Ford 351C Tuning

"All you need to know about tuning and performance parts on the Ford 351C engine!"

One engine that keeps cropping up in emails and questions we get sent, is the 351C, and what modifications work best on it. So this guide has been assembled from comments, posts, feedback and conversations with owners to take you through what we feel are the main modifications and areas that you should tune and outline which modifications we feel are the best.

The Ford 351 Cleveland was a V8 engine that was offered between the years 1969 and 1974 and belonged to Ford’s famous 335 family.

The numeric figure of 351 exists in the name because of their 351 cubic inch displacement, cylinder head bolt pattern, and bore spacing. These 351C engines were developed with high performance in mind.

Our aim here is to consider 351C tuning and outline the best mods that work. A Ford 351C is awesome to work on and with carefully picked motorsport tuning mods like turbo upgrades and camshafts, you will enhance your driving opportunities.

See our video which provides a complete introduction to Ford Tuning, it contains some tips on performance and handling modifications.

History of the 351C Engine

The Ford 351 Cleveland engine came into existence when the engine demand became so high that the previously operational Windsor facility was unable to meet it.  However, the growing environmental concerns led to their end by 1974.

So, why are these engines referred to as Cleveland? The manufacturing plant was located in Brook Park, Ohio which is a Cleveland suburb, hence the name.

Categories Of Ford Cleveland Engines All Ford 351 Cleveland engines could be broadly classified into two categories:

  • 351C-2V 2 venturi version;
  • 351C-4V 4 venturi version.

The 351C-4V was considered the performance version engine.

Engine Codes & Types The engines were launched with different codes:

  1. H-Code;
  2. M-Code;
  3. R-Code;
  4. Q-Code.
  • 351 Cleveland
    351 Cleveland started manufacturing 4V big port heads with closed "quench" combustion chambers in July 1969 for the 1970 model year. Categories Of Ford Cleveland Engines All Ford 351 Cleveland engines could be broadly classified into two categories:

    • 351C-2V 2 venturi version;
    • 351C-4V 4 venturi version.

    The 351C-4V was considered the performance version engine.

Engine Codes & Types The engines were launched with different codes:

  • H-Code;
  • M-Code;
  • R-Code;
  • Q-Code.

Explanations of the differences between them.

  • H-code 
    Cleveland engines with the H-code 351 were low-performance engines with low compression ratios and two-barrel carburetors.
    The H-Code engines were produced between 1970 and 1974 and were relatively low-performance variants. All H-Code Cleveland engines used small port 2V heads. It is worth noting that the H-Code Ford 351 Windsor engines were also produced during the same era.
  •  M-code
    In 1970 and 1971, M-code was a high-compression, high-performance variant of the 351C. The M-Code was designated for high-performance engines that were produced from 1970 to 1971.
  •  Boss 351 1971R Code
    The Boss 351 was the 351C's most powerful high-performance variation, offered only in the 1971 Boss 351 Mustang. Rated at 330 horsepower The R-Code Ford 351 Cleveland engine was the best performing variant out of all.
  • Boss 351 1972R Code (351C HO)
    This was a tweaked variant of the 1971 R-Code and was launched because of emission constraints
    In comparison to the 1971 Boss 351 "R-Code," the 351C HO "R-code" had a number of adjustments to assist satisfy 1972 emission requirements.
  •  Q-code 351 
    From May 1971 until the 1974 model year, the Q-code 351 "Cobra-Jet" (also known as 351-CJ, 351-4V) was manufactured. This was also a high-performance engine.

Tuning the Ford 351C and best 351C performance parts. Here are some of the modification upgrades for the Ford 351 Cleveland engines:

Best 351C mods

The ultimate 351C parts on an engine are in our opinion the ones that give the best value for money.

We won't be swayed by popular 351C parts, they need to be cost effective.

Please watch our video which covers the 5 principles of tuning your 351C. Be sure to keep up with our latest YouTube content and subscribe.

