This article was written by Classic Inlines for Legendary Ford Magazine,
and was published in the July/August 2008 issue.

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.

• 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.

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.