Ford FE intake manifolds are unique to this engine family, and instantly recognizable when compared to any other engine’s parts. One third of the valve cover extends over the intake casting, and the pushrods run through cast or machined passages in the manifold. The FE manifolds are comparatively wide and heavy, and have numerous machined surfaces that interface with the heads, block, distributor, valvetrain, and valve covers.
With an original manufacturing and performance use history that extends over a 50-year period, virtually every intake fashion and style has been produced for the FE, albeit in far fewer variations than for the more popular engines. The builder can choose from original or aftermarket; single 4-barrel, dual-quad, three 2-barrels, six 2-barrels; tunnel rams or cross rams; single plane or dual plane; aluminum or iron. Depending on the desired cosmetics and performance any of these choices can be the right one for a given project.
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FE dual-plane intake has over/under runners and an oil filler opening. Dualplane designs such as this are ideally suited for high-performance street use because they deliver quick throttle response, superior acceleration, and provide good flow characteristics at a wide range of RPM.
Rather than trying to detail every available original part number or aftermarket option, or selecting a “winner” among the plethora of intakes available, I’ll just cover general guidelines and the most popular choices. If you are interested in historical research (the FE has a vast amount of outstanding racing history), there are other publications that better serve those needs.
Jay Brown, a well-known FE enthusiast and racer, has done exhaustive dyno testing on literally dozens of FE intake manifolds. His efforts have brought some unexpected “winners” to light, and quashed a few urban legends as well. The dyno testing does a great job of delivering comparative wideopen- throttle (WOT) performance but does not quantify part-throttle behavior. Some of the commentary found in this chapter is based at least in part on Jay’s efforts.
Intake Interchangeability
As a lead in to the manifold discussion, it is important to note that every intake does not physically fit onto every FE engine. But the vast majority of them do. The exceptions are the same ones noted in Chapter 6.
The 427 SOHC obviously uses a unique intake that does not at all resemble any other FE part. Closer to a 429/460 intake from an external appearance, the SOHC intake does not have the characteristic FE valve cover rail. Relatively few variations of intakes are or have been available for Cammers, such as single and dual 4-barrel units, either reproductions or originals from the factory, and a few single-plane iterations from small specialty suppliers such as Dove. You won’t find one in the local swap meet or yard sale.
The 427 tunnel-port intakes use a unique bolt pattern and port layout; they do not mount to any of the more common FE wedge heads. At a glance, these look like normal FE parts, until you see the huge round ports. As a rare and valuable specialty item, a tunnel-port intake is not likely to be in the hands of an unknowing seller. Dual-plane and single-plane variations were produced, but always in very limited numbers and never in a production vehicle.
The 427 high-riser intakes are the “tricky” ones. They are somewhat more common than the tunnel port, and aftermarket ones are comparatively regular finds in Ford swap meets. They look like they fit on your normal 390 or 428 with a little work, but they don’t. The valve covers, and hence the gasket surface, are in an altered position and on a different angle than so-called “normal” FE engines. The port flange is considerably taller. So if you find a highriser intake—even a really cool looking dual quad or injector one— you’re best off letting it go unless you have or are willing to acquire the matching set of heads.
Every other stock FE intake manifold physically fits on every other FE engine that was not mentioned above, although some combinations may require some machining and other work. As noted in Chapter 6, medium-riser and low-riser heads are best defined by their comparative port floor position. The same is true of intakes. The port roof and sides are reasonably close to each other in dimension and well within normal port matching range. Although mismatched floors on port openings are not commonly considered desirable, such packages do certainly run. And sometimes, they run surprisingly well. The mounting bolt patterns are all the same, as are distributor openings and coolant passages.
Recommendations First— Then the Details
There is no single “right” answer when choosing an intake manifold for your FE project. You need to select an intake manifold based on a number of factors such as cosmetics, operating RPM, vehicle weight, transmission type, and engine size. Your selection will reflect a combination of vehicle components and your performance goals. Here are a few quick recommendations on those parts that are still available new.
If you are building a streetoriented FE using the popular Edelbrock heads, you would be well served to go with the coordinating Edelbrock Performer RPM intake. Good power and a good price point.
If you are building an engine for a “restomod” or an original-looking package like a Cobra, consider the Blue Thunder dual plane. It just looks “right.” It’s also the choice for an earlier car because it has the needed oil-filler tube. This is also the best pick for shaker-hoodequipped Mustangs because the Edelbrock intake’s carb pad is in the wrong spot.
When mounted in the common fashion, the front bowl of the carb hits the distributor, and therefore the FE 2×4 carbs are mounted backward.
If your FE is running dual quads, I recommend the Blue Thunder dualplane or the Dove Tunnel Wedge single- plane. Both have a factory appearance, with the Blue Thunder being restoration-style muscle and the Dove being a bit more race-car oriented. Both look proper on a vintage ride with the finned oval air cleaner, fuel log, and linkage.