Best mods for your 351C

  1. Lighter flywheels - a lighter flywheel will improve the engines ability to rev freely. But not always suitable for all 351C engines.
  2. Forced induction upgrades - Adding a turbocharger is the most significant way to raise the intake air supply, which permits you to use more fuel and make more power. It is one of the most technically difficult mods but provides the best gains.
  3. Fast road Camshafts are are often the best upgrade for an engine, but they must be setup by someone who knows what they are doing and they are not always easy to source but you might find a local firm to regrind a stock cam.
  4. Upgrades to fuel injection, this allows much better control over fuelling and helps when adding forced induction upgrades.
  5. Intake and Sports Exhausts - NB: on their own these mods will NOT ADD POWER , but they can help lift power after other mods by losing a restriction.
  6. Flowing and porting the Head - Head work will get air flowing into the engine while removing turbulence or restrictions.

351C Tuning Stages

Typical stage 1 mods often include: Panel air filters, Drilled & smoothed airbox, Remaps/piggy back ECU, Sports exhaust manifold, Intake manifolds, Fast road camshaft.

Typical stage 2 mods often include: Sports catalyst & performance exhaust, induction kit, high flow fuel injectors, fuel pump upgrades, Fast road cam, Ported and polished head.

Typical stage 3 mods often include: Competition cam, Crank and Piston upgrades to alter compression, Internal engine upgrades (head flowing porting/bigger valves), Adding or Upgrading forced induction (turbo/supercharger), Twin charging conversions, Engine balancing & blueprinting.

Camshaft Upgrades

Getting a fast road cam will work better at upper RPM range power and are better suited on gasoline engines, than diesels. In most cases you will see top end power hikes through performance camshafts on most engines

The camshaft profile plays a big part in the engines power output so camshaft upgrades make quite a large difference. The intake and exhaust durations will alter depending on the chosen camshaft profile, so large power band gains are on offer for camshaft upgrades.

Fast road camshafts normally boost the torque throughout the rev band, you may lose a little bottom end power but higher rpm power will improve.

Motorsport camshafts, boost the higher rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.

For a daily driver you should ideally to match your power band to your usage of the car.

A camshaft is another important part of an engine that greatly affects its performance.

Upgrading the camshaft of your Ford 351 Cleveland engine is a sure shot way to get higher performance figures.

Edelbrock Performer Plus Camshaft Kit The Edelbrock Performer-Plus Camshaft Kit is great in that it has been designed for high-performance street applications.

The kit costs around $350 meaning that it is one of the relatively low priced parts that you can put on your Ford 351 Cleveland engine to improve the output.

This kit provides impressive power from 1500 to 6500 RPM. The best part of this kit is that it has been designed in a way that ensures high RPM horsepower while also providing moderate torque at low RPMs.

Hydraulic Roller Cams Another relatively inexpensive yet effective method for getting more power from your 351 Cleveland is by using aggressive hydraulic roller cams.

Comp Cams offer a great part known as Magnum 224/224 Hydraulic Roller Cam for Ford 351C, 351M-400M. This is the ideal part if you are looking for street performance over 3500 RPM. At a price of around $400, the performance it delivers is the best value for money.

Using High-Quality Stud Kits High-quality studs like the ARP Cylinder Head Stud Kit Hex Head 351C/351M/400 are also great if you are trying to rebuild your 351 Cleveland engine. These heads ensure that you get peace of mind while working on improving your car’s performance.

These are likely to set you back around $200 and deliver exceptional quality.

Tips To Improve The Performance Of a 351 Cleveland

It is vital to realize that before you go on buying new stuff for your vehicle, you must first utilize all the existing components in the best possible manner.

This means that if a part isn't performing as well as it should, it might just need a little tweaking before you go out and spend hundreds of dollars on it only to discover that the one in your car is already well suited for great performance.

Different 351C engines respond differently primarily due to the airflow when camshafts are fitted depending on the camshaft being more extreme camshaft durations and cam profile as unique due to manufacturing tolerances and quality variations so check your engine on a rolling road.

The ECU mapping and fuelling and fuel pump also have a large bearing on the power gains you'll make.

A longer valve duration can adjust the power curve, and on most engines there are some advantages to extending the intake or exhaust durations and valve lift.

The 351C units are fantastic to work on and we note that there is a growing number of modifications and tuning parts out there.

