Ford Big-Blocks: The Ultimate Cleveland 335 Series Engine Guide

While this chapter isn’t intended to cover a step-by-step rebuild of the 351-ci Cleveland, or 351C, I hope to provide some interesting insight into the history and unique features of this successful engine series. The engine featured here was undergoing a highperformance rebuild at Jordan Automotive Machine and belongs to Lee Lundberg of Mount Laurel, New Jersey.

 

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At the recommendation of Master Machinist Gil Jordan, the Cleveland received modifications that take advantage of advances in technology since the engine was first assembled, and a combination of aftermarket performance parts that resulted in a stronger, more powerful engine for Lee’s 1970 Torino GT. The Cleveland currently displaces 408 ci thanks to a .030-inch overbore and an aftermarket stroker crankshaft. It has also been converted from a hydraulic flat-tappet camshaft to a more efficient roller style, and features a high-output ignition system. Needless to say, the Cleveland now moves the big Torino down the road with very little effort.

Ford engineers designed the 335 series engines (including the 351C) to power passenger cars and light trucks in the early to mid 1970s. As is usually the case, though high-performance versions were available, certain engineering compromises had to be made in order to fit the engines into the vehicles and also to meet government emission control standards. Those who took the 351C racing soon identified the engine’s performance shortcomings and came up with innovative modifications to increase performance and reliability. While never as popular as the 350-ci Chevrolet small-block V-8, the 351C won enough races and attracted enough attention to garner the aftermarket parts support to compete on the high-banked tracks of NASCAR and drag strips across America.

 

The 4-bolt main bearing cap registers reveal that this is a Cobra Jet, H.O., or Boss 351-ci block. These three high-performance versions of the 351-ci Cleveland were the only 335 series engines to feature 4-bolt main caps.

 

One major difference between the 351-ci Cleveland (351C) and its 351-ci Windsor (351W) cousin is in the manner that engine coolant is routed. The water inlet for a 351, which is designed to first route coolant through the block, is shown here on the left. Windsor series engines route coolant through the cylinder heads first via an inlet located on the intake manifold.

 

The 335 series Ford engines are the only ones to feature a fuel pump mount on the block with a vertical bolt pattern. This is machined into the block’s integral cast timing-chain cover as seen here.

 

It would appear that this cylinder block left the Cleveland, Ohio, engine foundry with hugs and kisses cast in. Seriously, I’m not really sure of the purpose for the Xs and Os in this casting, but I would surmise that they have to do with internal controls at Ford’s Cleveland foundry.

 

The upper casting number on this 351C cylinder block reveals that it is a 351 Cobra Jet cast in 1972. The lower casting is the date the block was cast at the Cleveland Foundry.

 

The numeral “4” cast in the upper right corner of this Cleveland cylinder head indicates that it is for a 4-barrel-equipped engine. Also seen here are the date code casting and the bosses for mounting fulcrum-type rocker arms to the head.

 

Here is the cleaned-up 351C 4-barrel cylinder head set up in the machine for surfacing. This head surface is being trued to ensure optimum sealing, but it will not be cut any extra to achieve a higher compression number.

 

Performance Tip

The pedestals for the fulcrum type rocker arms are milled down in order to convert this 351C cylinder head to accept studs to mount adjustable rocker arms for high-performance use.

 

In this photo, the bronze valveguides, which have been installed in place of the worn OE guides, are reamed to fit the stem diameter of the valves to be installed.

 

This set of cylinder heads will receive stainless-steel intake and exhaust valves. The huge intake valves allow the 351C to breathe deep and make tremendous power at high RPM.

Performance Tip

 

As is the case with all Ford cylinder heads, the 351C needs to take advantage of any help it can get on the exhaust side. The pointer shows a shoulder in the casting under the exhaust valve, which will be ground smooth to promote airflow.

 

The OE-type valveguide is shown here on the left. The bronze guide shown on the right provides superior heat transfer and lubrication properties.

 

While the intake ports on the 351C are fantastic as delivered, they can also benefit from a little attention from the grinder as pointed out here.

