When Ford introduced the 4.6L single overhead cam (SOHC) “Modular” V-8 in 1991 in the Lincoln Town Car, it took Ford enthusiasts by surprise because it was unlike any other Ford V-8 ever made. It wasn’t like the classic FE-Series 427 SOHC V-8 that Ford had unsuccessfully conceived for NASCAR competition in the 1960s, although it was a skirted, cross-bolted Y-block design similar to the 406/427-ci FE big-block. No one knew anything about the all-new Modular V-8, except that it was an overhead cam design available only in the Lincoln Town Car for its first year. It was pretty lame at 190 hp and 260 ft-lbs of torque, especially when you consider what Ford has done with this engine (550 hp) in the years since. Racers have gotten well over 1,000 hp from these engines, and some have extracted nearly 2,000 hp.
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It took enthusiasts a long time to embrace the Modular V-8. They’re still skittish about this engine all these years later, concerned about its complexities and unknowns, and often confused by its many variations. As they began learning about this engine, there were many questions and too few answers. The Modular engine was also externally larger than the vintage Boss 429 and 427 SOHC, yet considerably smaller in displacement at 281 ci. It took a lot of getting used to, and was challenging to build power into because it was limited architecturally. It still is.
In 1992, Ford put the 4.6L SOHC V-8 in the all-new Ford Crown Victoria and Mercury Grand Marquis sedans. A year later, Ford went with the double overhead cam (DOHC) and 32 valves in the slippery 1993 Lincoln Mark VIII aero coupe, combining high-revving V-8 power with superior Lincoln luxury. The following year, Thunderbird and Cougar, which were built on the same platform as the Lincoln Mark VIII, received the 4.6L SOHC V-8 with unequaled smoothness and power. As the 4.6L engine crossed car lines, it changed the personality of the cars it powered.
Although the Modular V-8 was smoother and made its peak power at higher RPM, a common complaint was the absence of good low-end torque. You had to really spin this engine to make power. And that’s because the 4.6L engine was vastly different from the engines it replaced. Bore and stroke were modest (virtually square at 3.552-inch bore and 3.543-inch stroke) compared to the 302 and 351W small-blocks (4.000- inch bore with 3.000- and 3.500-inch strokes, respectively), which made excellent low-end torque. This has been the 4.6L engine’s greatest shortcoming for as long as it has been in production. You really have to rev this engine to make torque because its architecture doesn’t allow for extraordinary low-end torque. To make this engine more tolerable in trucks and vans, Ford had to redesign the induction system to improve low-end and mid-range torque. Trucks and vans received longer intake runners to give this engine more torque coming in.
Car Line Expansion
The year 1996 was a renaissance year for the Modular V-8 because it spread across Ford car lines quickly. The SN-95 1996 Mustang GT received the 4.6L SOHC V-8. The Cobra received quad cams, 32 valves, and a special all-aluminum version of the Lincoln Mark VIII Modular V-8. In the all-new 1997 Ford F-150 and F-250 light-duty trucks, introduced early in 1996, Ford gave the 4.6L SOHC standard V-8 power, with an optional raised-deck 5.4L SOHC V-8 built in a different engine plant.
Shortly thereafter, Ford introduced the 4.6L and 5.4L SOHC in E-Series Econoline vans and all-new Super Duty F-Series trucks, along with a behemoth 6.8L SOHC V-10 to replace the 460-ci bigblock. Although the V-10 was more advanced, it produced disappointing lowend torque, something the 460 never had a problem doing. The V-10 had a buzzysix demeanor, not the roar of a V-8 that traditional Ford big-block buffs like.
The Modular engine finally came full circle by 1999, available in virtually every Ford rear-drive vehicle, except the The Explorer and Mercury Mountaineer. These popular SUVs didn’t receive the 4.6L SOHC until 2002, a full 11 years after this engine was introduced. The Explorer and Mountaineer had to undergo complete redesigns to accommodate the massive 4.6L SOHC V-8. The Lincoln Aviator, based on the Explorer and Mountaineer, was fitted with the 4.6L DOHC, 32-valve all-aluminum V-8.
The Modular engine represented a huge investment of resources and capital by Ford. The company invested more than a billion dollars developing this engine before it entered production, ultimately using it in as many applications as possible. Despite these many applications, interchangeability is not always easy with the Modular V-8 engine family. Although interchangeability has been commonplace with Ford pushrod V-8s in the past, the Modular SOHC and DOHC engines are entirely different. Not as much is interchangeable.
And if you’re going to interchange parts, you better know what you’re doing or it becomes expensive and time consuming. The Modular engine family is very unforgiving of error; you must be very methodical during every phase of engine building.
The Modular V-8 gets its name not for its design, but the way it is manufactured. The word “Modular” reveals the quick-change nature of Ford’s Romeo, Michigan, and Windsor, Ontario, engine plants. This enables Ford to change production from one type of engine to another in a matter of hours instead of days, weeks, or months.
No matter what anyone at Ford may tell you, there are certainly political reasons for there being two basic types of Modular engines (Romeo and Windsor) much as the case with the Windsor and Cleveland small-block V-8s in the 1970s. The 351W and 351C had the same displacement, but were of very different engine architecture. Today, as in 1970, you have two different Ford engine plants doing two different things, which creates all kinds of challenges for the engine builder. As long as you’re aware of these differences, building a Modular engine becomes easier.
At the beginning of the Modular engine program, Ford intended to build a V-6 version of this overhead cam engine, which never happened. It’s easy to assume the 24-valve DuraTech V-6 is a Modular engine, but it is not. The 3.0L DOHC DuraTech V-6 is a European Ford design and not related in any way to the Modular engine. The Modular V-8 did, however, evolve into a 6.8L V-10 available in F-Series Super Duty trucks and E-Series vans, replacing 385-series 460-ci big-blocks.
