This article was written by Classic Inlines for Legendary Ford Magazine,
and was published in the July/August 2008 issue.
Hopping Up The Falcon Six
Earlier in this issue we briefly covered the History of the Ford Inline Six
. While the article covered all Ford inline sixes, emphasis was placed on the ‘Falcon Six’ (commonly referred to as the ‘Small Six’) due to its wide spread use and popularity. While this engine is still known for it’s reliability, excellent mileage (25-30mpg), and ease of maintenance, it's also well known for its meager and lack luster performance. The reason for this is quite simple, six-cylinder engines were generally found in the lower-priced models, who’s basic image was one of economy, rather than performance. Yet for years there have been scores of six-cylinder enthusiast searching for ways to increase the power output, while maintaining the economy and reliability (which is especially true today with the rising gas prices). Until recently, this has been a difficult task to accomplish. However the introduction of new ideas and products over the past few years has not only made it possible, it is largely responsible for the Falcon Six making a strong comeback and becoming more popular than ever.
While power is certainly an important factor, there are several other points to consider before making the decision to build a performance six. One of the first and most important considerations is cost. If your merely looking for cheap horsepower, and not concerned with mileage, handling, or appearance, then a performance six is probably not your best choice. While the cost of building a motor can vary considerably, building a mild or high performance six will generally cost twice that of a V8, based on horsepower per dollar. However if you are dropping a V8 into a six-cylinder vehicle, you’ll have the added expense of swapping the front and rear suspension (to handle the additional weight of a V8), which offsets some of the cost of building a six. In either case, you’ll need to add the expense of upgrading the drive-train, braking, and steering, which is required to safely handle the additional performance.
If you prefer a power-plant that offers 25-30 mpg, improved handling (due to the reduced nose weight), or one that draws a crowd at car shows, an inline six may be just what your looking for. In a recent poll, FordSix.com forum members were asked why they kept, and/or built their inline sixes. While the replies varied considerably, the overwhelming majority responded by saying they wanted something other than the normal cookie cutter V8. With the Ford V8’s being so popular over the past four decades, performance parts have been easy to come by and reasonably priced. However the cupboard has been, for the most part, empty and bare for inline enthusiast. And the parts that were available were generally higher priced. New products are expensive to develop and produce, and when demand is low it becomes difficult to recoup those expenses, hence the higher prices. Even with the demand being questionable, there are companies developing new products for the inline sixes. These products are making it possible to produce more power from the small six than ever before, sometimes equal to or more than that of a streetable V8. In the following pages, we will introduce you to the newest products, as well as the latest ideas and trends for “Hopping up the Falcon Six”.
To increase power you need to address the induction and exhaust systems, combustion ratio and cam profile, and the ignition system. A really powerful engine may need upgrades to the cooling system as well. Unlike many small 4-cylinder engines, you don't need to buzz a small six to 7500 rpm to make power. In fact you can build substantial levels of power and torque, at useable levels of rpm (2500-5000) for a daily driver or weekend cruiser. Installing headers and bolting on more carburetion to an otherwise stock engine, is a good place to start and will certainly help the performance. However the total gains may be disappointing and only make the shortcomings of the cylinder head, with its integral intake manifold, and the stock cam more evident. Basically an engine is a big air pump, and as such, the modifications must be performed systematically in order for them to work together and produce the performance levels you desire.
The small six was blessed with a bulletproof 7-main bottom end with ample strength to support much higher levels of power. On the other hand, its biggest shortcoming is its ability to breathe due to the design of the cylinder head, which incorporates an integral log style manifold. Although this certainly saved Ford a lot of money in manufacturing costs, it cursed these engines in terms of performance. The stock six suffers from fuel/air distribution issues that are rooted in the integral intake-manifold and cylinder head design. As such, the fuel doesn't atomize consistently, which results in poor idle quality, stumbling off idle, and an engine that is difficult to tune.
To increase the power output of the small six, one must first relieve the asthmatic conditions of the integral log cylinder head. This has been done in a variety of ways over the years, which includes everything from modifying the log or adding multiple carb pads, to completely removing it and fabricating a homemade intake. Other methods include adding a triple 1V manifold on top of the log, or using adaptors to convert to a two-barrel. While they all add power to some degree, none of these methods has been very successful for one reason or another. Modifying the log head or fabricating a custom intake manifold is beyond the experience level of most shade tree or Do-It-Yourself (DIY) mechanics, and even some professional shops. Adding a triple 1V intake, while being a showstopper, is a nightmare for those looking for reliability and maintenance free driving.
