 312ci Y-block. The downside to 312 blocks is they're rare because they were produced in very limited quantities. And because the 312 is the most desirable Y-block, they've been used up over time.

John Mummert of John Mummert Machine tells us block identification numbers are generally found on the side of block above the oil filter on blocks cast at Cleveland ("CF" logo). Blocks cast at the Dearborn iron foundry ("DIF" logo) have block identification numbers near the distributor in back or above the generator. Most Dearborn foundry blocks were used in trucks, yet no Dearborn Y-blocks were produced after 1957. There were no special Y-block truck blocks. Heavy-duty trucks with steel cranks used C1AE or C2AE blocks produced for both car and truck lines.

Nearly all Dearborn blocks cast after 1954 were 272s. Most 292 and 312 blocks were cast at the Cleveland foundry. It is generally accepted that no 312 blocks were produced at the Dearborn foundry. Mummert confirms 312 block casting numbers as ECZ-6015A, ECZ-6015B, ECZ-6015C, EDB-6015E,B9AE-6015F. Of these the ECZ-6015A and ECZ-6015C are the most common. He adds some 312 service replacement blocks are numbered C2AE-6015C. What's more, he tells us 312 main caps are always marked ECZ while all other Y-block main caps are marked EBU. He stresses this is the only positive way to identify a 312 block.

Although the 312 remains the most popular Y-block you can get by with a 272 or 292. John tells us nearly any 272, 292, or 312 block can be used for performance use with the right modifications. The 272 block can be bored the 292's bore dimensions. And since all other internal components are the same across the board this gives you a 292ci Y-block. He adds that 292 pistons are easier to find, cheaper, and have a better ring selection.

John goes on to say the 292 blocks from 1955-1964 are easier to find. In fact, improvements were made to 292 and 312 blocks in 1959 with deeper drilled main cap threads for strength. The 1961-1964 C1AE and C2AE blocks have additional material in the main webs for added strength. These blocks typically don't sonic check as thick as earlier blocks according to John. Therefore, he adds, if a good early block is found, drill and tap the main bearing cap threads deeper and use the early block.

On our workbench is a pair of ECZ-C cylinder heads for our build used across the board on the 272, 292, and 312. We opted for stainless steel valves and hardened exhaust valve seats for use with unleaded fuels. The most desirable Y-block heads for increased compression are the 1957 through early 1958 ECZ-G castings with intake valves sized at 1.927 inches, according to Mummert. Combustion chamber size is approximately 69cc. For slightly lower compression for today's pump gas is the 1958-1959 5752-113 casting. These heads have the same 1.927-inch intake valves and a slightly larger chamber, which lowers compression. For low-compression engines the 1959 5750-471 truck head is also a good choice, Mummert tells us, with a 1.927-inch intake valve and 80cc chamber. It is the same head casting as the "EDB" supercharger head, yet with a different casting number.

Mummert offers the following build tips for your Y-block build project:

  • Never throw away your old camshaft until you've saved the thrust spacer. The new cam will not come with one. If you've already thrown it away you're in luck because John Mummert may have some on hand.
  • There appear to be two different length head bolts in a Y-block—five short bolts near the spark plugs and five longer bolts under the rocker arm assemblies. The five short bolts near the spark plugs are identical but the five under the rocker arms are not the same. Two of these head bolts are slightly longer and installed at the outer ends of the cylinder head where alignment dowels are located. Lay all 10 long bolts (five per bank) next to each other and you should find four longer and six that are about 1/4-inch shorter. Installing the longer bolts in the center three holes can cause them to bottom in the block, which can result in a blown head gasket. Late production Y-block engines have only long and short bolts.
  • Both cylinder head gaskets are identical. It might seem that the same face of the gasket would go against the block and the opposite face would go against the head on each side. This is not true. What is critical is that the open coolant holes are located at the back of the head and the blocked portion of the gasket is at the front. Otherwise you will experience overheat. Look for the word "FRONT" on the gasket and place it at the front, even if it looks incorrect. This places one of the gaskets face up and one face down. Notice that there is a square corner at one end of each gasket. The square corner must be at the front of the engine. This can be checked without removing the heads. If you are having overheating problems check for these square corners at the top front corner of the head near the intake gasket.
  • If you're using a camshaft with a cross-drilled center journal you must use 1955 through early 1956 cam bearings designed for cross-drilled camshafts. If you are installing a cam with a grooved center journal you must use the late 1956-1964 cam bearings. If your cam will not fit in the block check it for trueness. Mummert has seen cams with up to 0.010-inch runout, which is not acceptable. Another issue seen is the front cam bearing installed cocked in the bore. Install the front bearing from the rear to ensure proper alignment.
  • Mummert stresses installing rocker arm shafts right side up. Rocker shaft stands are identical and will bolt down either way. However, the oil hole in the shaft must align with the hole in the shaft stand and is at the bottom when the stands are bolted down. Get this wrong and you starve the rockers of oil and wind up with valvetrain failure and engine damage.
  • When Ford designed the 312 it made the main caps taller than the 292 cap, anticipating greater loads. However, the 312 rear main cap is at the 292's height to clear the rear main seal holder and the oil pan rail. This makes it possible to install any of the longer main cap bolts in error from the first four main caps in the rear cap where they could bottom out. Some blocks are drilled deep enough to accept the longer bolts in the rear cap. This is not acceptable. There have been a few instances where the rear main saddle of a 312 cracked during assembly due to incorrect bolt usage.
  • Another problem has long been the incorrect torque specification of 120 ft-lb main cap bolt torque, which was printed in all 1956 factory and many repair manuals. This figure is excessive and has undoubtedly caused many of the cracked main webs in 312 blocks. Always torque main cap bolts to 95 ft-lbs. It is also critical to check the amount of thread that will be engaged in the block. Do not use main cap bolts in any Y-block that don't reveal at least 7/8 inch of thread when placed in the main cap. This may require running a bottoming tap into the main bolt holes.Later 292 engines have significantly longer main cap bolts, an indication that Ford realized this need. Care must be used not to use bolts or studs that engage more than 1 1/8-inches of thread because the oil passage to the main bearing will be blocked.
  • Be sure not to use excessive-length bolts for the intake manifold. The intake manifold bolt holes in the head intersect push rod passages and too long a bolt can hit the push rods. Also be certain that the bolt holes in the heads at the rear of the manifold are plugged. These are the threaded holes that are unused but are drilled through into the push rod passage. Water, dirt, and other crud can enter the engine through these holes. Be sure to use short bolts, about 1/2 inch of thread so you don't hit the push rods.
  • Check the 5/16-inch-diameter timing cover bolt length. If these bolts are too long they can contact the front cylinders doing extensive damage. Apply sealer to bolts that enter the water jackets. They are the two bolts above and below the water passages with four total.
  • Though all Y-block cylinder heads can be installed on either side of the block, after years of exposure to coolant the 0.906-inch holes at the front of the intake surface will not accept a freeze plug. When choosing heads be sure you have a usable left and right. And when installing heads be sure the corroded 0.906-inch hole is located toward the front of the engine. Be sure the hole at the rear of the head will accept a freeze plug or a temperature sender bushing. The corroded hole can be reamed to a larger size and an oversize plug installed. It is very discouraging to have two heads ready to install and find that they cannot be used as a set.
  • Remove all oil galley plugs and the oil filter adapter before having your block cleaned. John tells us he's had the best luck by drilling out the center of the oil plug, leaving the hex. He adds after carefully heating the plugs with a torch they come right out.
  • Always have the block decks surfaced, main bearing bores align honed, and head decks surfaced. These castings distort after years of operation and heat-cycling.
  • Although most modern cylinder head gaskets are billed as not needing to be re-torqued always re-torque your cylinder heads. This should be done 500-750 miles after assembly.
  • Some people try to align the timing marks on the gears toward each other as is common on newer engines. This is bound to happen often because the replacement timing sets no longer have the pins marked for correct alignment with the gears. The marks on the Y-block timing gears aim toward the oil filter side with 12 pins between them. Please keep this in mind.
  • It appears that Ford used two different thrust washer thicknesses and cam plates. With the wrong combination there will be no camshaft endplay and failure is certain. Ensure at least 0.004-inch camplay endplay during assembly.
  • Replacement camshaft cores have a glob of metal between the last lobe and the distributor gear. On high lift cams this glob can be higher than the base circle of the lobe, which can do damage. Place a lifter on the last lobe base circle and be sure the lifter clears this excess material. These affected cam cores appeared around 2001-2003 and it is likely they're out of the system.

Building a Y-block isn't for the faint of heart because you have to be resourceful and know where to find parts and service. It is a numbers game because these engines have been out of production for more than 50 years. You're going to need to source all of the castings or a complete unmolested engine in need of a little love. For a peaceful, fun-loving street engine you can build quite the 292- or 312ci Y-block and have plenty of power for the cruise. And torque is the kind of power you want on the street.

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