When Ford engineers understood they had reached the limits of 16-valve SOHC technology, they improved breathing via a new three-valve cylinder head. That first appeared in 2004 in Ford’s redesigned F-150 atop the 5.4L SOHC engine. This head showed up on the allnew 2005 Mustang GT a year later, rated at 300 hp with 320 ft-lbs of torque. The Explorer and Mountaineer received the three-valve head for 2006 with nearly as much power (292 hp) as the Mustang GT Ford made a powerful performance statement when it teamed up with racing legend Carroll Shelby to bring back the Shelby Mustang GT500 in 2007 with extreme Modular power: a 5.4L DOHC supercharged V-8. This union created the most powerful production Mustang ever made at 500 hp.
The most legendary Modular V-8 has been in the Ford GT super car, introduced in 2003. Very similar to the Shelby’s 5.4L DOHC, the GT’s supercharged DOHC makes more power (550 hp) and has its own block designed specifically for racing. The downside to this engine is very limited block availability; and they don’t come cheap, at around $5,000 each. If you have the good fortune of owning a Ford GT, I recommend buying one of these blocks and putting it away for safekeeping. It’s a better investment than real estate, plus you may need it some day.
Although I have mentioned the 5.4L SOHC and DOHC engines in this chapter, the primary focus in this book is the 4.6L SOHC engine, which covers the basics quite well because the DOHC is essentially the same engine, except for cylinder heads and induction. The 5.4L SOHC is virtually the same engine except for deck height. Some parts are common to these engines and some are not. Very little interchanges between the 4.6L and 5.4L due to block deck height differences. Cylinder heads do interchange in virtually every application.
The aftermarket performance industry was slow to embrace this engine because, aside from the 32-valve Lincoln Mark VIII, there wasn’t a performance application until 1996. And it would be a stretch to call the Mark VIII a performance car. When Ford put the 4.6L V-8 in the Mustang GT and Cobra in 1996, racers began to take this engine seriously.There was a lot of experimentation in the early going that eventually made certain engine builders and aftermarket performance companies Modular engine experts, such as Sean Hyland Motorsport, Sullivan Performance, Modular Racing, and PowerHeads. You may find others on the Internet that have proven their product on the track. But beware: Some are nothing more than parts movers.
Ford Racing Performance Parts (FRPP) and your dealer are excellent sources for performance parts for the 4.6L and 5.4L engines because who knows better than Ford, with all its engineering resources, what works best for this engine family? However, it is also important to remember that seasoned racers and engine builders tend to know more about this engine than Ford Motor Company because they’ve managed to do incredible things with it in the real world of racing. If it can survive the extremes of racing, it can survive just about anything.
New Engine Building Process
Ford’s 4.6L Modular V-8 must be approached differently than any other Ford engine. You will hear new terms and become acquainted with fresh engine-building techniques. And be advised: The 4.6L Modular engines are unforgiving of careless engine-building technique. Get sloppy with this engine and you can plan on rebuilding it all over again. Shortcuts you might have taken on older pushrod Ford V-8 engines do not work with 4.6L Modular V-8s because these engines have unforgiving tolerances and thin-wall castings.
You must practice precision work at every phase. That same level of attention must also be exercised at the machine shop. If the shop isn’t familiar with the 4.6L engine, or doesn’t have the patience to build it properly, find a machine shop that has experience rebuilding the 4.6L because it requires specialized machining and assembly techniques. Mostly, I’m just talking patience and close attention to detail. However, don’t be intimidated. With some time and a little inclination, you can familiarize yourself with a totally new family of Ford high-performance engines and, in due course, the Modular engine will become very familiar to you.
As with any engine-building project, you must first have a plan. Because Ford’s overhead cam Modular V-8 has more variations than any Ford V-8 in history, you can’t just walk into a salvage yard and grab a pair of cylinder heads or a used block. You need to know the answers to these questions: Is your core engine a Romeo or Windsor? Are the heads Romeo or Windsor? What model year? What Ford, Mercury, or Lincoln model did it come from? Are your parts compatible at every level?
Modular V-8 castings and components are not always interchangeable. For example, untold numbers of timing covers are available for SOHC and DOHC engines. Use the wrong cover and your accessory front dress may not fit. A front-wheel-drive Lincoln Continental 4.6L DOHC block does not fit a 1996–2004 Mustang Cobra because the mounting bolt holes and bellhousing bolt patterns are completely different. By the same token, a rear-wheel-drive Cobra block doesn’t fit a front-drive Lincoln Continental.
Romeo and Windsor castings are not always interchangeable because bolt-hole sizing from the two engine plants is often different. Therefore, you either have to find compatible castings or machine your castings to work with one another. When executed properly, rebuilding the Modular V-8 can be a very satisfying experience because you are rewarded with exceptional performance and reliability.
An engine rebuild is a golden opportunity to start anew, with new components and perfectly machined surfaces married together in blissful harmony. When you build an engine yourself, you become familiar with the engine. There is no wondering what’s inside. You know exactly what you have under the hood. And, you can begin with an educated performance tuning and maintenance program that allows your new engine to live for a long time.
Contrary to the old 100,000-mile theory of engine life, engines can live 200,000 miles with regular preventive maintenance and civilized driving technique. As fragile and complex as Ford’s SOHC and DOHC engines seem, they’re actually quite rugged and able to serve you well for more than 200,000 miles if you approach them intelligently. And if you need another shot of confidence about the Modular engine, I’ve heard time and time again about 4.6L SOHC engines in fleet vehicles, such as taxicabs and police cars, that have lived 300,000 to 400,000 miles when given regular preventive maintenance. Ford designed these engines to go the distance with precision techniques and durable components.
A price comes with high performance. If you run your engine hard, meaning racing, nitrous, or supercharging, do not expect longevity. If you consistently forget to change the oil, your engine won’t live as long, either. Let it get out of tune with electronic engine control negligence, and it may not live as long. Your electronic engine control requires periodic attention, which means new oxygen sensors (there are four of them) every 75,000 to 100,000 miles.
Other vulnerable components include exhaust gas recirculation (EGR) valve, mass airflow (MAF) sensor, knock sensor(s), coil packs, ignition wires, and spark plugs. Because platinum-tip spark plugs easily function for 100,000 miles with today’s unleaded fuels, you’ve little concern there. One area neglected all too often is evaporative emissions components, which need to be replaced every 100,000 miles.