 

This Cleveland cylinder head is being cut to receive new valve seats, which in turn will accommodate oversize valves to be installed

 

The 4V Cleveland head’s intake ports (top) are considerably larger than those of the 2V version (bottom). And while the larger port provides tons of power at high RPM, the low-end and midrange performance tends to suffer.

 

The same holds true when comparing the 4V head’s exhaust port (top) to that of the 2V version (bottom). Ford engineers sacrificed efficient flow on the exhaust ports of all 335 series engines in an effort to accommodate various engine compartment configurations. Racers corrected this flaw by raising the port, which increased flow dramatically and turned the Cleveland into a winner on the track.

 

The 4V Cleveland cylinder head (top) featured a closed combustion chamber for higher compression, as compared to the open chamber of the 2V head (bottom).

 

A comparison between the exhaust ports of the true small-block Ford cylinder head (top) as used on the 289 and the 351C 4V exhaust port show a marked difference in size and design.

 

Here, the highly touted 350-ci Chevrolet small-block cylinder head’s exhaust ports (top) are compared with those of Cleveland head, the 2V version.

 

When compared to the exhaust ports of the 351C 4V cylinder head (bottom), the 350-ci Chevrolet’s ports (top) pale even further.

 

This set of fully prepped and modified 351 4V cylinder heads sit on the bench at Jordan Automotive Machine awaiting final assembly and installation. The matched camshaft kit selected for this engine includes Crane valvesprings.

 

This outstanding-looking pair of fully assembled cylinder heads awaits completion of the 351C short-block on which they will rest.

 

The final test. The completed cylinder heads are vacuum checked to verify that the valves have sealed tight prior to installation on the block.

 

Performance Tip

Perhaps even more than other Ford engines, the 351C benefits from simple modifications to its oiling system. The main oil feed from the pump has been opened to match the gasket and pump then chamfered to smooth the oil flow.

 

Oiling System

The hot rod aftermarket industry wasted little time addressing a shortcoming in the 335 oiling system that showed as soon as racers started to really lean on them. It seemed that during high- RPM operation, not enough of the engine’s life-giving oil was feeding the crankshaft main bearings and engine failures were occurring on a regular basis.

To keep more of the oil where it belonged, Moroso Performance developed a restrictor kit. The kit required the small oil holes in the block’s number-2, -3, and -4 main bearing saddles, which feed the camshaft, to be tapped for 1/4-inch by 20 .040 restrictors. The number-5 saddle received restrictors in the holes that feed the camshaft (center hole) and the lifter gallery (right side). The number-1 main bearing oil passages where left unrestricted due to the main and camshaft oil passages crisscrossing at that point. All-out racers using roller tappets were also known to have the lifter bores in the block opened up and solid bushings installed to further limit the amount of oil traveling to the top of the engine.

 

Likewise, the oil gallery that feeds the filter has been enlarged and smoothed.

 

Performance Tip

The block’s main bearing oil passages have been matched to the holes in the bearing inserts and chamfered to ensure a smooth flow of lubricant to this most vital area.

 

The 4-bolt main cap (top) was used in the Boss 351, Cobra Jet, and H.O. versions of the engine. Below it we see the standard 2-bolt Cleveland cap. While adequate for general use, the 2-bolt cap is less desirable for high-performance use.

 

Running a tap down all the main bearing cap holes removes any left over burrs or dirt. This allows for the smooth installation of hardware and accurate torque readings during assembly.

 

Performance Tip

To further strengthen the bottom end for extreme high-performance use, this 4-bolt Cleveland block is being fitted with studs to secure the main bearing caps in place of the standard bolts.

 

Performance Tip

This particular engine is being assembled with a high performance Scat aftermarket crankshaft. The throws on this crank have been “knife edged,” a process that removes unnecessary weight and strengthens the part by removing sharp edges where cracks normally appear.

 

True to its performance nature, this Scat crankshaft has been delivered with its oil passages already chamfered and smoothed to ensure adequate oil supply to the bearing surfaces under all conditions.

 

The counterweights, or throws, of this crankshaft show evidence that a great deal of material has been removed during the balancing process.

 

The crankshaft receives a thorough cleaning that includes running a bore brush through all the oil passages prior to being installed in the block. This ensures that no foreign material has been left during machining processes or shipping.