These selections are not intended to be limiting or to be perceived as the only correct choices. They are just simple, proven picks from parts that are readily available. There are lots of other aftermarket and factoryoriginal options out there.
Original Parts
Factory Ford intake manifolds are almost exclusively dual-plane designs with a wide range of variations offered over the years of production. Factory intakes were made for single 4- and dual 4-barrel configurations, as well as three 2-barrel versions. Most OE performance intakes were specifically designed for each port configuration. As development continued, Ford often made changes, both incremental and major, to the intake manifolds during production. As a result, you often see otherwise similar manifolds with noticeably different plenum shapes, sizes, carb mounting pads, etc.
The majority of factory highperformance intakes were made from aluminum, although some were cast iron, such as the 428 Cobra Jet intakes. There are a lot of used aluminum intakes available in the marketplace because they almost never wear out and are rarely damaged when other engine parts fail. These days a factory manifold’s desirability, and hence price, is more dependent on the part number and date code than on any real or perceived performance advantage.
Low Risers
By far, the most common aluminum factory manifolds found in swap meets and auctions are the various low-riser pieces. Low-riser intakes are often reasonably low in profile and provide good hood clearance. They were available in a wide array of carb configurations and designs over the years, ranging from a single 4-, dual 4-, and three 2-barrel layouts. One thing to look out for (or look for, if you need one) is the intakes specifically used in Thunderbirds. These have a flat carburetor-mounting surface as compared to the normal angled pad(s) found on other FE parts.
A factory sidewinder 427 intake is shown from the front corner. Early factory intakes have oil-filler provisions, while later ones do not. Only Blue Thunder offers an aftermarket dual-plane with the oil-filler opening already machined.
This 2×4 carburetor setup sits on a Tunnel Wedge intake, and this classic good-looking factory-style combination still runs very strong today. I’ve had them at nearly 800 hp in marginally streetable combinations.
A NASCAR-era Ford experimental intake manifold shows you the engineering approach for increasing power in the 1960s. You won’t see one of these at a local garage sale.
Medium Risers
Original aluminum mediumriser intakes are a bit less common but still readily found. Some of the aftermarket reproductions are so close to originals in appearance that it’s hard to tell the difference. Certain factory 427 medium-riser intakes have a strong following among FE enthusiasts. In particular, the single 4-barrel “sidewinder,” an intake where the carburetor was mounted visibly off-center, is very popular. The “Police Interceptor” intake is another aluminum single 4-barrel part that’s worthy of note. Both of these remain popular upgrades for enthusiasts wishing to pick up power, reduce weight, and maintain a factory appearance.
The “Tunnel Wedge” manifold is a unique item. Originally made available in the late 1960s only as an over-the-counter part from Ford dealerships, this intake essentially blended the tunnel port single plane concept with the common mediumriser FE port layout. Still available as an aftermarket reproduction from Dove, the Tunnel Wedge is a surprisingly current and solid performance piece, considering that the basic design is now over 40 years old.
Aftermarket Intakes
Most aftermarket performance manufacturers have made a multitude of intake designs for the FE engine family over the years. They include pretty much every conceivable variation on carburetor count, style, single-plane, dual-plane, tunnel ram, cross ram, high rise, low profile, 4150, 4500, and more.
Before going any further, I need to clarify the term ”high rise.” In the performance market, a manifold with a carburetor-mounting pad that is physically higher than the stock unit is often considered to be a highrise intake. But do not confuse a high-rise manifold with a high-rise FE cylinder-head definition. You can indeed purchase a so-called “highrise” intake that fits on low-riser heads, but a “high-riser” intake does not fit on those heads at all.
Performance aftermarket intakes from the 1960s emulated Ford’s offerings with dedicated high-riser, low-riser, and medium-riser designs. Most current aftermarket intakes would be best defined as having a medium-riser port design with the raised floor. All of them incorporate a large enough gasket flange to fit on and seal to the more common OEM low-riser-style heads, as well as the medium-riser variations.
Aftermarket Dual-Plane Intakes
Dual-plane intake manifolds, with the port runners split into upper and lower groups and having a divided plenum, are the most popular choice for street-oriented builds. The dual-plane design has proven to deliver quick throttle response, excellent acceleration, and good driving characteristics. Virtually every OEM carbureted intake that was ever installed onto a production vehicle was a dual-plane design; that is no accident.
Used, older aftermarket dualplane intakes are readily available at fairly low cost, usually far lower than the price of a comparable factory performance part. If you are working on a budget or are seeking a 1960s/1970s appearance for your engine, one of these parts is a viable selection. Performance potential is generally decent—certainly equal to or better than most factory offerings. The patina and cosmetics “fit” the look of many FE-powered vehicles. Although the dual-plane intakes are acceptable for a street build, these older aftermarket intakes are not the best choice for a race build. Some of these, notably the older Edelbrock F-427, have a cult following of sorts and command a price premium at the swap meets.