It has been said that you cannot have it all. In other words, you cannot thrash on an engine and expect it to live long. High-performance engines, when run very hard, wear out more quickly than a mildly driven stock street engine. Wide-open-throttle exerts a whole lot of heat on critical engine parts.
The hotter components become, the quicker an engine deteriorates. Every engine has its optimum operating temperature range. When you raise cylinder pressure, you exert additional forces on pistons, rings, bearings, and exhaust valves. With pressure comes heat.
When you supercharge an engine, you’re trading boost and power for engine life, and the same can be said for nitrous. When you touch a button and pin the butterflies, you sacrifice longevity for power. Power comes from tremendous heat energy that comes from adding nitrous to the air/fuel mix, meaning, of course, that excessive use of nitrous shortens engine life.
Why do engines generally live longer today than they did years ago? Better lubrication technology, lead-free gasoline, electronic engine control, overdrive transmissions, and many other factors make life easier on engines. By contrast, high operating temperatures make life hard for engines, and this is often attributed to infrequent oil changes or a cooling system that isn’t up to snuff. You must always remember engine oil isn’t just a lubricant; it’s also a coolant. Oil is in direct contact with the engine’s hottest parts (such as valvestems, pistons, rings, cylinder walls, and bearing journals) and carries away tremendous amounts of heat from these vital components. Good oil flow and a solid oil wedge where there’s pressure lubrication is everything to engine life. Good oil splash is crucial to cylinder wall and valvetrain wear.
The single, greatest benefit to engines today is unleaded gasoline, which burns cleaner than leaded fuels of the past. Engines also live longer because companies such as Exxon/Mobil, Redline, Castrol, and others have developed synthetic lubricants that offer excellent staying power, longer service life, higher temperature tolerance, and clean operation.
Mobil 1 was the first synthetic engine oil, it’s proven itself over time, and it works wonderfully well. Crack open just about any engine that has had a diet of Mobil 1 for 200,000 miles, and you find virtually no wear nor sludge. If you run Mobil 1 in your Modular V-8, change it with great regularity every 3,000 to 5,000 miles, and use a lowmicron Wix, Motorcraft, or K&N oil filter, you can easily achieve 200,000 to 300,000 miles on an engine rebuild. I offer no guarantees because every engine, and every driver, is different. However, both clean oil and civilized operation are engine life insurance policies you can bank on.
Determining Your Engine Buildup Package
To build an engine that will serve you well, you have to know what equipment it has. All the best machining techniques and highest-quality parts are worthless if you have a flawed casting or forging. This is why teardown and inspection are as critical as buildup. Close inspection of parts is everything to long engine life. And just because a part is brand new doesn’t mean it is suitable for service. I’m always stunned when engine builders install new components, such as oil pumps, without disassembly and close inspection. All new parts need to be closely inspected right out of the box.
Before beginning your engine project, you have to be committed to your plan for its use. What is the most severe treatment you intend to throw at this engine? How will you use this engine most of the time? How much money do you have to spend? The way you intend to use the engine directly affects how much you spend. Tight budgets call for a whole lot of common sense, which means knowing how to make the most of your money.
Building a 4.6L Modular V-8 costs $4,500 to $15,000, depending on your performance goals. Count on spending a minimum of $1,500 in machining costs. Expect to spend a minimum of $2,500 in “soft” parts, such as pistons, rings, bear ings, gaskets, seals, timing components, oil pump, and valvesprings. If your engine needs “hard” parts such as valves, seats, guides, camshafts, or chain guides, expect to spend more.
A mild-mannered Modular engine in a daily driver can be built for $4,500 if you do most of the rebuilding yourself. If you expect to spin it to 8,000 rpm on a road-race course, circle track, or drag strip, you can expect to spend $15,000 or more on parts and labor. Again, how much do you have in the checking account? More important, how much engine do you actually need?
Remember that power is relative. Right off the assembly line, you can buy a 500-hp Shelby Mustang capable of 160 mph. That’s the kind of power we could only dream of 40 years ago, and it was anything but streetable. You may also build a 500-hp Modular engine for your Mustang GT, Cobra, or Lightning truck and have a streetable ride you can drive to work daily. This kind of power comes at a price in terms of fuel consumption and reliability. You lose on both when you’re at 500 hp.
Building a mild street engine gives you an easy 320 hp and comparable torque, and this can be done for approximately $6,000, depending on how detailed you become. Modular crate engines from FRPP cost around $6,000 without the waiting. Much depends on how much time and money you have. With each leap in horsepower (400, 500, and up) you can expect to spend thousands more. As horsepower and torque increase, so does the price tag. But as power and price go up, reliability comes down.
We’re sometimes guilty of bench racing ego (building way more engine than we actually need). We all like to talk up our engine-building plans. But why spend more money on an engine than you have to, especially if you’re going to build it for the daily commute or weekend drag racing and cruising? Pleasure cruisers don’t need H-beam connecting rods, steel cranks, or forged pistons. And they don’t really need aftermarket cylinder heads with expensive port work, either. They need the very basics of what Ford provided in the beginning, plus improvements that make them peppy, reliable engines you can count on for years to come.
These engines don’t need much in the way of performance improvements because Ford did a good job to begin with. When the Modular V-8 was introduced in 1991, it had advanced cylinder head port and chamber technology that made it exceptional, especially when compared to overhead valve engines of the past. In 1999, Ford introduced a better, Power Improved (PI) cylinder head, which was intended primarily for the Mustang GT, but eventually found its way onto nearly all SOHC engines. This head calls for a compatible PI intake manifold.
Engine building should always begin with a mental blueprint of how your engine is going to be built: Are you going to collect castings and parts yourself, and build the engine? Are you going to begin with a manufactured short-block or longblock? Are you going to opt for an engine kit? Or are you going to piece an engine together with handpicked parts, castings, and accessories? The way you approach your engine build beforehand determines the outcome. And never has planning been more crucial than with the Modular V-8.
Should You Consider a Crate Engine?
Short- and long-block crate engines are an excellent choice that can save you money if you know and trust the builder. Regardless of who the builder is, all crate engines must be checked in great detail before you install them. In fact, I recommend that you dismantle and inspect a crate engine before installing it in a vehicle. Crate engines are still mass-produced because it could not be done economically otherwise, which means greater potential for error with the lack of close attention to detail.