ECU Mapping Improvements

ECU flashing allows a tuner to fully realize the full potential of all the upgrades you've installed on your 351C.

(Sometimes chip tuning the ECU is not an option, so an aftermarket ECU is the route to take, and most of these exceed the specs and performance of your factory ECU's but ensure it has knock protection and that you get it installed right.)

It will usually give around 30% more power on turbocharged vehicles and you can expect to see around 15% on NA (naturally aspirated) engines, but the outcome often differs on the upgrades you've carried out and the condition of your engine.

351C Intake Mods

It is the goal to any engine performance tuning project to push fuel and air into each cylinder

Air Intake manifolds flow the air from the air filter and allow it to be sucked into the engine and mixed with fuel.

Air intakes are the most pivotal component of any vehicle modification project and has a direct bearing on how much fuel can be used.

The reputation for performance increase due to these air intakes is so substantial that they are normally the first part that most enthusiasts upgrade. The reality is that on stock engines with few other mods you'll be hard pressed to see 4-7% more top end power.

An air intake increases the flow of air to the engine. When this air is mixed with fuel, it leads to a higher combustion rate. This improved ability for combustion generates more power and torque which increases the performance of the vehicle.

Edelbrock Performer 351 Intake Manifold

The Edelbrock Performer 351 intake manifold is a great upgrade for the Ford 351 Cleveland. However, this part won’t fit the R-Code 351C engines.

Performance Air Filters Air filters play a vital role in providing fresh clean air to the car’s engine. However, as most air filters block a majority of the air passing through them, they can often be the cause of reducing the performance of your car.

The K&N E-1560 High Flow Air Filter is the best fit for your vehicle with the Ford 351 Cleveland engine as it not only ensures that the air getting inside your vehicle is clean but also makes sure that the engine gets an adequate supply of air for combustion.

The price of $160 might seem a bit too steep for an air filter but the performance boost makes up for the huge price tag.

Shape and flow rate of the Plenum can make a noticeable improvement to fuel engine efficiency on the 351C.

It's not uncommon that intake manifold are needing an upgrade, although some car makers provide reasonably well designed intake manifold.

Fitting big valve kits, doing some port matching and head flowing will also boost performance, this will allow you to get a greater performance increase on other tuning mods.

351C Turbo upgrades

NA (naturally aspirated) engines need quite a lot of work when you add a turbo, so we have a separate guide to help you take into account the pros and cons of going this route on your 351C

The more air you can get into an engine, the more fuel it can burn and uprating the induction with a turbocharger upgrade makes major power gains. Like all other engines, adding a turbocharger to a Ford 351 Cleveland increases the airflow to the engine.

The turbocharger makes use of exhaust gases to run the turbine. After this, the compressor connected to the other end of the turbine also starts rotating which reduces the air pressure. This gulps in more air which is then supplied to the Ford 351C engine leading to higher power and torque.

If your motor has a turbocharger parts are more reliable and most turbo charged engines use harder and stronger components.

There are practical limits for every engine, with some being extremely strong and some only just able to handle stock power. We recommend you find these limitations and install better pistons and crank to survive the power.

It's not unheard of guys spending lots of money on turbo upgrades on the 351C only to experience the engine explode soon after it's finished.

Large capacity turbo chargers often suffer a bottom end lag, and small turbo chargers spool up more quickly but won't have the peak end power band gains.

In the last 10 years the range of turbo units is always evolving and we now see variable vane turbo units, allowing the vane angle is altered according to speed to lower lag and increase top end power.

Twin scroll turbo units divert the exhaust gases into 2 channels and direct these at differently angled vanes in the turbo. They also increase the scavenging effect of the engine.

Supercharger Upgrades

Another great way of improving the power and torque of your 351C engine is to supercharge it. What supercharging does is that it provides an accelerated means of supplying more air to your vehicle’s engine.

However, the difference from the turbocharger is that in this case, the engine is provided fresh natural air that is rich in oxygen.

Torqstorm Ford 351 Cleveland Twin Supercharger Kit

A great option in this regard is the Torqstorm Ford 351 Cleveland Twin Supercharger kit. Although the part costs around $7000, the performance gains are extremely impressive which justify the high price.