A Blue Thunder Weber intake is shown installed. This is only available for medium-riser heads, and is cast with a fairly small port. Many Shelby Cobra owners have used Weber intakes and carbs, and they are very attractive when installed. They are available in either a straight mounting or a 15-degree inward-angled mounting for scoop clearance on a Cobra.
Dove high-riser versus medium-riser Tunnel Wedge intakes. What’s interesting is that these Tunnel Wedge intakes provide exceptional performance while maintaining respectable street manners.
This is the rear view of the Dove high-riser and mediumriser Tunnel Wedge intakes. While similar in design, the difference in plenum size and height can be seen when the intakes are set alongside each other.
Dual-plane intakes have undergone continuous development over the past 30 years, and the FE has been a beneficiary of those efforts. The current Edelbrock Performer RPM is among the best intakes available for any street-oriented project, as well as for many race engines. The Performer RPM performed extremely well in Jay Brown’s comparative testing and has been proven to be capable of supporting more than 600 hp in my own dyno development work. For a project builder who wants an intake that is cost effective, readily available, and has power delivery potential, you cannot go wrong with a Performer RPM.
In comparison, the basic Edelbrock Performer is something of a disappointment. It can best be considered as an option for somebody who simply needs a 4-barrel aluminum manifold. The cost is modest, availability is obviously good, but the casting design, port shapes, and machining leave quite a bit to be desired. Its sister, the Performer RPM, is a better part in every possible way.
Another intake for Weber carbs; this one is unusual because of the uncommon sideways orientation.
A factory sidewinder single 4-barrel intake manifold is offset-mounted but provides good flow for a factory piece. However, the newer performance intakes using better flow data, improved manufacturing techniques, and better materials yield better performance.
A Dove tunnel-ram intake is perhaps the best intake for maximum performance on naturally aspirated engines. In fact, a tunnel ram can provide exceptional performance across a wide RPM range. But unfortunately, these intakes are nearly impossible to find.
Blue Thunder FE intakes are offered in standard Holley 4150 or 4500 Dominator flange versions. The Blue Thunder dual-plane intake provides superb flow and it’s the only aftermarket dual plane to include all of the factory oil fill and vacuum-port provisions. It is a great choice for any FE engine and has a close-to-stock appearance.
The Blue Thunder dual-plane intake provides excellent flow characteristics and has a number of highly desirable features. Although it costs more than the Edelbrock RPM, it is a great choice for a 428 Cobra Jet engine, and it provides a reasonably stock appearance for any FE engine. It looks very much like an original Ford part with no visible brand logo. It is the only current aftermarket dual plane to include all of the oil fill and vacuum port provisions found in factory Ford intakes. The manifold-mounted oilfiller tube is necessary for use on 1965 and earlier engines with the correct factory valve covers. The normal 4150 flange Blue Thunder single-4 essentially matches the Edelbrock RPM for power potential, but this also offers the option of a Holley 4500 Dominator mountingflange version that is suitable for big-cubic-inch stroker engines. I’ve run the Dominator version on engines approaching 700 hp at more than 6,500 rpm and had outstanding results. One thing to be aware of is that a spacer is required to use the universal Holley carburetors or the linkage hits the manifold.
Aftermarket Single-Plane Intakes
The number of single-plane FE intakes is much smaller. A couple of them are essentially “leftovers” from the first gas crisis of the 1970s. Both Edelbrock and Holley released smallrunner single-plane designs that were intended to be “the best of both worlds,” with good street manners and power potential. The Holley Street Dominator and the Edelbrock Streetmaster are both worth chasing down as an alternative to new parts. Although the small-runner single-plane concept has fallen from favor, it turns outthat these are both very good part that deliver on their original promise. Testing has shown them to be comparable to the best of the newer dual-plane designs as manufactured, and race experience has proven them to be very competitive when properly modified. The Offenhauser Port-o-Sonic also has a strong following among FE racers as a base for extensive modification.
There are only a very few new single-plane intakes available for the FE. The Edelbrock Victor is by far the most common; the others are a group of specialty parts from Dove.
Edelbrock Streetmaster and Holley Street Dominator are single-plane intakes that share a similar external design. Independent testing has shown performance comparable to the best of the newer dual-plane intakes, and in racing these are very competitive when correctly modified.
A 1970s vintage Edelbrock Streetmaster intake has the classic “spider” single-plane appearance. Contrary to popular opinion, these do provide very good performance on the street.
The Dove single 4-barrel is available with either 4150 or 4500 carb-mounting flange. Dove is a specialty racing parts manufacturer offering both highriser and medium-riser port versions. Built for racing, these intakes have thin-wall castings to save weight, but the thin-wall design doesn’t allow room for much modification.
The Victor is available with either the common 4150 carburetormounting flange or a 4500 Dominator flange. Other than the carb base the intakes appear to be identical. In addition, the Victor can be purchased with EFI injector bungs already cast into place and machined for those wishing to convert their FE to port-style fuel injection.