If you buy a crate engine for $2,000 to $3,000, it doesn’t have the same value as an engine built from scratch at a local machine shop. Buying a lowbuck crate engine means really cheap cast pistons, rings, bearings, and the like. It can even mean .020-inch oversize pistons in some bores, with .030- inch oversize pistons in others. I’ve seen this enough times to know it is a matter of practice with budget engine builders. They cannot afford to lose the value of a single core block, especially when you’re talking Modular engines. So they fudge the rules a bit, taking some bores to different oversizes to save a block that should otherwise be scrapped or sleeved. And sleeving just doesn’t happen with budget engine builders.
This results in variations in compression ratio from bore to bore that most people probably don’t notice. But it is something you need to be mindful of during your engine-build planning. Do not waste your money on an engine built this way. All bores must be uniform in size without exception. Bearing sizes may also vary, which certainly isn’t as critical as bore size.
If you’re seriously considering a crate engine, buy the genuine article: an FRPP crate engine from Mustangs Plus. It is a popular misconception that you have to order these engines and parts directly from FRPP or your Ford dealer. Mustangs Plus offers you something Ford Racing does not: a familiar voice and great customer service from friendly people.
You should select a rebuilder who performs dynamic balancing; not all builders do. Most mass rebuilders do what is known as Detroit balancing, which is factory quick and not as accurate as custom dynamic balancing. Pinpoint dynamic balancing is critical to smooth operation.
With Detroit balancing, pistons, rods, and crankshafts are weightmatched as close as possible. This means reciprocating mass (piston, rod, rings) should be within 1 to 2 grams of the counterweighted mass. I’ve seen them as much as 2 grams apart, which is unacceptable, yet common practice. However, this really isn’t dynamic balancing; it’s a crapshoot with your time and money.
Look for painstaking dynamic balancing. This means you want pistons and connecting rods that are precision balanced to within .1 gram of one another. Some insist this is not possible. But I say it is possible to achieve this level of balance with due diligence and the investment of time. And yes, it costs more, but it’s a wise investment. Bottom line? You want piston and rod assemblies that weigh exactly the same as the crankshaft counterweights. Any irregularities in balancing can induce unhealthy vibration. You may not even feel that vibration, but your engine does. Unfelt vibration behind the wheel can create all kinds of engine failure issues.
Internal Versus External Balance
Modular engines are internally balanced, which means the crank, rods, and pistons are balanced independently of the flywheel and harmonic balancer. If you want over-the-top precision balancing, consider making your Modular V-8 externally balanced, which means that
your machine shop includes flywheel, clutch pressure plate, and harmonic balancer in the balancing process. I include the clutch pressure plate because a dynamic balance job should always include this all-important component.
Even though the manufacturer balances your pressure plate, it is not balanced with your engine. The same can be said for torque converters with automatic transmission applications. If it rotates with your flywheel or flexplate, it should be balanced with the flywheel or flexplate.
When you externally balance, you’re covering all the bases from balancer to transmission. The downside to external balancing is replacement parts. A replacement flywheel, flexplate, torque converter, or clutch has to be match balanced. Once again, it costs more, but it’s worth it for the smoothness you gain. Ask your engine builder about externally balancing the Modular engine before committing to the type of build. It is not for everyone, nor is it a good idea for every engine. On top, it’s important to understand what kind of valve work you are getting for the money. Are you getting 16 new valves with a three-angle valve job? Or are you getting valves grabbed from a huge barrel with hundreds of other used valves? Are you getting new valveguides or are you getting bronze inserts? Are they knurled guides? Or did the builder forget all about the valveguides and cheat with a fresh set of seals? These are important questions to ask the budget crate engine builder.
Crate or Kit
Budget engines from national auto parts discounters are not going to be up to the standards you might be expecting. Based on my experience with remanufactured engines, a lot depends on what you have to spend and how you intend to drive the vehicle. The occasional weekend driver or trailered show car can get away with a low-buck budget engine from one of the national discounters.
If you don’t care about having a precision build, discount-store crate engines are a nice deal for about $2,500. Outside contractors build these crate engines and sell them through discount auto parts stores. The same is true for Ford Authorized Remanufactured engines. One of these engines bought through your local Ford dealer or parts house is the same kind of engine sold through Auto Zone, Kragen, CarQuest, and Pep Boys.
Ford’s standards may be higher, but not by a wide margin. You have the same kind of warranty depending on the rebuilder and parts employed. Some warranties are in force for as long as three years. Be advised: If the warranty engine overheats or runs out of oil, the warranty is null and void. Overheat detectors prove overheating. Physical internal damage to moving parts proves the oil theory. So be smart about your crate engine and take care of maintenance issues before they become big problems.
Of all the crate engines and kits I am familiar with, I prefer the engines and kits you can order from Coast High Performance, Sullivan Performance, Sean Hyland Motorsport, PowerHeads, and Modular Mustang Racing. Engine kits, of course, enable you to see what you are getting before the mill goes together. When it is already assembled, you have no idea what’s in there. Coast High Performance gives you the best parts available in their engine kits and provides a good value for your enginebuilding dollar.
These engine kits (and all others) need close scrutiny in the area of machine work. It is very important to check new parts right out of their boxes.
All components should be thoroughly examined by a qualified machinist you trust. Cylinder bores, line bores, decks, and so on need to be checked prior to assembly. Disassemble a cylinder head one valve at a time and inspect seats and guides. This is the only foolproof method of determining what you’re getting and what condition everything’s in.
You should do this because mistakes do happen with even the best manufacturers and distributors. These days, mistakes happen with greater frequency because the marketplace has become very competitive with builders who are spread very thin. Manufacturers are under great pressure to build these engines and kits for less money. As a result, flawed parts slip through, either by accident or on purpose. So does sloppy machine work, because it is all about volume and profit. I’ve seen camshafts that don’t match the cam card (mis-packaging or poor manufacturing technique). I’ve seen remanufactured blocks with mis-sized pistons and bearings.