The most popular method, and the easiest, is adding a two-barrel carb by means of an adaptor which funnels the air/fuel mixture through the existing manifold inlet. While it may add some power, it is doubtful the gains are what one might expect, and it may lead to surging, hesitations and flat spots at lower rpm’s. Another popular method, which we prefer, is to mill the top of the log intake and mount a 2V adaptor directly to the log. Once the adaptor is mounted, the manifold is drilled, or hogged out so that both barrels dump into the log rather than attempting to funnel the additional flow through a hole half the size. To our knowledge neither method which utilizes an adaptor, have been tested on a dyno, hence the questionable gains. Legendary Fords has been informed that Classic Inlines and Pony Carbs plan to test both methods in the very near future, therefore we’ll be sure to follow up and keep you posted on the results.
As we mentioned in the “History of the Inline Six” Ford Australia had a better idea and recast the cylinder head with a removable alloy intake. In our next issue, we will cover the advantages of the OZ250-2V cylinder head, as well as turbochargers, superchargers, and fuel injection. The article will cover the various head swap options and the results of the latest dyno testing, which include a dyno run on a naturally aspirated 200ci, that produced 211hp and 227lbs of torque at the rear wheels. We’ll also review the two newest products to be added to the induction arena, Pony Carbs new annular discharge one-barrel carburetor, and Classic Inlines aluminum cylinder head and removable alloy intake.
Beyond induction upgrades and modifications, there are several other areas that need attention if you want to produce more power. These include the rod bolts and pistons, camshaft and valve train, exhaust headers, and the ignition system. When rebuilding the short block we always recommend balancing the reciprocating assembly. We also suggest the use of ARP rod bolts; as the stock bolts are the weakest link in an otherwise bulletproof bottom end. For most engine rebuilds we recommend using ARP studs for the cylinder head and main caps as well. When you use bolts to secure the cylinder head, or caps, the bolt is actually being "twisted " while it is being torque'd. However when applying torque to a nut, the stud is stretched rather than twisted, which increases the clamping force and accuracy, and applies a more consistent torque loading. Using studs makes it easier to assemble the engine, insuring proper alignment of the cylinder head and head gasket, and aids in the prevention of head gasket failures which is important if you plan to add boost to your inline six.
One of the most common mistakes when building a performance motor is over-camming the engine. A car that idles rough, stalls in gear, is a bear to drive in traffic and gets poor gas mileage, is still cool if it rocks when you floor the gas pedal. An engine that suffers these driveability headaches and gets blown away by a Ricer is the worst possible experience. The most prevalent reason for engines that don't run as they should, is an improper cam profile for the engine and vehicle combination. Everything about the engine build, drive-train components, and intended function must be decided upon before choosing the cam. To select exactly the right camshaft one must consider: the engine's compression ratio, the power range of the head, the intake-manifold-carb combination, the exhaust system, the transmission type (and/or torque converter stall speed), the rear gear ratio and rear tire size, and the car's weight. Once you've decided how you want the car to behave, you must build the entire engine and drive-train to suit your needs.
There are many numbers and terms used when describing a camshaft's design that must be understood when choosing a cam. It's good to know exactly how each of these specs affects the engine's performance. One of the most important numbers, is the cams duration. Duration is how long the cam holds the valves open. It's expressed in degrees of crankshaft rotation (remember, the cam rotates at half the speed of the crank). A 280- degree-duration cam holds the valves open longer than a 260-degree-duration cam. Holding the valves open longer allows more air and fuel into the engine and allows more to get out through the exhaust. Longer durations (higher number) improve top-end power but almost always sacrifice low-end torque. Lower durations improve low-end torque and make the car idle better, but limit top-end power. And you can get only so much valve lift with a short duration cam due to the rate-of-lift limitations of the lifter.