While other Edelbrock intakes are ready to install as delivered, the Victor should be considered a base for modification. It can be simply unwrapped and bolted on (assuming everything fits (this is covered later), but the ports “as cast” are very small and would result in seriously restricted performance. The real design intent for this manifold was to deliver enough casting material for the dedicated builder to be able to port and modify as needed to complement the chosen cylinder heads. The Victor is, thus, a good candidate for a dedicated race engine. Just remember to include the port work in your budget.
The Dove intakes are also available in 4150 and Dominator flange designs. Being both taller than the Victor and having a larger plenum, they would intuitively be better on a large-displacement or high-RPM combination out of the box. Unfortunately, I’ve never compared them that way because I don’t run the Victor without port work. The Dove parts were originally intended for racers and racers approach things from a different perspective, with a focus on light weight. Therefore, it has thin casting designs that don’t allow for as much modification creativity without breaking through the casting surface. For many years, the Dove parts were the only singleplane
FE intake available, and some folks have gone very, very fast with them. So they are certainly worth considering.
If you are building a high-riserheaded engine and want a single 4-barrel single-plane intake, the only choice is Dove. The Dove high-riser single 4-barrel intake has huge runners, a cavernous plenum area, and is not likely to be a good fit for a low- RPM or small-displacement application. Strange as it may seem, you would be better off with the dualquad setup, which has a smaller plenum and runner size for street use. The Dove units offer a couple different port designs: the traditional Ford port, and the “P.I.E.-”style port, which is named after perennial Super Stock record holder Ray Paquet. Ray continued the development of the high-riser Ford FE engine long after most others had moved on. Compared to the factory high riser, the P.I.E. port is somewhat squared off, has a dramatically filled floor, and is in some manner the inspiration for virtually every really high-powered FE drag engine built today.
Dual Quads
Multiple carburetors are virtually a signature feature on FE engines. That big-finned, oval, aluminum aircleaner lid has become a universal icon and can even be found on non- Ford custom cars today. A well-tuned dual 4-barrel installation matches or exceeds the performance and drivability of a single 4. And nothing looks better under the hood of a classic Mustang or Galaxie.
A Blue Thunder 427 MR 2×4 intake is a faithful reproduction of the factory piece.
With the notable exception of the Tunnel Wedge, all factory dualquad intakes for traditional FE engines are dual-plane designs. Performance differences doubtless exist between the various iterations offered up by Ford over the years, but power potential is rarely the selection criteria for these purchases anymore. The collector value of the factory-equipped cars has focused attention on correct part numbers and date codes, which is outside the focus of this book.
For the casual enthusiast, the main thing is availability and fit. Essentially you can make a low-riser or medium-riser intake fit on either head configuration. If you already own an intake or get a smoking deal, that’s important. But, if you’re out shopping, it is worth the effort to find one that fits the port without modification.
This leads us to the aftermarket. Currently available dual-quad intakes for the FE are generally based on near reproductions of factory parts, with only a couple exceptions.
Blue Thunder makes the most popular dual 4-barrel intake. The dual-plane design can best be described as being inspired by the factory medium-riser piece. The intake is cast as a medium-riser design but offers the option of a lowriser port match. A very nice part, the Blue Thunder 2×4 intake has enough casting material to allow port matching to highly modified heads without welding. It has the oil-fill tube provision in the front and the rear basket opening required for earlier cars, as well as the needed vacuum and water openings for various accessories.
The design enhancements that improve performance are not externally visible, so this is a great choice for a “resto-mod” type of vehicle in which cosmetics play a big role. The casual observer would be hard pressed to know that is was not an original intake on your car.
The Tunnel Wedge is the other popular dual 4-barrel intake; Dove offers it as a reproduction part. This intake is very close to the original in appearance, but interestingly, it was never a stock part on a Ford production vehicle. Instead, it was a dealeronly performance product that Ford offered over the counter. Since it was released near the end of the FE performance program, it was likely the most advanced multi-carb intake Ford ever made for the FE. The similarity of the Tunnel Wedge to modern performance intakes is startling, with the open-air gap below the runners. They were certainly well ahead of their time, lend themselves nicely to modification, and perform extremely well today.
Dove offers several versions of the Tunnel Wedge. The traditional medium-riser configuration is essentially a reproduction of the original Ford part, said to be made from the original tooling. Dove also supplies a high-riser head iteration with either the factory port or the “Paquet” port. I’ve used the latter design in engines reaching nearly 800 hp with minor modifications—a testament to the original design.
Edelbrock recently released a dual-quad Air Gap intake for the FE. Since the RPM single 4-barrel delivers excellent power, the dual quad should offer similar performance, but to a higher level. Unfortunately, Edelbrock chose to mount the carbs close together, limiting the intake to the AFB-style Edelbrock carbs. It’s likely that FE racers will make modifications to mount larger carbs to these, and time will tell just how good the intake really is.
The Dove high-riser Tunnel Wedge is similar to the medium-riser factory part, but it’s not the same. It’s essentially a hybrid intake of the tunnel port single-plane concept with the common medium-riser FE port intake. This is an intake that Ford never offered.