These mistakes can cost you plenty if they escape unnoticed. It is important for you to discover them before the engine is assembled and installed in the vehicle. The manufacturer’s warranty covers replacement of the engine, but it typically does not cover labor. Install a defective engine and you are out the installation labor costs.
How to Choose a Crate or Kit
With all of these things in mind, which engine should you choose? The choice boils down to three basic issues: budget, trust, and intended use. If you have a tight budget, the humble crate engine is a good option if you do your homework going in. With crate engines, you need to inspect some examples of what you intend to buy from a rebuilder. Talk with reputable local auto repair shops and ask them who sells the best crate engines. Repair shops do not have time to waste with customer jobs that are going to fail and have to be replaced. Professional repair shops stake their reputations on the best components available for the money. They do not succumb to off-brands and cheap alternatives. A reputable repair shop does not do it on the cheap because there isn’t time to do it over again.
The best auto repair shops go with what works and stay away from what doesn’t work. Most auto repair shops that service Fords opt for the Ford Remanufactured engines because they offer the best warranty and use the best parts. This is no guarantee a Ford Remanufactured engine is foolproof. I’ve seen a few of them with serious defects and missing parts. However, I have also seen them last 100,000 miles or more without a problem.
You might be tempted to ask me to define “good” parts. Today’s crate engine market includes offshore parts of unknown origin. Even if it is known, I’m not always sure about the quality. I typically have to inspect these parts and make a judgment call one piece at a time. This is where you need to have some faith in American auto parts suppliers and the foreign countries they deal with. Most parts from China and Taiwan are pretty good, and often of better quality than some from the United States. However, there are also offshore suppliers where metallurgical standards aren’t always high; in that case you’re accepting unknown risk.
Companies such as Federal-Mogul, Speed Pro, Sealed Power, and Fel-Pro maintain very high standards, which means you can count on great consistency time and time again. With Federal-Mogul parts, I have seen packaging from places such as South Africa, Mexico, and South America where quality is second to none. And that’s all you really need to be concerned about with your engine projects. Don’t be so concerned with where it is made; be concerned with how it is made.
Engine kits need the same kind of attention as crate engines. You need to inspect them piece by piece, measuring each part before assembly begins. This is just good common sense that will ultimately save you a lot of time and money.
Engine planning begins with knowing the path you intend to take. I’ve already discussed crate engines and kits. Now, I want to address planning and building an engine from scratch, which is for the more experienced enthusiast. However, you didn’t buy this book to take the easy way out. You’re here to learn the smartest way through an engine build.
Ideally, you find a 4.6L engine from a similar Ford vehicle that has never been apart. An intact engine has standard bores ready to grow a little. Ideally, you find a standard-bore block with less than .011 inch of bore taper that doesn’t have to be bored. Just hone the block to true and install .005-inch oversize pistons and rings. This means greater block life.
Unfortunately, it isn’t often that you find a used Modular engine that doesn’t need to be bored. Nice thing is, Modular blocks are available new, priced modestly for the budget project at around $600. Even though they are new, however, they should be checked for irregularities. All eight bores should be measured and checked for taper before being finish honed. If cylinder bore taper is greater than .011 inch, expect to bore it .020- inch oversize and precision hone it to new pistons.
So how do you tell if an engine has ever been apart? As a rule, it boils down to the condition of gaskets and hardware. The factory did a nice, clean job of gasket installation on these engines, with no sealer around the edges. Engines that have never been disturbed have virgin bolt heads without marring. Undisturbed engines have a clean, uncluttered look externally, even though they may be dirty and greasy internally.
The best way to determine an engine’s virginity is to pull a cylinder head and measure the bores. A 3.550- inch bore indicates an undisturbed engine. Typical overbore sizes are 3.570 and 3.580 inches plus .002 inch. The project engine for this book, a Mustang GT 4.6L SOHC High Output engine, has never been apart: a Romeo engine assembly ready for its first teardown.
If you want to improve power and performance, you want 1999–up PI heads. Two basic types of PI castings are available: Romeo and Windsor. Port and chamber design are identical. The use of camshaft girdles on Romeo heads make them more desirable because of their increased rigidity. However, Windsor heads are more desirable if you’re building a Windsor block. Finding a good rebuildable core takes scouting salvage yards, checking the classifieds, visiting eBay, wandering the Internet, and putting the word out for what you need. You have so many means today at your disposal for finding good, rebuildable engines, but it’s still challenging when you become very specific about what you want.
Stroke and Compression
Whenever you increase stroke, you raise the cylinder volume relative to the combustion chamber size. This means you need to concern yourself with an increase in compression. With the increased cylinder volume, you can increase the amount of air and fuel that you burn, which gives you more power.
So what is compression ratio? One popular misconception is that pistons alone determine compression ratio. This is not true. Compression ratio is determined from not only piston dome (or dish) and even the area above the top rings, but stroke, bore, and combustion chamber size. Compression is a result of piston travel from bottom dead center (BDC) to top dead center (TDC) with both valves closed. You are squeezing the entire cylinder volume (displacement) into the combustion chamber.
Compression ratio is cylinder volume with the piston at BDC versus cylinder volume with the piston at TDC. If cylinder volume with the piston at BDC is 10 times more than it is with the piston at TDC, you have a compression ratio of 10.0:1.
Five basic factors affect compression ratio:
Cylinder Swept Volume
Piston Dome Shape
Head Gasket Thickness
Combustion Chamber Size
Therefore, besides changing the stroke, you may also increase or decrease compression ratio by changing the piston dome. If you swap in pistons that are “dished” on the top, you lose compression by increasing clearance (combustion chamber) volume. This is common with stock pistons, which are often dished to reduce compression. To raise compression ratio, you can swap in “domed” pistons, which have a top face shaped like the combustion chamber that squeezes things tight. This reduces clearance volume at the top of the bore. When you reduce clearance volume, you increase compression ratio.
If you step up to an aftermarket head, keep combustion chamber size in mind. A larger chamber reduces compression. By the same token, a smaller chamber increases compression. You can adjust compression ratio with proper piston selection. A domed piston raises compression; a dished piston reduces compression. All SOHC Modular engines have a dished piston from the factory. Those with PI heads and smaller chambers have a deeper dish.
