Wednesday, July 11, 2007

Y-block Ford and Mercury History

Ford Motor Co. introduced the Y-block overhead valve engines in 1954 to replace what had become over the preceding 22 years the hot rod world's most popular engine: the flathead V8. The Y-block only stayed in production as a passenger car engine for a mere eight years.

Here is probably the best historical introduction to the Y-block from the February, 1954, "Hot Rod" magazine:

Young Henry's New Engines ... Ford Forsakes the Flatheads

By Don MacDonald – Detroit Editor
"EDITOR’S NOTE: The hood’s up on the 1954 Ford and Merc. It’s all new under there from oil pan to rocker covers. We think you’ll like what you see and we’ll show you a simple way to make it even better.

When Detroit designs a new engine, you can count on the first production version hiding a development potential intended to be spread out over the next ten years. The reason, of course, is to ease the pain of paying for the tooling. Ford realized that jigs and dies for the old L-head V8 were wearing thin as far back as 1947. After 640 hand-built experimental units, a quarter –million hours of dynamometer testing, and more than four million miles of road testing, they’ve come up with a whole family of new engines.

This was no small project. You’re familiar with the four basic passenger car mills, or will be after you read this. But did you know that Ford builds five different truck engines, a four-cylinder tractor unit, and a line of industrial powerplants ranging from 134 to 317 cubic inches? Again, because of economics, each of these had to be a first cousin to the other. Similarity pays off through low tooling and production costs, but complicates the designer’s problem. He can’t just specify the Lincoln engine complete for the biggest Ford truck, although he must use the same basic block for this entirely different service requirement.

In addition to versatility, the whole family had to have what engineers call a “high futurity.” In other words, these engines had to be good for ten or more years of progressive increase in output per cubic-inch displacement. Even a member of the “big three” can’t afford to change an engine design every odd year. This means that compression ratios on Henry’s new powerplants can and will be raised just as fast as refiners come up with higher octane regular (not premium) gasolines. That fact alone tells why Ford and most other manufacturers have gone to overhead valve V8’s. This design, whether hemispherical or Ricardo, affords compact combustion chambers, relatively simple manifolding, and better breathing. Detroit is after a certified 12 to 1 ten years from now.

Still following the design philosophy behind Henry’s engines, higher output means higher bearing loads. So we find that all of them, even the in-line six, are short-stroked. This is the only way to get the compact crankshaft necessary for a structure rigid enough now to withstand the bearing loads of the future. Over-square engines offer other advantages; there’s less friction and more usable power, and the large bore makes room for larger valves.
Overly simplified, these are the principles which guided Ford engineers. They know that some of us will wangle maximum output from their design less than a year after buying one. It’s tough for them to hold back and dole out improvements over a ten-year period, but it’s economical. Let’s see what we have to start with.

The new Ford V8 engine is built around a block of exceptional strength. The central section extends well below the crankshaft centerline, giving 240 degrees of support to the five main bearings. Last year’s supported three mains at the centerline. The casting is flared between the main bearing supports and the corresponding five supports for the camshaft bearings. Cylinder head bolt bosses are located only on the outside walls of the water jacket. There are no interconnecting webs to distort the bores. Rigidity is further enhanced by the widely flared attachment for the bell housing and drive train. Do you remember, on the old engine, how the flywheel extended well beyond the narrow lower block structure? The only really strong connections between block and drive components were above the flywheel. Now there are four, all outside the flywheel and two of them are three inches below its center.

The new oil pan will give you a little trouble if you try to put this engine in a pre-1954 chassis. Ford and Mercury have changed over to ball-stud front suspension, so with the old front crossmember no longer in the way, they moved the deep part of the pan forward along with the oil inlet. This change also applies to the six. But you’ll like the wide, flat mating surface of the pan and the simple one-piece gasket. Engine mounts have been changed too – for a rather startling reason. Laboratory measurements show that you’ve been driving your Ford all these years without ever knowing that the engine sagged a sixteenth of an inch between front and rear supports. So they moved the front mount close to the longitudinal center of gravity. With the wide-base bell housing attachment, the tendency to sag is now negligible.

You won’t recognize the new piston and rod except that the former is still aluminum and has steel embedded struts. Only three rings this year, all above the piston pin, and the oil control has a factory-installed expander beneath the ring. The larger bore permits adoption of separate rod bolts with Lincoln’s easy-to-work-on cam head and eccentric hole. The rod structure isn’t weakened by notching it for the commonly used T-headed bolt. Main bearings are steel-backed copper-lead – fancy words for a really thin shell. Think back to the first Ford inserts in ’36 that were .020 of an inch thick. The new ones are less than .002 of an inch. Bearings went on a diet when engineers found that fat ones were prone to fatigue failures caused by continuous deformation of the soft babbitt.

