Tuesday, July 22, 2008

Roger Huntington's Y-Block Engine Modifications

In 1962, Petersen Publishing put out a special publication by the editors of Hot Rod Magazine, titled "Ford Performance Handbook". It contained a great article on Y-Block Engine Modifications by Roger Huntington. There's much to learn from this little seen article:

There will always be thousands of car enthusiasts who are never satisfied with the standard performance you can buy at the showroom. Even when some of the factories are building out-and-out hot rods -- (which they definitely are these days) -- they're still not satisfied. They insist on the right to engineer their own "customized" performance with special speed equipment and modification procedures that have been the lifeblood of the hot rod sport for 25 years. These fellows are hopeless hop-up bugs. Sometimes they can't do any better than factory engineers. I've seen many instances where a modified Super/Stock engine didn't go any better than a well-tuned stock Super/Stock! But no matter. The hop-up enthusiast is having a ball -- and there's always the very good chance that he'll strike on just the right combination that will make a world-beater. The specialist still has every advantage over the mass-producer. The purpose of this (article) is to bring you up to date on available special performance equipment for late Ford Motor Company engines, with some hints on the application of this equipment and other special procedures to get your best performance compromise. (And engine modification is always a compromise).

I think it would be best if we considered each basic engine model separately, as they all have special problems that don't apply to the others. These basic engines (include) the '54-'57 Ford-Mercury-Thunderbird Y-V8 -- which is still used as a standard V8 in 292-cubic inch form. Here's a run-down ... '54-'57 FORD-MERC: This engine lacks the cubic inch potential of some of our later designs (maximum stock displacement was 312 inches), but it has plenty of hop-up potential within its size class.

The basic engine was available in stock displacements of 239, 256, 292 and 312 cu. in. All these blocks will take an overbore up to 1/8 except the 312, which should be limited to 3 7/8 total bore (.075" overbore). The 272 and 292 blocks will take a stroke increase of .340", but the 312 should be held to 1/4" total stroke increase (to 3.690" total). It is suggested that the beefier 312 rods be used in all stroked engines. The maximum recommended bore and stroke on the 312 block (3 7/8 x 3.69") would give 348 cubic inches. That's the potential. If you want to increase stroke the best practice is to buy a complete "stroker" kit, which includes oversize pistons (in any desired bore), rings, pins, rods, the stroked crank, bearings -- and the whole assembly is dynamically balanced to a gnat's whisker. This is the only way to go on this. Several big companies (like Crankshaft Co.) can supply. If you just want to increase the bore there are any number of California outfits that specialize in pistons for all engines. Names would include Jahns, JE, Venolia, Forgedtrue, Grant, Thompson, etc. These special pistons are available in any desired bore size, sized to any desired clearance, with crown height for any desired stroke -- and you can order them with special rraised domes to give any desired compression ratio. You can't go wrong. This is a good way to increase displacement and compression with one blow.

No other precautions seem necessary in the lower end. Stock copper-lead bearing shells are strong. Stock oil pressure and capacity are adequate. Bearing clearances could be increased to .002-.003" for a freer engine if you wish. Rebalancing the lower end, especially when you change pistons that may have a slightly different weight, is always a good idea. Piston skirt clearance should be .003-.007" for the street, but can go to .012 for competition.

Cylinder heads are another area where we can do a lot for the output of this Ford engine. Fortunately all the heads for these '54-'62 engines are interchangeable, so we can do a little switching. The '57 heads for the 312 engine had 1.93" intake valves and much larger ports than the earlier heads. The boys who are really serious generally pick up a set of these heads, then start modifying from there. Ports are cleaned out a little, matched to the manifold openings, and generally they will run a 70-degree reamer down into the valve port (piloted in the guide bore) to open the port diameter out to a seat width of about 1/16" around the outside edge of the valve. This gives a substantial increase in breathing area without reducing seat width so much that valve life is affected. It is also practical to increase the size of the exhaust valve. Some fellows machine out the seat and port to take the '57 Lincoln exhaust valve (diameter increase from 1.51 to 1.64"), then chop and regroove the Lincoln stem to accept the Ford keepers. You can get some crazy breathing out of these heads with all the tricks. One special word: Ford heads of this vintage had a considerable amount of restriction around the edges of the valves caused by the walls of the combustion chamber being too close -- so they actually shrouded the valve as it opened. Breathing can be considerably improved by getting in here with a grinder and cutting away this close restriction around the valves. Of course remember that any metal you take out of the chamber reduces the compression ratio. This can be restored by milling a little off the lower head surface. A maximum of .060-inch can be milled -- though generally .030 is enough to compensate for combustion chamber "porting". (Incidentally, milling is a cheap way to increase compression. Keep in mind that a cut of .060-inch raises compression roughly one full ratio).

Carburetion is one of your toughest problems on a modified engine. You need lots of venturi area and big manifold passages to minimum restriction at the top end (for maximum hp) -- but if you go too far you lose a lot of throttle response and torque at low speed for the street. You have to compromise if you expect to have a nice drivable street machine. Fortunately there is a terrific variety of special manifold equipment available for this '54-'57 Ford engine. The factory has cast iron manifolds to carry a single 2-throat carb, single 4-barrel, or dual 4-barrels. Edelbrock has an aluminum dual 4-barrel with conventional "180-degree" passages, three different triple 2-throat manifolds to allow for the increasing port sizes through the years, plus a 6-carb log manifold (without heat) for competition. Weiand can supply triple 2-throat and 6-carb logs -- and Offenhauser has three models of a 3x2 for the different port sizes. Edmunds has a 3x2 and dual 4-barrel in aluminum. There ought to be enough here to satisfy any need. But which carburetion layout to choose for your particular needs? Personally I like either a single 4-barrel or triple 2-throat system for the street. This seems to be a good compromise on venturi area between high and low-speed performance. Ford 4-barrels have the secondary throttles controlled by the volume of air flow through the primaries, so there is no chance of over carburetion when you suddenly open the throttle wide at low speed. Even a dual 4-barrel setup with this system isn't bad at the low end. Normally three 2-throat carbs would overcarburate at the low end. But by using one of the new "progressive" throttle linkages -- where you run on only the center carb up to about two-thirds throttle, then the end carbs open at a faster rate to full throttle -- you can get away from a lot of the response and gas mileage problems. (You still have to be careful about using full throttle at low speeds, however, as all six barrels will open wide).