Combustion chamber volume is the actual size of the chamber in cubic centimeters. Think of the combustion chamber as ultimate clearance volume. Chamber sizes for 4.6L and 5.4L SOHC Fords are around 42 to 52 cc depending on cylinder head type.
Ford controlled compression by dishing pistons, not by varying chamber size. When chamber size changed with the redesigned PI head, Ford enlarged the piston’s dish size. Ford improved valve shrouding and quench area with the PI head, which made the chamber smaller.
Horsepower and Torque
We’ve long been told that horsepower is what “power” is all about. But horsepower is rooted more in Madison Avenue advertising than fact. In the power picture, horsepower doesn’t count for much unless you’re going racing or have your engine at high RPM most of the time. What counts is torque and when you have the most of it. Engines make torque (twist) when you feed air and fuel into combustion chambers at high velocity and squeeze the mix. Torque is the grunt that gets you going, and horsepower is the force that keeps you moving. You could say that horsepower receives all the fame and notoriety, even though torque does all the work.
Engines do their best work when they reach peak torque, where they make the most grunt. Westech Performance of Southern California, which dyno tests hundreds of engines annually, says that when an engine is below torque peak, it has more than enough time to completely fill the cylinder with air and fuel. However, when engine RPM rises above the torque peak, there is no longer enough time to completely fill the cylinders with air and fuel.
What Is Horsepower?
The power you feel from an engine’s spinning crankshaft is torque multiplied by engine speed (RPM). This idea of horsepower dates back to steam engines. James Watt invented the steam engine in the 1800s. His theory was simple. It compared the work a steam engine could do with the same work an equal number of horses could do. Watt determined a single horse could pull a 180-pound load 181 feet in one minute’s time.
This formula figured out to 32,580 ft-lbs per minute. Watt rounded it off to 33,000 ft-lbs per minute. He divided this figure by 60 seconds, which worked out to 550 ft-lbs per second. And this became the standard definition of one horsepower.
What Is Torque?
Torque is the true measure of an engine’s work. Horsepower is a measure of how quickly the engine does the work. Torque is heavily influenced by the engine’s displacement and stroke. This means the real power you derive from an engine comes in the torque curve. The broader the torque curve, the better the power package. A broader torque curve comes from making the most of the air/fuel mixture across a broader RPM range. This is best (or most easily) accomplished with a longer stroke and a larger bore. And this is what stroker kits are all about. Increasing an engine’s stroke is more about making the most torque across the broadest RPM range.
You’re never going to have the best of both worlds because engine building is always about compromise, especially on the street. However, your engine needs to be planned and built around how you’re going to use it. Your choice of camshaft, cylinder heads, and induction system determines how your engine performs and where it makes the greatest torque.
How Power Is Made
To learn how to make power, you have to understand how power is made. How much power an engine makes depends on how much air and fuel you can pump through the engine, plus what you do with that air/fuel mixture during that split-second it lives and dies in the combustion chambers.
Think of an internal combustion engine as an air pump. The more air and fuel you can huff through the cylinders, the more power you make. This is why racers use big injectors, manifolds, heads, superchargers, turbochargers, and nitrous oxide. Racers know this air pump theory and practice it with reckless abandon sometimes with catastrophic results. However, good racers also understand the “too much of a good thing” theory. Sometimes it can cost you a race. It can sometimes cost you an engine.
Getting power from the 4.6L Modular Ford requires having liberal amounts of air and fuel in the chambers, then squeezing the mixture as hard as you can without damaging the engine. When you raise compression, you increase the power your mixture yields. It is the intense heat of compression, coupled with ignition system spark, that extracts the heat energy from the mixture. The more compression you have, the greater the heat you have to ignite the mixture.
When there’s too much compression, the air/fuel mixture can ignite prematurely, causing preignition and detonation. You have to dial-in the right compression ratio to get the most from the fuel. Today’s street fuels don’t tolerate much more than 10.0:1 compression. And when you have 10.0:1 compression, forget about running 87-octane fuel. You need to run a higher octane, which becomes expensive.
This means you have to look elsewhere for answers in the power equation, such as more aggressive camshaft profiles, better heads, port work, hotter ignition systems, exhaust headers that breathe better, and state-of-the-art intake manifolds.
You don’t always have to use a higher compression ratio to achieve more power. Power also comes from how you fill the cylinder during the intake stroke and how much valve overlap you have once the fury is over. This means careful thought and selection when it’s time to choose a camshaft profile and adjustable timing sprockets.
The thing to remember about gasoline engines is this: The air/fuel mixture does not explode in the combustion chambers; it ignites in a quick fire (reaction) just like your gas furnace or water heater. Because the mixture is compressed and ignited, it lights off more rapidly. Combustion in a piston engine is a quick “fire” that sends a flame front across the top of the piston. Under ideal circumstances, the flame front travels smoothly across the piston dome, applying heat and pressure that act on the piston and rod uniformly to create rotary motion at the crankshaft.
A bad “light off” that originates at two opposing points in the chamber is referred to as pre-ignition, detonation, or spark knock. Opposing flame fronts collide, creating a shock wave that hammers the piston dome, wrist pin, and rod journal. This is the pinging or spark knock (rattling) you hear under acceleration. The goal is a smooth, quick fire, with the flame front traveling in one smooth direction for maximum power.
Power management is having the right balance of ignition timing, fuel mixture, compression ratio, valve-timing events, and even external forces, such as blower boost or nitrous delivery. All of these elements have to work together if you’re going to make productive power.
The science of making power must tie in with your intended vehicle mission. And that’s where most people often go wrong. In the quest for power, they often forget how the vehicle is going to be used. If you’re building an engine to go drag racing, the way you build your engine is going to be different than the person who builds one for trailer towing. By the same token, road racing engines should be executed differently than drag racing engines.
Street engines for the daily commute need to have good low- and mid-range torque. Drag racing engines need to make power at mid- to high-RPM ranges. Road racing engines need to be able to do it all (down low, in the middle, and at high RPM) because they’re going to live in all of these ranges while racing. Engines scheduled for trailer towing need plenty of low-end torque. They also need to live comfortably at mid-range, when they are pulling a grade.