The new crankshaft is interesting, not so much because of its five mains but because it is cast rather than forged. Precision molded of alloy iron, it has eight counterweights. You have to get above 4800 rpm before running into 4th-order power-impulse harmonics, so they left off the vibration dampener. Last year’s crank was pounding away at 4500, as you may have noticed. Having driven this new engine, we can vouch that the “Ford sound” is gone. The rigid, well-balanced crank is one of the reasons.

Another innovation is the new valve train, driven by a one-inch wide timing chain. But before getting into this, we should mention that the fuel pump is operated by an eccentric on the front of the camshaft sprocket. This, believe it or not, is carefully counterweighted, so watch it when you yank the factory version and install electric pumps. You’re already out of balance! Now to the valves. This is one rig that’ll give you 5000 rpm without bounce, although you’ll have to take some weight off the 30-pound flywheel to get there. The reason is low inertia stemming from good detail design. Shot-blasted valve springs have dampening coils at their lower ends. Rocker arms are precision-molded (cast) rather than forged. Cam acceleration patterns (for all Lincoln engines) are based on the results of a special research project involving Wayne University’s mechanical differential analyzer and Ford’s analog computer. It’s beyond us how these machines work, but we do know that they solve in minutes differential equations of motion that take human mathematicians months of effort.

An unusual feature of the new engines is integral valve guides. We’ve often wondered why people bother to sink separate guides into a block or head. They wear out and are hard to replace. They complicate and, in fact, prevent adequate heat transfer. If not installed properly, they distort or extend into the manifold passages to interfere with proper breathing. The oil-retaining cast iron of a block or head is a better bearing surface for hard-steel valve stems than any thin insert. Integral guides will eventually wear, but you just ream them and buy a new set of valves with oversize stems. To further guarantee healthful valve temperatures, this time at the seats, all Ford-built engines incorporate valve rotators. These little gimmicks cause the valve to settle in a different position after each cycle. They’re still turning slightly when they seat, which keeps the mating surfaces wiped clean. Tests by valve manufacturers (Thompson, Eaton, and others) show that rotators vastly prolong intake and exhaust valve life in any engine, and incidentally, several equally good designs are now commercially available for most engines.
The cooling system features a single pump with forward-curved impeller blades which force the coolant into an equalizing chamber. From there, a balanced flow is fed to both cylinder banks. It cools the bores on its way to the back of the block, then rises and returns through the heads to the radiator. The new head castings were built to insure effective cooling around combustion chambers, valve seats, integral guides, and spark plugs.

The stock intake manifold will probably be the first item thrown out when you get your new Ford, but there’s a lot to be said for it the way it stands now. It’s about as close to being symmetrical as you can get on a V8. Equal length passages to each cylinder discourage directional favoritism for any one port. Compared to some contemporary V8’s, this manifold looks a little less like a basket of worms. Equitable distribution to all cylinders is one of the key reasons why stock (7.2 to 1 compression ratio) ’54 Fords will happily digest regular gasoline.
Another asset is combustion chamber design which follows the route pioneered by Ricardo. The kidney-shaped volume has a large “squish” area at the end farthest from the spark plug. The piston coming up on compression traps some of the mixture in this confined space and literally squirts it out into the main volume, creating the turbulence necessary for even burning. Smoothly contoured intake passages and short exhaust ports add to the already high volumetric efficiency.

The combustion chamber design gives you another dividend in smooth, knock-free performance. When the charge is fired and the flame front moves away from the plug, it compresses the gases ahead. This situation in other combustion chambers is ideal for detonation, but in Ford’s, the squish area now becomes a quench area. The unburned gases that weren’t squished out are confined and cooled by contact with the cylinder head and piston. Proponents of the hemispherical combustion chamber argue that this works too effectively; that the remaining gases aren’t burned at all. At any rate, Henry’s engineers had their choice for they’ve manufactured nearly twenty-seven thousand 525-horsepower V8 tank engines with hemispherical combustion chambers. They chose the squish type for passenger cars.
So far, all we’ve said applies equally to Ford and Mercury. The two engines are basically the same. The Merc is a bored (no pun intended) Ford block with better breathing and gas-eating equipment. Where the stock Ford mounts a two-barrel Holley carburetor practically identical to last year’s, Mercury has a radical new four-barrel carburetor which is the main reason for the 30 more horsepower. You’ve guessed what we’re getting at. There’s no reason why you can’t make a Merc out of your new Ford and then start from there. Here’s how.