A polished Tunnel Wedge makes quite a visual statement, and this provides exceptional performance for race and street applications as well. The intake certainly makes an impression when fitted to a Fairlane, Mustang, Torino, Galaxie, Thunderbird, or a street machine.
Other Choices: 3×2, Webers and Tunnel Rams
There are options out there for the FE builder who wants something different. Some of these are fairly available. Some are swap-meet or online-auction fodder, while others verge on the exotic. The three 2-barrel combination is a common swap meet find, and these are typically mounted to factory intakes, which were installed by Ford for several years in the early 1960s on 390- and 406- equipped performance cars. They perform well on a high-performance street car and they have strong visual presence. But they are actually tougher to source than the dual-quad setup and nobody reproduces the intakes. Look out for T-Bird intakes, they are flat and won’t look right on a Galaxie.
The FE Weber intakes are still available from Blue Thunder and are visually stunning when assembled. A favorite of the Cobra community, they are offered in either a straightmounting or a 15-degree inwardangled mounting for scoop clearance. Inglese sells a package with the Blue Thunder intake and carbs ready to install.
TWM (among others) offers an EFI conversion package that delivers the Weber multi-stack appearance with the advantage of electronic fuel management. This package only includes the throttle bodies, intake, fuel rails, and linkage, so you need to source the management electronics and injectors to build a functioning system—very expensive. However, this is a viable option if you are seeking to make an instant visual impression while retaining good driving characteristics. I’ve run one of these on the dyno and it ran very well.
With the aftermarket FE 6×2 Intake, getting a smooth operating throttle linkage and routing fuel lines are a real challenge. It’s a lot of parts: six lines and six pieces of linkage.
Galaxie 3×2 intake shows the carburetor-mounting angle, while the Thunderbird intakes are flat. This is because the FE engines are mounted on a downward sloping angle when installed in most Ford passenger cars. Thunderbirds have the engine mounted low and flat to minimize the intrusion of the transmission tunnel into the interior.
Dove made tunnel rams for a very short time and they are quite rare. They perform surprisingly well, look very cool, but are hard to find.
Edelbrock and Mickey Thompson made cross-ram intakes for the FE. These featured two 4-barrel carbs, which were offset—mounted essentially side by side. Unfortunately, they are not a particularly highhorsepower package, but are visually impressive, particularly on a periodstyle muscle car. If you find a Mickey Thompson intake, make sure you get the required distributor spacer as part of the purchase, so it can be properly installed.
Intakes with a variety of small 2-barrels were also available. Six 2s look pretty darn cool on an oldschool street rod. You probably won’t be fast, but you will get to work out your fabrication skills on fuel line plumbing and linkage.
Hilborn and Algon made stackstyle injectors for the FE in the 1960s. These are not at all common today. And when you do find them they are expensive, often incomplete, and still as challenging as ever to set up. The option to convert them to EFI is there and would be impressive to see, but bring your checkbook and fabrication skills.
Here’s a very expensive and exclusive fuel-injection system. TWM fuel injection system, based on Blue Thunder’s Weber intake, provides a multi-stack carb appearance. The system includes throttle bodies, intake, fuel rails, and linkage, but you need to source the electronic management system from another supplier.
If you’re taking the forced-induction route and installing a Roots-type supercharger, the Blue Thunder FE 6-71–style blower intake is an excellent option. A spacer must be installed between the intake and the blower to provide adequate distributor clearance.
This is an alternate view of the 3×2 factory intake manifold for a Galaxie.
The FE 6×2 intake (shown from the front) is a popular choice for restoration or for an original-equipment look. It’s a cool nostalgia piece and not a race part.
With the FE oil-filler tube, the end with the groove goes up and the end with the chamfer goes into the intake.
Blue Thunder offers supercharger intakes for mounting the GMC Roots-style blowers. They required a separate spacer between the blower and the intake for distributor clearance. Not many FEs are seen with the blower through the hood, but these supercharger setups are becoming more popular because Pro Street is making a bit of a comeback. But to successfully install such a setup is another fabrication exercise for the drive components. Hampton Blowers still advertises the parts as being available and may be a good resource for those desiring that package.
Pressure Checking
I pressure check any intake where I’ve made significant modifications because past experience has shown that issues often crop up.
The pressure-testing rig is simple and easy to make. I use a block of 1/2-inch aluminum stock to make a pair of block-off plates—one for each side of the manifold. These only need to cover the water passage, and are mounted to the intake using the front two fasteners on each side, along with a gasket. The thermostat opening is blocked off with a similar fabricated plate and gasket. I plug all but one of the pipe-threaded water openings, usually using the bypass hole in the front as the place to apply the pressure. Pressure comes from a normal pump-style radiator pressure tester. A dozen pumps and some soapy water are all you need to find any leaks.