The most confusing thing about duration, is the difference between "advertised" and "at .050-lift" duration. At .050-lift duration is measured from the point where the cam moves the lifter up .050 inch until .050 inch before the lifter is all the way back down. Most cam manufacturers differ in where they start and finish measuring for advertised duration. Some start at .004-inch lift, some at .008-inch and some measure it somewhere in between. A 280 cam (advertised duration) from one manufacturer could actually have less duration at .050 than a 278 cam from another manufacturer, due to the different points at which companies measure advertised duration. That's why the .050-lift numbers are the best to go by.
The most popular cams for the Falcon six are Comp Cams H260, and Classic Inlines H264 and H274 cams. All three are excellent street cams and provide increase torque and horsepower over stock cam profiles. In general, a 112* lobe center is used for vehicles with automatic transmissions, while 108-110* lobe centers are used for those with manual transmissions. Since the lobe center controls where the power curve is applied, changing the lobe center from 112* to 110*, lowers the point where the cam starts working. However, a cam with a 110* lobe center will idle rougher than one with a 112* lobe center. A 110* lobe center will also have less vacuum, which may be important if you have vacuum assisted brakes and/or steering.
For motors with increased carburetion, a dual pattern camshaft is often preferred, such as Classic Inlines 264/274 cam. A dual-pattern cam is one that has different duration and/or lift specs for the intake and exhaust. Classic Inlines also offers a 278* solid lifter cam, which is generally good for 15-30hp over a hydraulic cam, but keep in mind that a solid lifter cam requires more regular valve adjustments. Other cam manufacturers for the small six include: Clay Smith, Crane, Clifford Performance, Isky, and Schneider.
Listed below is a general group classification for aftermarket cam profiles. The durations shown are based on .050 cam lift with a 112° lobe center. The descriptions within each group show the general characteristics of the cams in that group, as well as any recommended modifications to the car or engine. Most small six cams will be in the Class I and Class II groups.
- Class I (200° - 215°)
Good idle quality with low rpm torque and mid range performance. Works well with a stock or slightly modified engine with manual or automatic transmissions.
- Class II (215° - 230°)
Fair idle quality with good low to mid range torque and horsepower. Works well with stock or modified engines with manual or automatic transmission with a mild stall converter. Lower vacuum than stock.
- Class III (230° - 245°)
Rough idle quality with good mid to high rpm torque and horsepower. Requires improved induction, exhaust, and ignition system, plus manual transmission or automatics with a high stall converter. Good combination for Street and Strip, but has low vacuum.
NOTE: Always degree the cam when building a performance motor, never rely on the dots. Use an adjustable double roller timing chain whenever possible, and a quality rebuilt harmonic balancer. Use a high performance balancer for street/strip motors, where high rpm’s are frequent.
Everyone knows that high performance engines typically have higher compression ratios. Why, because higher compression ratios make more hp. Higher C/R's also improve fuel efficiency and throttle response. However there are also drawbacks to higher C/R’s. Simply put, once the C/R exceeds a certain point, detonation occurs. Detonation kills power and it kills the engine, literally. This is especially true with a small six, given the design of the cylinder head chamber. With that in mind, you are probably wondering how high should your C/R be? Before you can make that decision, or select your cam profile, you’ll need to know the difference between Static Compression and Dynamic Compression. It is very important to understand these differences, and how they affect your motor and your cam selection. If you do an internet search, you’ll find several good articles online. Take time to read them, and get a good understanding of Dynamic Compression Ratios before you start building your motor or purchasing parts. Classic Inlines has a good tech article on their website at “http://fordsix.com/CompressionRatio.asp”.
Once you have a good understanding of Dynamic and Static C/R, you can determine the C/R and make your cam selection. We won't go into all the calculations required, as there are numerous programs available for handling that chore. We recommend purchasing one of these programs (called Cam Utility Programs) if you are going to select the camshaft profile and C/R without the assistance of a trained professional. If your not sure, all cam manufactures will be more than happy to assist you in selecting the cam profile. However, with the available programs it is actually quite simple.
It is known that most gas engines make the best power with a Dynamic C/R between 7.5 and 8.5 on 91 or better octane. Unless you have actually measured the engine (CC'd the chambers and pistons in the bores), calculations are estimations at best and need to be treated as such. Since the published volumes for heads and pistons vary, it is best to error on the low side. When contemplating an engine with an 8.4 DCR or higher, measurements are essential, or you may wind up building another motor. Generally speaking, a small six should not exceed a SCR of 9.5:1 or a DCR of 8.4 without the use of water injection, performance coatings, or high-octane fuels, which assist in reducing the likelihood of detonation.