 

The OE 351C vibration damper is showing its age, particularly in the snout area that contacts the timing case cover seal, which appears worn and galled. While repair sleeves are commercially available to remedy this situation, a dedicated highperformance engine might be better served with a new damper.

 

Performance Tip

A number of aftermarket companies, such as Performance Products, sell dampers designed for extended life at high RPM and are SFI approved for use in most racing series. High performance dampers are marked with additional timing gradients that ease engine tuning. This particular damper includes a Ford engine-specific spacer to ensure drive-belt alignment.

 

The main bearing caps are fitted with bearing inserts. Careful attention has been paid to the alignment of the oil passages in the cap shown on the right to ensure adequate lubrication.

 

The OE damper on right will be replaced by the Performance Products damper on left. The two circular marks on the outside ring of the Performance Products damper indicate where material was removed during the all-important balancing.

 

Performance Tip

The original equipment 351C connecting rod (left) is much heavier and uses a bolt and nut to secure the rod cap, while the Scat rod (right) is lighter, provides clearance for a longer crankshaft stroke, and uses cap screws to secure the rod cap.

 

The stock 351C piston and connecting rod assembly is shown on the left. For this particular engine, it will be replaced with the modern highperformance piston by Diamond and Scat connecting rod on right. Modern pistons such as this forged piece, have a much shorter skirt and are thus much lighter than stock.

 

The Diamond piston has a radically revised dome compared to the original equipment 351C piston on the left. This helps achieve the desired compression ratio and increases combustion efficiency.

 

The rings are in place and properly spaced as per the manufacturer’s recommendation prior to installing the rod and piston assembly.

 

With the rod and piston fitted to the crankshaft, the assembly is rotated 360 degrees to ensure that there is proper clearance between the connecting rod and the bottom of the cylinder bore. This step is required here due to the fact that this engine has been fitted with an aftermarket crankshaft with a longer stroke to increase its displacement. This is not a concern when using a stock stroke crank.

 

The clearance between the piston skirt and crankshaft counterweights needs to be checked (see pointer) due to the increase in stroke provided by the aftermarket crankshaft.

 

Other components may be installed only once it has been determined that there will be no interference between the parts in the rotating assembly.

 

Connecting rod side clearance is easily checked without the use of sophisticated tools. A common feeler-gauge set is used to ensure the clearance between the rods is within manufacturers specifications.

 

You can check crankshaft endplay even without a dial indicator. Using a feeler gauge on the thrust bearing cap (number-3) while prying the crankshaft forward should give an adequate reading.

 

A thin coat of RTV placed in the groove for the rear main seal is inexpensive insurance against leaks.

 

The seal should be installed slightly off center in both the block and the main cap so that butted ends are not parallel with the cap/block mating surface. This offset will help avoid leaks. Read the installation instructions carefully and make sure you have the lip of the seal facing in the right direction.

 

 

An additional coating of RTV on the mating surface between the main cap and the cylinder block is also a good idea to avoid leaks.

 

This 351C buildup will utilize top-of-the-line performance parts that compliment one another in combination. A Cloyes True roller timing chain with multi-indexed lower sprocket allows the camshaft timing to be advanced or retarded as necessary.

 

Performance Tip

We are we taking advantage of modern camshaft technology and profiles by upgrading to this Crane hydraulic roller with stud-mounted roller rocker arms. The result will be less friction, less wear, less heat, and better performance.

 

Liberally coat the camshaft with the recommended assembly lube to ensure proper break in and longevity. The lube goes not just on the cam lobes, but on the distributor drive gear as well.

 

The Cleveland is really starting to look like something at this point. Custom pistons will aid both power and efficiency as part of a well-thought-out combination of parts.

 

This low-pressure test spring in place to help test the valvetrain geometry. Special springs for this task are available from aftermarket camshaft manufacturers such as Comp Cams (part number 4758-2).

 

Special Tool

Valvespring height is verified using a height micrometer. This step is more advanced and done in the machine shop when aftermarket valvesprings are being used. Manufacturer’s of aftermarket performance camshafts and valvesprings include a recommended installed spring height, which needs to be set during assembly. If the assembled height of the spring is too high, the face of the cylinder head where the valvesprings seat can be machined deeper or valves with longer stems may be installed. If the checked spring height is too short, shims of various thickness, as shown here, are placed under the base of the springs to bring them up to specification. Spring height can also be adjusted by installing of spring retainers and keepers with different offsets.