The Mercury intake manifold will fit on your Ford. Some filing of the manifold or head ports may be necessary to make the Merc manifold fit and align with the ports of the Ford heads. This is because the manifolds are manufactured in two different plants. Until such time as superior speed equipment is available, this will give you the advantage of four-barrel carburetion. The new carburetor depends on air flow through the primary venturis to operate the secondary venturis, eliminating the usual mechanical linkage. In other words, whenever engine requirements exceed breathing capacity of the primary venturis, vacuum acting through a diaphragm opens the secondary throttle plates to the exact position for the right amount of additional air and fuel. They’re fully open when you hit 60 mph at full throttle. The system is entirely divorced from the accelerator linkage. The primary reason behind this development is to get a four-barrel to work with a standard shift transmission. An added bonus on all Ford carburetors is an external vent for hot starts.

Exhaust valves are the same and intakes are up to you. If you want drag potential, stick with the smaller stock Ford parts. These tend to choke down the big Merc breathing system, but will give you more low speed torque. If you’re after good times through the traps, change over to the larger Merc intakes. With these, there’s little loss in volumetric efficiency at high speeds. Installation should be comparatively simple, as seat inserts have been eliminated this year. Incidentally, that’s an indication of the unusually low head temperatures in these engines.
It’s too early to tell about cam grinds as the engines haven’t been available to many speed shops for study. Ford and Merc both use the same cams and hard tappets. All we can say is to watch your clearances if you go to one of the higher lift grinds, for they’re close. But the stock 7.2 to 1 heads can stand a lot of shaving. Mercury’s version ups compression ratio to 7.5 , and remember that these engines were designed for fuels ten years in the future. A safe rule to follow is that horsepower will increase percentage-wise in approximately the same proportion as the percentage increase in compression ration, if the calculation is based on air-cycle efficiency. Figures on this basis apply to all the new, better breathing, overhead valve V8’s and holds good for ratios between six and a little over ten to one. Using this formula on a Mercury, milling to 9 to 1 should give about 176 brake horsepower. No one is too sure (except Ford engineers and they aren’t saying) what this will do to octane requirement. Our guess is about 95 Research Numbers. This is somewhat higher than is available in present premium gasolines, but you can get away with it if you drag hard enough and often enough to keep deposits blown out of the combustion chambers.

The advantages of stroking these engines are dubious. First, any lengthening of the present 3.1-inch stroke violates the basic design concept. A short-stroke engine is a low-friction engine with resultant longer life and greater fuel economy. The new Mercury will go 29 per cent farther than the ’53 model on the same amount of piston travel assuming equivalent gearing. The second objection is that stroking for low-speed torque is a waste of effort when you have good breathing and spark advance. Sure, you could gain by stroking your L-head Ford, but that engine in stock form had asthma and the vacuum spark advance ignored the basic requirements of low-speed, full-throttle acceleration.

Boring the new engines out is another matter. We have reason to believe (based on available oversize service pistons) that the ’54 Ford block can stand another 1/8 of an inch before your run out of material or get into too much oil-control trouble. For the Merc, subtract the fact that it’s already 0.125 inch oversize. Again, there’s a simple formula to check the gain. The ratio of the two piston diameters squared is roughly equal to the ration of the stock torque and the unknown new torque. With maximum stock Ford torque at 214 pounds/feet, a one-eighth over-bore puts us up to about 223. If you use the larger Mercury intake valves, your maximum horsepower will go up in the same proportion, but only if you do.

Lastly, you can order either your Ford or Mercury equipped at the agency with dual exhausts. These do not included headers in the usual sense, but even so, they’re claimed to give a three to five per cent increase in stock horsepower. Most dual-pipe manufacturers claim about the same gain. A good set of well designed headers should add even more.

Any or all of the modifications we have discussed add up to an inexpensive and fat performance bonus, especially if you start out with the Ford. We’ve drive both of these cars in stock form (MOTOR TREND, Jan. and Feb. ’54). The new Ford V8 with a standard gearbox will do 0 to 60 in about 16 seconds. An equivalent Merc (weighing very little more) is considerably faster, taking between 14 and 15 seconds. Rough calculations show that the new Ford should do 96 mph. Mercury, unless our slide rule is wrong, will do 103 – over the century mark in stock form for the first time in its history. It shouldn’t be hard for you to improve on these figures. Good luck!"

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