The 6-carb log manifolds are great for maximum hp in competition. They're not very suitable for the street, not only because of the excessive venturi area, but they don't have provision for exhaust heat to vaporize the fuel in cold weather. If you use your car for both street and competition, and are willing to put up with a little rougher operation, they're OK. But don't expect that luxury feel.

Camshafts and valve gear can make or break any high-output engine. It's much like the problem with carburetion. A long valve open duration (in degrees of crank rotation) and high valve lift, coupled with very quick opening and closing rates, are very effective in boosting top-end horsepower. But they also knock off torque at the low end. Also the high lifts and quick rates can overload your valve springs at high rpm, cause severe valve "float" that cuts power and ruins the valve gear. No, you've got to compromise carefully on valve timing, lift and rates -- then get just the right combination in the valve gear. You have a lot of equipment to choose from in the specialty market. The big cam companies like Iskenderian, Howard's, Racer Brown, Engle, Harmon-Collins, etc., can supply complete kits that have every part engineered to match in performance characteristics, to give stable operation at the highest useable rpm. These kits generally consist of the camshaft itself, with any one of perhaps a dozen optional grinds -- plus lightweight compatible solid lifters (either flat or roller type), light tubular pushrods, adjustable rocker arms, with special high-tension valve springs and heavy-duty spring keepers and locks. The whole assembly is "tuned" to work as a unit. I can't recommend highly enough that you spend the extra money and get a complete matched kit. Hot cams used with stock lifters and springs can often wear lobes in a hurry, float valves at low rpm, clatter, fail to pull their potential. Don't cut corners. As to recommendations on specific grinds for specific situations, this is much too broad a subject to touch here. Your best bet is to outline your car specs to the cam grinder, tell him what kind of performance you want, how the car will be used -- and he will give you the optimum grind for the job. As for the problem of flat-vs.-roller lifters, there seems to be little difference in top power output. You can use stiffer springs with the rollers, to turn higher rpm, without wearing out cam lobes -- and they seem to give longer life on the street for this same reason. Some experts say the reduction of rubbing friction with roller valve lifters will add 15 to 20 hp to your net output. I don't know. I do know that roller cams are more expensive than flats ... so you always have to balance the benefits against the cost. But I still recommend a complete cam kit rather than a piecemeal conglomeration of parts when you decide to go modified in this department.

There are a lot of possibilities in special ignition equipment for late Ford engines. We have the well-known Mallory dual-point distributors, Magspark and Mini-Mag -- and there are the dual-coil distributors by Jackson, W&H and Spalding. All have installations for all Ford engines. This is all high-quality stuff that will do the ignition job under the very toughest conditions. Actually stock ignition will do the job up to at least 5000 rpm, given the right spark advance curve. The special ignitions can take it from there -- and, of course, they all feature custom advance curves that are tailored to a specific engine-car combination. This is a valuable feature. The optimum advance curve for dragging on these Ford engines seems to be an initial advance of 12-15 degrees (crank). with full advance of 36-40 degrees at a crank speed of 2000 rpm or so. Stock mechanisms can be modified to give it.

Superchargers are a very effective way to hop up any engine, since you're pumping the fuel-air mixture into the cylinder rather than depending on atmospheric pressure to force it in. As mentioned earlier ... , Ford offered the Paxton "blower" as optional equipment in 1957 (300 hp); but only a few models were put out before the AMA anti-horsepower resolution put a stop to it. But those blown '57 Fords were the hottest things in the Super/Stock class in those days. Paxton still offers that kit -- and you can still go like that with it. Add the blower to a few other hop-up goodies like cams, big bores, etc., and you've got a wild machine. Latham Manufacturing also offers a neat axial-flow blower kit for the '54-'57 Ford-Merc, driven by a flat belt from a special crank pulley. This is a larger unit, has a bit more pressure and air flow potential than the Paxton -- but it costs more. You take your choice. But either one of them will make your Ford come alive in a way you never thought possible.

No hot engine can really flex its muscles if it can't get rid of the exhaust gas efficiently. Speed experts used to say we didn't have to worry so much about exhaust restriction because the gas was being pushed out under 60-100 pounds of pressure. That's true ... but now we know that we do have to worry about the restriction even so. It'll kill an engine's performance. Notice the beautiful streamlined exhaust headers on the late Ford high-performance engines. Ford engineers have gotten the message. Unfortunately they hadn't received it in the '54-'57 period -- so you have to depend on the special "California" headers fabricated from welded steel tubing. The Hedman company can supply a full line of headers for these cars. They're a must for any all-out combination. Then take your exhaust back through dual lines. You can use either straight-through steel or glasspack mufflers or conventional baffle type. The packs have a good sound and slightly less restriction; but the dual outlet lines themselves cut back-pressure by 75% -- so you don't sacrifice much performance by using the quieter baffles. Do something about your exhaust anyway.

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