 

The open and closed spring rates are checked on this device to ensure that they meet advertised specifications.

 

Performance Tip

The Crane stud-mounted roller rocker arms being used in this engine utilize a positive lock for accurate lash settings on the valves. There are two types of rocker mounts with Cleveland engine. With the pedestal mount, used in all hydraulic valve applications from the factory, the rocker is simply torqued into place. This head also features an alignment ridge in the spring seat. This setup is ideal for simplicity and lower-performance applications. But adjustable rocker arms are more desirable when machining heads or building higher-rev engines. Some factory performance Cleveland heads, such as the Boss 351 head, as well as aftermarket heads, have this fulcrum machined flat for screw-in studs, as well as machined valvespring seats for performance multi-coil valvesprings. Make sure when planning your build that you have the right valvetrain parts for your heads.

 

A Little History

The 335 engine series, of which the 351C is a part, includes features found on Ford’s small-block engines (289/302/ 351W) as well as big-block (429/460) engines. And to make matters even more confusing, Ford built the true small-block 351-ci Windsor during the same time frame as the Cleveland.

The 351-ci Cleveland, named for the Cleveland engine plant, was developed in 1969, first appeared in 1970, and lasted until the 1974 model year. The new engine shared its canted-valve, poly angle combustion-chamber cylinder-head design with the 429/460, while retaining the engine mount locations and bell housing bolt pattern of the small-block. (Canted valves are splayed at an angle, rather than in-line. This improves airflow.) The 351C differs from the 351-ci Windsor in that it has an integral timing cover cast into the cylinder block instead of a stamped cover. The thermostat is located in the block as opposed to the intake manifold as on the 351W, and as a result, coolant was routed from the cylinder heads, through the block, and then into the radiator for improved cooling. The most apparent difference between the two 351s is the canted-valve cylinder heads found on the Cleveland.

 

Boss 351

Sadly, the performance era at Ford came to an end within one year of the introduction of the 351C engine. Government regulations and the insurance industry put the brakes on high performance offerings from Detroit, and it would be a decade before another exciting car came out of Dearborn. Ford’s last hurrah in the high-performance car market was the Boss 351 Mustang. The Boss 351 was not highly advertised and pretty much slipped beneath the radar, though it was arguably one of the quickest Mustangs in stock form ever built. Available only in 1971, there were just 1,806 Boss 351 Mustangs produced.

The “Boss” in Boss 351 was provided by an honest-to-goodness, purpose-built high-performance version of the 351C engine. Based on the 4-bolt-main Cleveland block, the Boss’s high-nodular iron crankshaft swung a set of connecting rods that had received the hot rod treatment (Magnafluxed and shot-peened) and a set of forged-aluminum pistons. The canted-valve, quench-type cylinder heads with 64.6- to 67.6-cc combustion chambers provided a compression ratio of 11.1:1. A 750-cfm model 4300D Autolite spreadbore 4-barrel carburetor gulped fresh air via a special ram air hood and sat atop an aluminum intake manifold. With a solid-lifter camshaft bumping the valves, the Boss 351-ci produced an honest 330 hp at 5,400 rpm and 370 ft-lbs of torque at 4,000 rpm.

And while the Boss 351 was a stand-alone model of the 1971 Mustang sports roof, the 429-ci Cobra Jet and Super Cobra Jet engines were an option in all Mustang models for the year and these are even more rare than the Boss 351. The 429-ci SCJ/Drag Pack option, while available in the Mustang for 1971, was not  offered in the Torino after 1970.

 

351M and 400

Ford saw a need for an engine that was more efficient than the 385 series, but produced more torque than the existing small-block. The answer was the 400, also referred to as the “400M” for modified, in 1971. Based on the 351C, the 400 block featured a deck height that was 1 inch taller than the Cleveland in order to accommodate its 4.00-inch stroke. The 400 is considered a “square” engine because its bore is also 4.00 inches. The 400 actually displaces 402 ci, giving it the distinction of being Ford’s largest displacement small-block, as well the last pushrod design engine developed by the company. It also boasts the longest stroke of any Ford V-8 engine. With great lowend torque and 20-percent less weight than the 385 series, the 400 was a good compromise engine, and it powered full-size and midsize passenger cars and light trucks until 1982.

