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Ever Wondered “Y”

Going inside Ford’s first overhead valve V-8

Jim Smart - November 29, 2012 10:00 AM

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As its nickname implies, the Y-block is a skirted block design with plenty of down under support. This is the ’57 312 block (ECZ-6015-B).

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The Y-block has an aluminum rear main seal cap, which is separate from the #5 main cap. This cap has two side seals and half the rear main seal.

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John Mummert tells us the Y-block’s bottom end is straightforward with three different strokes — 3.10-, 3.30-, and 3.44-inches across four bore sizes. This is the 312’s crank and reciprocating mass with a 3.44-inch stroke. What makes the 312’s crank different aside from stroke is main bearing journal size, which is larger. Rod journal size is the same across the board.

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With the exception of the 312 and 292 heavy-duty truck engines, which have 6.252-inch rods, all Y-blocks have 6.324-inch forged connecting rods. These are fitted with ARP 3/8-inch bolts. We’re told the best rods to use are the 1962-’64 C2AE rod or the 1961-’64 C1TE truck rod.

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All Y-blocks used free-floating and bushed piston pins.

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The Y-block’s unique stacked intake ports look like this. Y-block heads are right and left specific. Make sure you don’t wind up with two rights or two lefts or install them on the wrong sides.

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Stacked Y-block heads are brought up to current specifications with bronze guides and hardened exhaust valve seats, which buy them new life.

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Heads and block are decked for trueness. John Mummert tells us if you use a composition head gasket, you could lose as much as 12 percent of your compression. He also stresses not milling some head castings any more than .025-inch and find out if the heads have been milled previously. Plan to sonic check your castings where possible before machine work.

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JGM Performance Engineering has reconditioned these 312 heads with new stainless steel valves, hardened exhaust seats, and bronze guides. It is suggested you do a mock-up before final assembly, checking pre-assembly dimensions including compression height. Check combustion chamber volume while you’re at it to determine compression ratio prior to final assembly.

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The Y-block has conventional old-fashioned tappets that install from underneath prior to camshaft installation.

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Engine assembly lube is used on cam journals. Moly coat is used on lobes and tappets only for break-in and work hardening. John Mummert stresses not to forget the cam thrust spacer, which is easy to overlook when you toss the old cam.

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Timing cover is old school cast iron and weighs 16 pounds.

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John Mummert tells us you could lose as much as 12 percent of your Y-block’s compression with a composition head gasket. This is why a mock-up is important prior to final assembly. Cooling passages go at the back of the block.

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Y-block oil pumps are external and cam-driven with a pick-up tube outside of the oil pan. Use Permatex’s The Right Stuff on the pick-up gasket and do not overtighten. Make sure there’s at least ¼-inch between pick-up and pan.

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As with corporate cousin FE big-blocks, the Y-block’s valvetrain is shaft-mounted with adjustable cast rocker arms. It is easy to install rocker arm shafts upside down, so be careful. The oil hole in the shaft must line up with the pedestal stand or you will have dry rocker arms. John Mummert suggests the “ECG” 1.54:1 ratio rocker arms (1956-’57).

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“The best way to check for proper assembly is to look for the holes for the overflow tubes at the right hand end of each shaft. If the hole is visible with the rocker arms installed on the head it is correct,” John Mummert suggests.

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What is it about the Y-Block Ford engine that continues to get our attention?

Perhaps it’s that soft series of exhaust pulses and the gentle chatter of those shaft-mounted rocker arms thrashing out a beat in rhythm with its true flat-tappet cam. We’ve all heard the Y-block in some form or another since its introduction in 1954 as the 239ci in Fords and 256ci in Mercurys.

Ford’s Y-block V-8 really isn’t the company’s first overhead valve V-8. The larger displacement 317ci Lincoln Y-block was introduced in 1952 as a flathead replacement. What we like most about the Y-block and its larger cousin, the Lincoln Y-block, is its demeanor as a classic all-American V-8 engine. It is surely one of the best looking and sounding V-8s ever made in America.

John Mummert’s website (www.ford-y-block.com) is an incredible treasure trove of Ford Y-block information if you’re into vintage Ford V-8s. We can say with confidence no one knows more about Ford Y-blocks than Mummert, who has a lifetime of experience building these engines. We’re going to impart some of that wisdom to you here.

The Y-block is an interesting study because it incorporates nuances rarely seen anywhere else, like toadstool tappets you install through the bottom before cam installation and stacked intake ports that could be considered opposition to Chevrolet’s side-by-sides. It also utilizes a huge 16-pound cast iron timing cover and a precision-fit aluminum rear main seal cap. There’s an external oil pump and pipe style pick-up. Its flattop pistons are the size of trash cans, and if you know anything about the FE Series 332/352 big-blocks that arrived in 1958, you know the FE copped a number of Y-block design features, including its skirted Y-block persona and shaft-mounted rocker arms.

Because skirted blocks were heavier, Ford eliminated them when it conceived the 90-degree small-block and 385-series V-8s in the 1960s. Yet eliminating skirted blocks also meant sacrificing strength. Look at Ford today with its skirted block modular and Coyote overhead cam V-8s. Skirted blocks are back in style for their indestructible demeanor and smoothness, which is one reason why Y-blocks remain great desirable V-8s a half-century later.

Where the Y-block tends to fall short is power-making potential, though a few have been successful at it. Ted Eaton of Eaton Balancing has managed to get 540 horsepower and win the Engine Masters Challenge, but not without a lot of effort and raw talent. It was done with the new aluminum Y-block heads from John Mummert.

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