Engines must be planned and executed for the mission or you’re bound to be disappointed. It is very hard to cross over from the world of daily driving to drag or road racing. Racing engines make very temperamental street engines because, on the street, they have to live in an RPM range where they are unhappy. We’ve all seen the radical engine in a street car that doesn’t idle or falls on its face when the traffic light turns green. This is an engine that is happiest when it is spinning at or above 6,000 rpm. This is great for the racetrack, but lousy for the street.
Tools and Equipment
When you’re building an engine, it is easy to become overwhelmed with tool and equipment choices. And it’s easy to go crazy with the credit card. That first trip to Sears or Harbor Freight Salvage is often like that first trip to a speed shop. You lay down the plastic and come home with a lot of stuff. But having lots of expensive tools isn’t always necessary for building an effective engine. You can rent and borrow tools for the jobs you are only going to do once. Other tools, such as a socket set, screwdrivers, and wrenches are useful for other automotive projects. These are the tools you purchase.
I recommend Sears Craftsman tools because they have a lifetime warranty, great reputation, and stores in nearly every area of the world. The Craftsman warranty is a no-nonsense, no-fine-print warranty. Bust a socket and Sears will replace it with no questions asked. Strip out a ratchet and Sears will hand you a new one or rebuild your old one. Sears Craftsman tools are the best tool value there is. They’re costly, but worth every penny.
The next best tool value is Husky. You can find Husky tools at nearly any home improvement or hardware store for even less than Craftsman, yet with the same no-nonsense lifetime warranty.
Basics to Buy
Here’s a list of tools that you need to get started:
Set of common and Phillips-head screwdrivers of all sizes
Set of open/box-end wrenches (SAE and metric)
3/8-inch-drive socket set (SAE and metric)
3/8-inch deep-well sockets (SAE and metric)
1/2-inch-drive socket set (SAE and metric)
1/2-inch-drive deep-well sockets (SAE and metric)
1/2-inch-drive breaker bar
Diagonal cutting pliers
C-clip pliers • Vise-Grips (Vise-Grip brand only!)
Set of punches
Small and large hammers
Five-pound sledge hammer
Torque wrench (optional, but a great investment)
Torque-to-yield gauge (mandatory with the Modular engine)
Dial indicator kit for Modular engines (available from Ford)
Crankshaft holder (available from Ford)
Drill and bits (spend the money and opt for high-quality bits)
Putty knife or gasket scraper
Hack saw (use 24 teeth per inch for best results with metal)
Magnetic bolt tray
Large chest or heavy-duty tool box with drawers
The items on this list will last you the rest of your life if you exercise good care. Tools are items you can pass along because, with proper care, they will even last several lifetimes. Most people buy socket sets, but forget deep-well versions, which you will need over the course of an engine build.
Also, opt for 6-point sockets as well as 12-points. A 6-point socket doesn’t strip a bolt head and provides a firm grip, although a 12-point is easier to fit when you’re working in a tight location.
Make sure your socket sets have at least two extensions (one 3-inch and one 7-inch). Spring for the universal adapter as well for easy access. Buy a 6-point set first; if you can afford it, buy a matching set of 12-point shallow- and deep-well sockets because they are needed with some engine applications.
Before you buy screwdrivers, hold one in your hand first. You want a screwdriver that feels good in your hand and offers adequate grip comfort and mechanical advantage. If your hand slips on the handle, it is a poor design. The tip should be super-tough steel that does not strip out or break. Invest wisely in a screwdriver; it will last a lifetime. Another idea is to buy screwdrivers with bright orange handles for visibility and safety. This lessens the chance of leaving tools where they don’t belong.
I push the idea of quality tools because there really is a difference. Lowbuck wrench sets don’t get the job done effectively. Cheap forged or cast tools tend to strip out and leave you hanging on a Sunday afternoon when you need them most. Sears Craftsman, Husky, MAC, and Snap-on tools come with a lifetime warranty you can count on. And it’s a warranty that’s good for as long as the tool exists; for you, your child, your grandchild, great-grandchild, and more. MAC and Snap-on tools tend to be very expensive and available only at better garages everywhere, which makes Craftsman and Husky an even better value and easier to find.
Proper tool care once you’ve made the investment ensures reliability. Keep your tools clean and serviceable. Lubricate ratchets periodically with engine oil or white grease for best results. Drill bits should be sharpened periodically. Do not waste your money on cheap drill bits; buy only the very best. And when you’re using a drill, run the bit slowly and keep it wet with lubrication. Drill bits begin to squeak whenever they’re dull. Invest in a drill-bit sharpener or find a reliable shop to sharpen your drill bits. Just about anyone who sharpens lawnmower blades and chain saws can sharpen your drill bits.
And one other thing: Know when to retire tools. Tools that are not serviceable can be dangerous. A loose hammerhead, for example, could rearrange your (or someone else’s) dental work, break a window, or dent a fender. Cracked sockets, worn wrenches, busted screwdriver handles, stripped ratchets, and other forms of serious tool deterioration are reasons to invest in fresh equipment. It’s about your safety and the integrity of your work.
A good rule is to purchase tools only when you need them, but it’s a good idea to start with the ones on the list at left.
Some to Rent
These are the tools you’re probably going to use only during an engine build and won’t need again until the next engine project. Therefore, you should consider renting them when needed:
Torque-to-yield (torque-angle) gauge
Piston ring compressor
Harmonic balancer puller
Freeze plug driver
Small grinder (if you port your own heads)
Easy outs (for broken bolts in blocks and heads)
Degree wheel and pointer
Piston ring compressors are available in different forms. The most common type you can rent is an adjustable-band type. The ratcheting type makes piston installation a snap. Custom-size billet ring compressors are costly and not for the novice. Engine-building professionals who build a lot of engines invest in billet ring compressors because getting the job done quickly is important. Billet compressors, which are sized to the cylinder bores, make short work of piston and connecting rod installation.
Harmonic balancer pullers can be a rental item. You may use it again and again for not only balancers, but steering wheels and other interference-fit items. They don’t cost that much to buy, which makes them a “borderline” item. Look for the “multi-purpose” in any tool you’re thinking about renting. If you expect to use the tool again, it may well be worth the investment now.