 

335 Series Parts Interchangeability

As with many other Ford engine series, the engineers at Dearborn apparently felt that the waters weren’t quite muddied enough by displacement variety and outwardly similar appearances of the 351C, 400, and 351M engines. So they managed to include some differences that prevent a universal parts interchange across the series. Learning the differences between the three engines is handy, but you’ll still need to learn which parts interchange and which will not. I have already  noted the difference in deck height between the 351C and the 400 and 351M so no further discussion is required on that topic. The following is more relevant information.

 

Cylinder heads: All 335 series engines share the same bore diameter, bore spacing, head bolt size and location, and water jacket passages, so all the heads can be interchanged. The 4V heads have much larger ports, and will have “4V” cast into them.

 

Intake Manifolds: 2V and 4V engines have dramatically different port and valve sizes. The 2V and 4V intakes will not interchange. Aftermarket intake manufacturers will specify application as long as you know which cylinder heads you have.

 

Crankshafts: The 400 and 351M have a larger main-bearing journal diameter and thus their cranks will not interchange with the 351C.

Camshaft and timing set: All 335 series engines have the same crankshaft-to-camshaft dimension and block front design, making these parts interchangeable.

 

Valve lifters, rocker arms, and pushrods: While the valve lifters will interchange, the pushrods will not, due to the different deck height between blocks. The rocker arms on engines utilizing nonadjustable hydraulic-lifter valvetrains will interchange, while those for solid-lifter engines will not. All 335 series rocker arms are 1.73:1 ratio.

 

Valves: The 351C 2V cylinder head and the 351M share the same valves, but in order to use the larger 351-ci 4V valves, the 351M cylinder head would require modification.

 

Pistons: While the 351C and the 400 engine share similar compression height (the distance between the wrist pin and the top of the piston), the 400 has a larger wrist pin. The 351M has a  taller compression height, so the pistons are not interchangeable with the other engines in the series.

 

Other: Parts such as the distributor, fuel pump, thermostat housing, oil pump and pan, and water pump are interchangeable throughout the series.

 

What is Valvetrain Geometry?

To many, the term “valvetrain geometry” conjures up visions of a black art practiced only by those engaged in building all-out competition engines. But in actuality, getting the valvetrain geometry right is important on any overhead-valve engine, since it not only ensures that maximum power is delivered in the most efficient fashion, it also protects vital engine parts against undue The 335 engine series, of which the 351C is a part, includes features found on Ford’s small-block engines (289/302/ 351W) as well as big-block (429/460) engines. And to make matters even more confusing, Ford built the true small-block 351-ci Windsor stresses, wear, and potential failure. In other words, if the valvetrain geometry isn’t right, your engine  could lose power and break parts—that should be enough to get you interested even if you don’t plan to go racing.

First let’s discuss the theory behind valvetrain geometry. When the lobe on the camshaft comes up and moves the valve lifter toward the top of its bore, a pivoted lever (the rocker arm) causes the valve to open. The goal is to do this with the least amount of wasted motion by trying to align the midpoint of the pushrod’s travel with the tangent point (rotational center of the rocker arm).

So how do you achieve this? First, we need to discuss the factors that will cause variations in valvetrain geometry. Even though in most cases you would be safe to assume that the factory engineers who designed your engine worked out the geometry, things may well have changed. How, you ask? Processes as seemingly mundane as machining the deck surfaces of the block or cylinder heads can create changes in valvetrain geometry.

But can the average backyard mechanic check valvetrain geometry without a bunch of sophisticated tools? Yes, and the only special tool required is an adjustable-length “checking” pushrod.