This simple rig has found flaws that could have caused a lot of trouble, including cracks through pushrod holes, where the oil-filler tube presses in, or porosities in castings that were otherwise invisible.
Bolting it On—Making it Fit
Perhaps the most challenging part of FE engine assembly involves the intake manifold. The FE intake, due to its unique design, interfaces with numerous other engine parts and can be a real challenge to properly install. If everything is correct, it is easy to install, but if components and machined surfaces do not line up with the intake, it can become a true nightmare if you’re not paying attention. Some guys just get lucky, pull the intake out of the package, bolt it right down, and it fits perfectly. I’m not one of those guys, so I’ll detail the arduous process I follow for intake installation in case you’re like me.
If you combine the number of machined surfaces, the size of the intake, and the age and unknowable history of the various parts, you have a recipe for a very challenging assembly project. I’ve seen every sort of fit problem, such as pushrods that won’t go through the holes, gasket flanges that are on multiple angles, valve-cover rails that don’t line up, distributors that won’t go in, bolts that won’t fit, broken castings, and leaks. Yes, lots of leaks.
A solid cover is used on intakes when a breather is not required.
A breather cover has an integral tube, and provides an alternate hookup to a PCV line or remote crankcase vent.
The breather separator keeps oil mist from leaving the engine.
Crankcase breather basket installs in the rear of an early-style intake. This is used in concert with a breather element or road draft tube.
Intake bolt-hole alignment is important to prevent manifold damage. Improper alignment results in intake cracking at the boss, as well as stripped threads.
A simple pressure-checking rig can be created using a radiator-pressure tester and some aluminum stock. Pressure testing ensures that you do not have any coolant leaks to contaminate the oil.
On this intake, we found a leak at a casting parting line in the water jacket when pressure testing the coolant system.
The proper distributor fit in intake is viewed from another angle. If the distributor shaft is off-center, you may not be able to turn the distributor for timing adjustment, or you may get an oil leak.
Pressure-checking plates are fabricated from 1/2-inch-thick aluminum stock and need only cover the water openings in the intake.
On some Dove intakes, this water coolant passage is exposed to the outside of the gasket opening and will cause a water leak if not addressed. If the opening goes behind the gasket you need to fill it with a bit of weld or epoxy to prevent a leak.
An overly aggressive installation of the filler tube led to a water leak that was found in the oil-filler tube opening. So, lesson be learned, don’t use too big of a hammer!
Correctly installing the distributor shaft through the intake manifold can be a little tricky. When the gap is even all the way around the shaft, the distributor is correctly centered in the manifold.
Purists do not like the idea of milling intake manifolds. Their position, and it’s a valid one, is that you are making the manifold unusable in future engine builds with other blocks or heads. Personally, I will do anything needed to make one fit because my concern is the engine that I am building now and all the components need to be compatible with one another. I am not very concerned about an undetermined build in an unknown future. Here is how we do the job:
Milling Intake Manifolds
Milling the intake should provide a reliable seal for three surfaces: gasket flange, valve cover, and front and rear ends.
1.
First check your bolts. The various FE intake manifolds have a variety of required fastener lengths. If the bolt does not have enough thread engagement or bottoms out in the cylinder head’s holes, nothing is going to work correctly.
2.
With all surfaces clean, lay a set of intake gaskets in place on the heads. I use Blue Thunder or Mr. Gasket parts for this step because they have no embossed sealing beads. Do not use any end seals at this time.
3.
Lay the intake manifold in position, being careful not to disturb the gaskets. Use the flat of your hand or a plastic mallet to move the intake around until you can slide the distributor into position. The distributor serves as the front-to-back and side-to-side locating dowel; you are not installing it “for keeps” yet, but you want to center the hole in the intake around the distributor’s seal as closely as possible.
Installing the distributor in its proper location is a key to getting proper intake fit.
4.
Next, look at the intake from the front and rear and use a stack of feeler gauges to level the end-seal surfaces from side to side. I call them the “China walls,” and typically, I see a gap of around .120 to .170 inch. There is no critical number (you need to have a decent-sized gap) but anything under .030 will probably bottom out before the intake gaskets seal up, and this requires you to repeat the process later.
Here we are measuring the gap at the front “China wall.” You want this to be at least .060 inch and level. Too tight and it can prevent the intake from sealing.
5.
The intake is now properly positioned on the engine. Next take a flashlight, a dental mirror, and inspect for port alignment and bolt-hole alignment. You should be able to see the bolt-hole threads in the heads centered in the manifold openings. The intake and head port sides and roof should all line up. This almost never happens, unless you’ve already gone through this part of the process when porting the intake or if all the parts are new and to spec.
6.
If both the bolt holes and the ports in the intake are higher than those in the heads, it is a fair bet that the intake gasket surfaces need to be milled. The FE head gasket and intake gasket surfaces are 90 degrees relative to each other, so any machining operation to the heads or block deck will have had a corresponding impact on the intake fit. Write your findings on the intake with a Sharpie-type marker—you’ll need the data later.
7.