You have two basic types of valvespring compressors: one you use in the shop, which looks like a huge Cclamp, and one you use with the head installed (more like a pry bar). For engine rebuilding, you need the C-clamp type. You can sometimes pick these up at a discount house, such as Harbor Freight Salvage, for less than it costs to rent one for several days.
Freeze plug and seal drivers are also items you could use again and again. You can also use a like-size socket as a driver on the end of an extension. This saves money but could damage the socket. Don’t be a tool abuser.
Thread chasers are a vital part of any engine build because you want clean threads. Clean threads yield an accurate torque reading when it’s time to reassemble the engine. It’s a good idea to chase every bolt hole. When a thread chaser is outside your budget, use Grade-8 bolts and other fasteners with WD-40 to chase the threads. This may sound crude, but it saves you money and still gets the job done.
Tools should be rented only at the time you intend to use them. Don’t rent every tool mentioned here at the same time because you’re not going to use them at the same time. Thread chasing, for example, should be performed when the block returns from the machine shop clean, machined, and ready for assembly. Machine shops that are on the ball will have already chased your threads. And remember: Thread chasing is time consuming. Machine shops don’t generally do this unless it’s requested.
Renting engine stands can sometimes cost you more than buying. Harbor Freight Salvage has some of the best values going at $50 to $100 for a stand, but this doesn’t mean you should cut corners. Invest in a four-legged engine stand for stability and safety. The low-buck $50 stand may not hold up under the weight. And you don’t even want to know what it’s like when an engine stand fails. It’s sudden, noisy, and destructive.
Buy or Rent?
The decision to buy or rent tools boils down to how often you will use the tool and how long you’re going to need the tool during your engine build. Anytime you need the tool longer than one to three days, you’re probably better off buying it. If you have to buy, look on the bright side: You can always loan it to friends or sell it after your engine is finished. Keeping it makes it a useful piece of community property among friends.
A good engine hoist can also be a valuable piece of community property
You can pick up a good engine hoist at Costco or Sam’s for less than $200. If three or four car guys purchase a hoist together, it becomes very affordable. These types fold up and roll out of the way when they’re not in use. Set-up time is a matter of minutes. Then, you are ready to move heavy engines. Here’s a safety tip: Keep the arm in the down position whenever the hoist isn’t in use.
It is well documented that inferior jacks and jack stands are the cause of injury and even death. Buy only the best jack stands that are made out of angle iron and welded together with solid integrity. Make sure the jack stand is able to support the weight of your vehicle. That doesn’t mean using one jack stand to support the entire vehicle; it means go for a little overkill, with the confidence of knowing it can support considerably more weight than it has to.
Absolutely never lie under a vehicle supported by a hydraulic jack or mechanical bumper jack. These jacks are not safe. They can fail, with dire consequences. Jack stands, properly positioned beneath frame rails on a level surface, Absolutely never lie under a vehicle supported by a hydraulic jack or mechanical bumper jack. These jacks are not safe. They can fail, with dire consequences. Jack stands, properly positioned beneath frame rails on a level surface,offer the best protection. Make sure your jack and jack stands are always in good, serviceable condition. Keep hydraulic jacks in the “down” position whenever they aren’t in use. This keeps dust and moisture off the ram. If you allow the ram to become rusty, the rust cuts the seals, rendering the jack useless.
Torque wrenches typically are either beam or breakaway types. I recommend breakaway types that click when the specified torque is reached. Be sure you know how to properly use a breakaway torque wrench. Three important issues apply here. First, never use a torque wrench to loosen hardware. This affects calibration. Second, never over-torque a fastener. When you torque a fastener, you are stretching the bolt stock. Apply too much torque and you stress (weaken) the fastener. Specified torque readings are there to ensure fastener integrity. Third, have your torque wrench cleaned, lubricated, and calibrated at least once a year for best results.
A torque-to-yield, or torque-angle gauge, is mandatory for the Modular engine because it’s about more than just torquing fasteners. I’m concerned with bolt stretch as well, which calls for a torque-angle gauge used in conjunction with a torque wrench.
What Is Torque-to-Yield?
As you embark on your first Modular engine build, you’re going to learn a new term: “torque-to-yield,” which means you take fastener tightening to a new level. Not only do you torque a fastener, you also determine how much bolt stretch you have. With torque-toyield, you torque the fastener to a torque specified by Ford, then tighten the fastener an additional number of degrees to achieve exacting standards. Always lubricate bolt threads first.
Never torque fasteners dry. Should a bolt bottom out, know when to back it out and use the proper fastener. Never force a bolt or nut When you are installing studs, never bottom out the stud. Run the stud down to where there is approximately 1/4 inch left. When it is time to install the nut, run the nut down flush, then torque to specification. Never bottom out the stud. Again, always lubricate threads with SAE 30-weight engine oil.
Keep a Clean, Organized Workshop
I cannot stress enough the importance of keeping a clean, organized shop. Do your engine teardown work where you can catalog everything and keep parts in their rightful places. Keep engine parts and fasteners in jars or plastic containers that are labeled with a marker. Haul the block, heads, crankshaft, and connecting rods to a machine shop immediately upon disassembly. This avoids any confusion and keeps you moving on an engine build. If you cannot afford the machine shop and parts at the time, leave the engine assembled until you can afford it. I speak from experience on this one because too much is lost both mentally and physically once the engine is disassembled. Keep disassembly, cleaning,machine work, and assembly as consistent as possible.
It’s a good idea to know what you’re going to do and when you’re going to do it during the course of an engine build. Few things are more discouraging than a disassembled engine that’s going nowhere because you didn’t have a plan.
The greatest tool you can have at your disposal is patience and the desire to learn something new. Ford’s state-ofthe-art Modular engine demands both patience and knowledge if you are to rebuild it the right way. When in doubt, check it out. Confirm before doing. Remember, it always makes more sense to slow down, take your time, and do it right the first time than having to do it over again. No matter what you may think, this time-proven advice works.
Let’s get started.
Written by George Reid and Posted with Permission of CarTechBooks
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