The steps are simple. Step one: If your engine is equipped with hydraulic valve lifters, you will first have to install a solid lifter in the lifter bore of the cylinder being checked. Color the tip of the valve using a black marker. Step two: Install the checking pushrod (set to the length of the OE pushrod) and a rocker arm. Set the rocker arm to zero lash. Step three: Rotate the crankshaft in its normal direction of rotation through two or three complete revolutions. Now remove the rocker arm and look at the pattern left by the tip of the rocker arm on the valve.

If the geometry is correct, the pattern should be narrow and centered on the tip of the valve. If the pushrod is too long, the pattern will be wide and off center toward the exhaust (outside) of the valve tip. If the pushrod is too short, the pattern will be toward the intake side of the head. Correcting this misalignment is a matter of adjusting your checking pushrod (either longer or shorter according to the pattern on the valve tip) and repeating the process until you get the pattern right.

From this point, you have the option of requesting that your machine shop accurately measure the length of your checking pushrod using specialized tools, or you can pack the measuring pushrod off to your chosen aftermarket pushrod supplier and purchase a set of rods made to this length. Either way, when your engine goes back together, you can be confident the valvetrain is geometry correct.

 

The long block has been masked off and primed in preparation for a final coat of Ford engine blue.

 

Performance Tip

A windage tray has been fitted to the main bearing cap studs. This part keeps the crankshaft from “dragging” in the oil and is an inexpensive way to gain horsepower.

 

Performance Tip

This performance buildup includes a deep-sump Milodon oil pan, and as a result, an extended pickup must be attached to the oil pump. At right is the ARP oil pump drive that will replace the stock Ford part. A good pump drive should be considered for any Ford engine rebuild, performance oriented or not.

 

The depth of the oil pan sump is double-checked to ascertain the clearance between the pump pickup and the floor of the pan.

 

This is a fine example of what a strong 351C bottom end should look like. The 4-bolt main caps with studs, windage tray, extended pump pickup, and SFI-approved damper are shown.

 

On top, a Crane hydraulic-roller camshaft and studmounted roller rocker arms bump the poly-angle valves in the 351C 4V cylinder heads.

 

Here’s a view from below with the Milodon deep sump oil pan in place. A chrome fuel pump replaces the OE part.

 

Performance Tip

This performance Cleveland will utilize an Edelbrock aftermarket aluminum intake. Some grinding will be necessary to match the Cleveland’s huge intake ports. The manifold has been scribed with the intake port outline to match the cylinder heads.

 

Special Tool

A high-speed grinder quickly removes the aluminum from the aftermarket intake manifold. The openings are blended down into the runner to ensure a smooth transition for the air/fuel mixture.

 

The port on the right has been matched, while the one on the left waits its turn with the grinder. Care must be taken to remove all grindings from the intake manifold before it is installed on the engine.

 

With port matching and a thorough cleaning out of the way, the Edelbrock Performer Air Gap intake manifold is ready for installation.

 

This Cleveland will run as good as it looks with the aluminum intake, a high-efficiency Edelbrock aluminum water pump, polished valve covers, chrome fuel pump, and dip stick.

 

Performance Tip

A high-pressure braided line has been tapped into the main oil feed to carry lubricant directly to the gallery at the back of the block. Though oiling-system upgrades are essential for racing engines, they are not necessary for standard use.

 

The completed 408-ci Cleveland long block awaits installation in Lee Lundberg’s beautiful 1970 Torino.

 

Lee’s Cleveland is looking great with the engine bolted in, all accessories installed, and lines and wires in place. The Cleveland will breathe fresh outside air through the factory shaker scoop as it powers the Torino to car shows and cruises.

 

During its relatively short life span, the 335 series (the 351C in particular) proved very versatile and was used to power a wide range of Ford and Mercury passenger cars and light trucks. Of all the models equipped with the 351C, the Mustang featured the widest variety of possible combinations, including a highly specialized performance version known as the Boss 351 built only in 1971. This 1973 Mustang is fitted with a more mundane version of the Cleveland that, while still topped with a 4-barrel carburetor, had been de-tuned with lower compression and a milder camshaft grind to meet the ever increasing emissions standards. (Photo by Colin Date from the archives of Legendary Ford Magazine)

 

351C Performance Cylinder Heads

For an engine series with a relatively short life span, the 351C has done more than its share to make a mark in the world of motorsports competition. Along the way, it has garnered enough fans to justify the performance aftermarket developing of parts to keep them racing.