Next take feeler gauges to the front and rear corners of the intake sealing flange of the heads. Probing between the intake gasket and the manifold, try to slip in a .010 feeler gauge in the top and bottom of each corner—front and rear, left and right. You are checking for matching angles between the intake and the head. If you cannot fit anything larger than .010-inch at any position, it’s good. Now, it’s time for the Sharpie again. On the respective corner of the intake, write the size and location of each variance. An example might be .020 inch at the top and .005 at the bottom of the left front.
We do our intake flange checking with a feeler gauge, and inspect front and rear, top and bottom. Warped and poorly machined FE intakes are extremely common, and cause a lot of post-build problems with poor running and oil consumption.
Checking the intake manifold fit at both the bottom and the top edge reveals any angle variances compared to the head. Problems here are far more common that you’d expect.
8.
Take a quick look at the valvecover rail. If the part on the intake is higher than the part on the head, use a dial caliper or a feeler gauge to find out by how much. If it’s more than the amount to be removed from the gasket face, your machinist needs to trim that surface as well. For example: if you take .020 inch from the flange and the rail is .040 too high, it’s still going to need an extra .020 inch taken off to get level to the head’s corresponding rail surface.
To check valve cover rail alignment, you need to get the gasket and rail as level as possible. The gasket can only accommodate a small amount of variance.
9.
If your first group of measurements noted that the intake had to be milled by .020 inch to line up the bolt holes, and your second group indicated that it was looser at the top by .015 inch due to an angle variance, you want to cut that gasket face at an angle—removing .015 inch at the top and .020 inch at the bottom. This fixes both problems in one cut. If you are making big angle changes, check the spot faces on the mounting fastener holes too. An angle contact breaks the mountinghole boss, necessitating a common repair seen on older intakes.
Take off the manifold and sit down with the person who’ll be doing the work. Show all your scribblings, and explain how you arrived at them. If he or she won’t stop and listen, and understand, find another machinist because you cannot put the metal back on once it has been removed. I tend to draw lots of pictures and angles, along with putting all my measurements on the manifold itself. It makes it easier to avoid misunderstandings.
10.
After machining, clean out all the chips and reassemble the intake onto the engine. The bolts should line up now, and can be lightly screwed into place. Don’t use any adhesive or sealant because you are not done yet.
11.
Pushrod fitment is the next step. Dry assemble the valvetrain with the lifters, rocker assemblies, and pushrods. Do a rough set on valve lash. Turn the engine over and watch the pushrods carefully to see if any of them hit their respective holes in the intake. Most mild combinations are okay, but engines with larger cams cam have an interference problem. The dental mirror and flashlight come in handy again because contact can be at the lower end of the hole where it’s tough to see. Sometimes it’s helpful to slip a light below the intake through the distributor or rear breather openings. If nothing hits, you can proceed with the assembly. If it does hit, mark the offending spots, remove the manifold, and grind for adequate clearance. This is a case in which it’s okay to get close, but not to touch. If you grind through into an intake port, you need to weld it up or install a sleeve into the pushrod hole. Brass tubing stock from the hobby supply shop works nicely when retained with a bit of epoxy.
Note the intake pushrod hole clearance. You want to rotate the engine through several cycles during test assembly to verify smooth operation of every pushrod at all valve-opening positions. Hard contact when the engine is running causes the pushrod to pop off the rocker arm. And you definitely want to avoid that.
This is a detail photo of pushrod tubes in intake. In order to install the pushrod tubes, a light push and the use of some epoxy are all that’s required.
Port Matching and Beyond
With the wide variety of intakes and heads available for the FE engine family, it’s almost a given that a certain degree of modification is required during assembly of the top end. I do the port alignment and matching work at the same time as the fitting process.
1.
My port-match technique is pretty straightforward and goes quickly once you’ve tried it a couple times. I port match to the heads but not the gasket. Gaskets get trimmed as needed. First, make the intake fit (as discussed above). You can’t port match the intake if it then has to be moved in order to fit.
In the first step of port matching, use a Bridgeport to rough-in the new enlarged openings. You don’t want to go beyond the edge of the guide marks, so be careful. Remember: If you remove too much material, you cannot add it back on without a welder. You just need to get close to the edge, so you can hand finish them to fit.
2.
Next paint the intake manifold and cylinder head gasket faces with machinist’s dye and let them dry. Be certain to put 1/2 inch of the dye around the front, rear, and top of the head—that’s where your transfer markings will be.
3.
Now use a straight edge and scribe to mark a line delineating the top and bottom of the ports along the head’s intake gasket surface. Use a small square to draw vertical lines along the sides of each port extending to the top of the gasket flange. Use your scribe or a Sharpie to extend these vertical and horizontal lines onto the dyed area around the top, front, and rear of the head.
The intake is properly marked so the intake and its gasket correctly align. I used a Sharpie to illustrate how to align this intake. Typically, I scribe a layout line after coating the surface with machinist’s dye.