The two of the most common methods of raising the C/R are milling the cylinder head, and decking the block. Milling the cylinder head surface reduces the combustion chamber size, while milling the block (called decking) reduces the cylinder volume. Both methods increase the compression ratio, and both methods may be use simultaneously to achieve the desire C/R. On the 200ci block, a common practice is to zero deck the block, thus making it flush with the top of the piston. It’s also quite common to deck a 250ci block, as the stock deck heights were quite high. It should be noted that an increase in compression generates more heat, therefore one need to be sure the cooling system is in good working order. Another rule of thumb is to select a spark plug with a heat range one step cooler, and to reduce the initial ignition advance slightly.
NOTE: Milling the cylinder head .060 raises the C/R by one point.
(example: from 8.1 to 9.1)
Another way to increase compression is to use flat top pistons, or a piston with a higher compression height. While the 144ci and 170ci engines (3.50 bore) came with flat top pistons, all 200ci and 250ci engines (3.68 bore) came with dished pistons. The dish size varied from 7cc for pre ’72 engines, to 13cc in ’72-‘83 engines. However, you can also use flat top pistons from a 141ci four-cylinder Tempo HSC, as they have the same bore and compression height as the 200/250ci engines. For the 250ci you can use 255ci V8 pistons as well, which have a compression height of 1.585” verses 1.500” for stock pistons. This will raise the piston .085” higher in the cylinder, which would be the same as decking the block the same amount.
When selecting piston rings, we recommend moly rings over cast iron. Cast iron rings are fine for typical light duty service where the vehicle is not subjected to long periods of high speed and is run primarily on paved streets, or when the motor is not subjected to unusual dirt or heat conditions. However moly (molybdenum) rings are preferred for occasional or continuous high speed and/or load conditions, where the engine is subject to periods of high temperature ranges. Moly rings have a high scuff resistance, superior strength, and improved oil control and retention, which makes them better suited to performance engines where they are expected to serve adequately, through-out the entire life of the engine.
All small sixes came from the factory with steel shim head gaskets, which are no longer in production. Occasionally you can find New Old Stock (NOS) gaskets, which are .027” thick, however these are rare and quite difficult to find. Therefore the only choice is to use aftermarket composite gaskets. Victor gaskets have a compressed thickness of .045, while Felpro and Corteco gaskets have a compressed thickness of .050, therefore it is important to calculate the C/R based on the thickness of the gasket selected.
You have several options for upgrading your valve train components, including adjustable rockers, roller tipped rockers, or full roller rocker assemblies. One proven way to increase power is by decreasing the amount of valvetrain friction. Two of the biggest friction hot spots in any valvetrain are those where the rocker fulcrum rides on the shaft or stud, and where the tip of the rocker comes in contact with the valve stem. By placing a roller on the tip of the rocker where it comes in contact with the valve stem, the rocker is able to roll across the valve as it travels through its cycle, instead of sliding back and forth across the valve stem. Beside the obvious friction created here by non-roller tips, serious side loads are placed on the valve stem as the tip drags across the top of it while the valve travels up and down in the valve guide, resulting in excessive guide wear.
Another time-honored way to increase power with rocker arms is to change the ratio of the rocker. Therefore opening the valve a little further and faster, allowing more air in and out of the engine, thus creating more power. Changing from a rocker ratio of 1.5 to 1.6 generally adds about 3 degrees of valve duration. The net result is you are effectively changing your cam specs without changing your cam.
Valve springs are one of the most critical components of your engine. It is very important to match the camshaft and potential RPM range with the correct spring rate. Stock springs float around 4500rpm, and as such they are not recommended for use with performance camshafts. As a general rule we suggest up grading to a valve spring such as those used on small block applications (289/302) for mild cams, and to single springs with dampers or dual springs for high performance.