There was a time when the 1970 to 1971 4V 68-cc closed chamber OE cylinder heads, with their 2.19-inch intake and 1.71- inch exhaust valves, were considered the hot setup, as the Boss 351 head was just too rare for general use.

With all their strong points, the 4V Cleveland head had one glaring drawback that at first glance does not appear as such. These heads have intake ports that are large enough to be called “cavernous.” While large intake ports are great in the upper RPM range, they aren’t so great down low, providing a narrow powerband that is detrimental for street performance.

The last closed-chamber Cleveland cylinder heads were cast in 1972, and while they shared valve sizes with the early castings, the combustion chambers grew to 75.4 cc. The future for 351C looked bleak.

But then hope came from the most unlikely of places and it would not be from the aftermarket. Our friends down under found the design of the 335 series Ford engine much to their liking. In true Aussie fashion, they added a little of their own magic to the combination, reducing the displacement to 302 ci, which in turn called for a redesigned cylinder head. It did not take long before the new cylinder head was discovered here and became coveted by American performance enthusiasts, who christened it the “Australian Cleveland head.”

The Australian Cleveland cylinder head is a new combination of a number of characteristics found in different 335 series heads. The Australians combined the smaller 2V-size intake port with 58-cc closed combustion chambers filled with the larger 4V-sized valves. The Aussie head became the ultimate street performance cylinder head available for the Cleveland at the time.

Since that time the Australia based aftermarket company AFD has developed aluminum cylinder heads for the 351C in both 2V and 4V intake port configurations. The AFD 4V head features 57- to 64-cc closed combustion chambers with 2.19- inch intake and 1.71-inch exhaust valves. These heads flow 298 cfm on the intake port and 205 cfm on the exhaust side at .500 inch of valve lift. The 2V version of the head has 60-cc chambers, 2.05-inch intake and 1.65-inch exhaust valves and delivers 290 cfm on the intake and 217 cfm on the exhaust side at .500 inch of lift.

Ford eventually cast its own high-performance version of the 351C head in aluminum (PN M-6049-A3) but these heads have since become unavailable.

Blue Thunder, a long-time producer of cylinder heads for Ford products, has an all-out racing version of the Cleveland head patterned after the current style of head used on Ford NASCAR engines. This head fits both Cleveland and Windsor cylinder blocks. Available with valve sizes from 2.02 to 2.20 inches on the intake and 1.60 to 1.70 inch on the exhaust, the Blue Thunder head also boasts the Yates exhaust port, named for its designer and legendary Ford racing-engine builder Robert Yates. Since these heads are designed for use in racing competition only the, flow numbers are all listed at .700 inch of valve lift and higher. These heads would not be compatible with an engine built for street use.

Edelbrock, who started casting heads for Fords over five decades ago, is also now making some great Cleveland heads. The new Edelbrock head (part number 61629) sports a tight 60-cc combustion chamber fed by 2.05-inch intake and 1.60- inch exhaust valves. Flow numbers at .500-inch lift—267.9 cfm on the intake and 160.8 cfm on the exhaust—are very impressive for a head primarily designed for high-performance street use. Edelbrock has also developed a version of its successful Air Gap intake manifold to go along with the new heads. Modified Mustangs and Fords magazine reports 450+ hp plus Dynamometer readings from a Cleveland using the new heads and intake combination.

CHI, or Cylinder Head Innovations, is the latest aftermarket company to jump in with an aluminum 351C cylinder head. CHI makes a variety of heads for the Cleveland engine, some of which are winning awards such as the Engine Masters Challenge.

If you look closely at the engines being used in NASCAR competition by the Ford teams, you can’t help but note the Cleveland-style cylinder head on top of the Ford Racing Windsor block. Even Chevrolet has adopted a canted-valve cylinder head with port spacing that looks suspiciously similar to the Cleveland for its NASCAR engine. As they say, imitation is the sincerest form of flattery.

With continued interest from competitors and continued parts development through the aftermarket, I hope to see the Cleveland bad boy around for quite a while.

Written by Charles R. Morris and Republished with Permission of CarTech Inc