Some intakes do not accommodate large ports without welding and a bit of rework, but this fabrication work is only seen from the inside and not noticeable once the engine is assembled.
4.
Next lay some gaskets in place and mount the intake as normal using the distributor and a couple bolts. There’s no need to tighten them at this point. Using the marks you just made on the heads, extend them onto the matching front, rear, and upper surfaces on the manifold. Remove the intake.
When porting the intake manifold to accommodate race heads, the factory and Dove intakes often have a small indent in the casting above each port that may need to be filled with weld to allow a good match.
5.
The marks can now be “wrapped” around to the intake’s gasket flange and drawn in the dye using the straight edge. At this point you’ve located all the head ports vertically and horizontally, which is all that’s necessary to measure and duplicate the corner radius. Every porter finds a preferred corner radius on a particular head and duplicates it on the other ports of the head. I use anything handy to measure and duplicate their chosen corner radius. A selection of deep-well sockets will usually work nicely, and those are always nearby. Scribe the matching radius into the dye at each port outline, and your map is complete.
The extensive plenum modifications on a Dove single-four high-riser intake was done to dramatically lower the operating RPM range of the intake for a specific competition environment.
When shaping the ports of the intake, I use a Bridgeport mill to get the first 1/4 inch of the opening shaped, but it can be done very nicely by hand with a die grinder. Use a carbide burr that is made for aluminum, it has wider spacing between the cutting teeth and won’t clog with aluminumshavings. A protective layer of masking tape around the port opening on the gasket flange comes in handy if you’re nervous. Go slowly, use a steady hand, and remember that the idea is to get a smooth transition from the intake into the head. No big bumps, no lumpy shapes, and don’t try to “bellmouth” the runner. Be really cautious around the pushrod openings. A sanding roll on the die grinder can be used to straighten, finish, and polish the port surface.
There are cases in which the port opening extends beyond the casting surface. To resolve this problem, weld before grinding the opening. Certain factory and Dove intakes have a small depression cast into the top of each runner just above the port. At Survival Motorsports, we sometimes fill that area with weld before working on the ports. Similarly, sometimes we cut through the pushrod tubes and use the welder or brass tubing as a fix.
We let our head porter do any radical modifications, but smoothing and blending the casting in the plenum and entry is worth doing. Don’t go for sharp edges; rounded corners, gradual entries, and smooth transitions. That noted, only the engine tested in the field on a dyno can tell you what works best. I’ve seen some really horrible-looking work that ran great, and some really pretty stuff that was not up to expectations.
Port alignment is important if you are going to get the most out of your cylinder heads. Here you see an edge hanging out into the airflow path—an undesirable situation.
Final Installation
You can (finally) complete the assembly once the procedure has been checked, you know everything lines up and is square, and no components are hitting one another. My preferred gaskets are either Blue Thunder or the newest steel-lined Fel- Pro parts. Blue Thunder gaskets are easier to trim for custom port shapes but Fel-Pro parts are more readily available and have integral sealing beads. Avoid the traditional Fel-Pro Printoseal race gaskets in street-oriented FE builds. The reason is that the FE’s unique intake surface is entirely surrounded by oil, and the nonreinforced race gaskets absorb the oil and fail in continuous street service.
Weld-in EFI bungs are added when converting a carb intake to injection. Only the Edelbrock Victor is available with EFI bungs already cast into the intake.
1.
I use Motorcraft TA-31 diesel application silicone as a sealer because it is highly oil resistant, dries to a near plastic like consistency, and has a gray color that looks good against an aluminum intake. Put a thin “finger wipe” layer on the front and rear end seal surfaces first, and then apply a thick bead. The thin layer assures good adhesion to the block and intake. Use a very, very thin layer that is like a coat of paint (not a bead) and this should be the same sealer on the water and port openings. With the FE’s tendency to leak, a little insuranceis a good thing.
2.
Install the intake while the silicone is still wet. Now, you want it to stick, right? Move the intake around just like the test fitting, using the distributor as a locator.
3.
Install all the fasteners loosely before tightening any of them. You may have to tap the intake around to get them all into place so you don’t need a tight one holding it. If you are installing factory-style dual quads, don’t forget to install the fuel log under the appropriate bolts.
4.
Once all components are correctly positioned, you can tighten the fasteners. The factory manual has a torquing pattern, but you can torque down the fasteners from the inside out in a spiral. They do not need to be really tight, just snug, and it’s nearly impossible to put a torque wrench on many of them, in any case. If the fit is correct you are often able see a really, really tiny bead of silicone showing around the outside of the port openings by looking down into the valve cover area.
5.
Next pull the distributor back out. Usually you need to clear a bit of excess silicone from around the opening. Let the silicone dry (overnight is best) and use a sharp Xacto or hobby knife to trim the excess from the front and rear edges. If the intake gasket protrudes above the valve cover rail, you should also trim that level.
Finally—you’re done.
Written by Barry Robotnik and Republished with Permission of CarTech Inc
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