It is said that too much spring pressure is hard on valves, in truth, what’s hard on valves is the speed at which they contact the valve seat when closing. What dictates how hard the valve hits the seat? It’s supposed to be the camshaft’s closing ramp (shape of the cam lobe), but when the spring pressure is too low the valve does not follow it’s intended path and instead slams into the seat and actually bounces. Hence higher spring pressures can actually aid the valve by forcing it to more closely follow the shape of the cam lobe. However to much valve spring pressure adds un-nessacary friction, resulting in excessive valve-train wear. Therefore it is important to match the spring pressure to the profile of the camshaft.
CAUTION: When installing a new camshaft or valve springs, always check and verify the installed height, seat pressure, nose pressure, coil bind, retainer to rocker arm clearance, and retainer to valve seal clearance.
Dumping the stock cast iron exhaust manifold is usually the first thing performance seekers attend to. Headers are available from several suppliers and are offered in both single and dual out styles. Dual exhaust pipes should be 1.75”to 2.25” in diameter, while single pipes are normally 2” to 2.5” for the best results. A port divider, which is used to split the 3rd and 4th exhaust ports to enhance performance, once considered a requirement for upgrading the exhaust system, has become questionable over the past few years. Many FordSix.com forum members have installed them, only to have them break loose, which results in a very annoying rattle. Once removed the port divider is usually discarded, as very little difference (if any) is observed. It’s not clear if any testing has been done to validate the installation of the port divider, hence future testing is planned to verify the benefits, one way or the other.
Upgrading the ignition system is the easiest modification you can make, and is considered to be the best modification on an otherwise stock engine. The old points style ignition can be replaced with a Petronics unit, which retains a stock appearance, or completely discarded in favor of a new or rebuilt distributor.
Best bang for the buck, the Duraspark II distributor is hard to beat as a triggering devise for an electronic ignition system. Coupled with either a stock ignition box or an aftermarket control box such as the Dyna Module or MSD-6A, it is a tough, readily available, reliable distributor. The system consists of a magnetic reluctor and pickup in the distributor, and an ignition module to trigger the coil. They were offered as stock equipment and are a direct fit on both the 200ci and 250ci engines, providing they were built after 1964 and have the 5/16" oil pump drive shaft. Pre ’64 200ci engines, as well as all 144/170ci engines, had ¼” drives. If you want to get one from the auto parts store, make it easy on the clerk and ask for a distributor from a '78 or '79 Fairmont.
Classic Inlines also offers a performance Duraspark II distributor, which utilizes a full length bronze bushing to provide increased durability and cure top end timing fluctuations which were common in the OEM distributors. The Duraspark distributor can be wired to various ignition control modules, including a GM 4-pin module, a Ford Blue Strain module, a Dyna module with the matching Inferno coil (sold by Classic Inlines), a MSD 6A module, or similar aftermarket ignition systems.
Another option is a DUI Distributor sold by Classic Inlines. While the DUI is the most expensive system, it is also the most powerful ignition system available for the small six. Dyno testing on a 200ci engine showed an increase of 13 ponies over the DuraSpark II and MSD combo, and 20+HP over a stock ignition system.
Manufactured by Performance Distributors, the DUI dizzy is a one-piece, high performance ignition system with the coil and ignition module self-contained in the distributor cap. The one wire hook-up makes it a truly clean and simple drop in
installation that eliminates all of the messy and confusing wiring associated with other ignition systems. Unlike stock and many aftermarket systems, no ballast resistor is required, which allows full voltage for a hotter spark and superior power.
Before starting any performance upgrades, honestly assess your intended use. If you intend to use the car as a daily commuter, you probably don’t want a high duration solid lifter cam, high compression, and 5.30 rear gears with a 3600-stall converter! You certainly don't want to build an engine that is a real screamer at 7000 rpm if it's going to be used in a rock-climbing Bronco, or street driven in stop and go traffic! Keep in mind that the rest of the drive train should match the power plant for the best results. Even a properly built high-performance six may be no fun to drive if the torque converter and/or rear gears are not matched to the engine's capabilities. Be prepared to spend those hard-earned dollars, or accept the 200/250 for what it is and work within its capabilities. Either way, in the end you'll be rewarded with an economical, durable, and different alternative to V8 performance.
NOTE: For small six (144/170/200/250ci) engine owners, we highly recommend the Falcon Six Performance Handbook.
It's a great source of information.