Such kits can provide a performance boost of around 40% to 50% and the power of the vehicle can be raised to as much as 700 hp.

Upgrade the Air sensor

You'll commonly see there is a limitation in the air flow sensor AFM/MAP on the 351C when loads more air is being pulled into the engine.

Going up you'll find 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor limited torque at a much lower level.

Adding a supercharger or additional turbo will make large bhp and torque gains, although more complex to install. We have this feature on twinchargers if you want to read more.

Fuelling Upgrades

When you lift the bhp you will need to increase to the fuelling.

More bhp needs more fuel. Fuel pressure boost valves raise the fuel pressure, providing a more snappy throttle response.Most tuners we speak with say to over specify your injector capacity.

The accepted safe increase is to add another 20% when buying an injector, this allows for injector deterioration and affords you some spare capacity should the engine require more fuel.

Injection Kits

Injection kits have a huge role in determining the performance of an engine. An improper injection system can even choke a high-performance setup.

This is why choosing the right injection kit for your Ford 351 Cleveland engine is vital. A proper fuel injection system can improve the performance of your vehicle easily by 10% to 15%.

Here are two particularly great upgrade options.

Pro-Series Ford 351 Cleveland V8 Stack Injection Kit

This kit can be used for the 2V options however you need to keep in mind that the part is quite expensive and can cost you around $5000.

It can easily support up to 580 to 600 hp.

E-Series Ford 351 Cleveland IDA Quad Stack Ignition

This injection kit is another great option with the added benefit that in addition to the 2V options, it can also be used for the 4V variants. Similar to the first option, even this kit can support up to 580 to 600 hp.

Fuel Pump The fuel pump of a car is another major improvement that can drastically affect the performance of your car. One great example in this regard is the Robb Mc Performance 1020 mechanical fuel pump.

It is special in that it has been designed to work ideally up to 550 hp.

We think this one is common sense, but you'll need to match your fuel injector to the type of fuel your car uses as well.

351C Performance Exhausts

Only look to uprate your exhaust if your current exhaust is creating a restriction in flow.

On most factory exhausts you'll find the exhaust flow rate is still ok even on modest power gains, but when you start pushing up the power levels you will need to get a better flowing exhaust.

Do not go with the largest exhaust you can source you'll slow up the exhaust flow rate - the best for power gains are usually between 1.5 to 2.5 inches. It is the shape and material more than the bore size.

For road going cars mods such as a sports catalyst pretty much remove this restriction,mainly due to it's larger size and surface area, and will effectively raise the performance to levels you would expect without having a catalyst installed.

This keeps the car road legal and will allow the full exhaust flow due to it's higher internal surface area and design. The alternative decat or catalyst removal should be considered an off road only mod, as removing a catalyst is illegal in most territories and regions for road registered cars (and in some you can't even replace a working catalyst).

Exhaust Upgrade tips

Performance exhausts are great in that they not only improve how a vehicle performs but also provide aggressive sound.

Besides this, a performance exhaust system also reduces the back pressure which means that more hot air can leave the vehicle allowing the engine to perform optimally for extended periods.

However, not everything works with the Ford Cleveland 351C.

This is why knowing what to get is vital.

Going for the Pacemaker Tri-Ys is a great option. The Falcon XR-XF & Fairlane ZAZL 351C 4V TRI-Y in particular is a great option.

The fitting time of this system is around 3 hours which makes it a fairly reasonable upgrade.

Exhaust Header If you are looking for upgrading the exhaust header of your Ford 351C, the Patriot Exhaust H8435-B Clippster Header, Street Rod, Universal 351C is the way to go.

Weak spots, Issues & problem areas on the 351C

The 351C engines are fairly reliable as long as they are well maintained.

Carbon build up in the head, particularly around the valves which will sap power or create flat spots, this is a larger issue on direct injection engines but should be looked out for on all engines. We have tips on intake clean to remove carbon build up By avoiding short journeys where the engine doesn't warm up and using good quality fuel you can reduce this risk.

Frequent oil changes are vital on the 351C, and more so when the car is modified and will help extend the life and reliability of the engine.

If you want to learn more, or just get tips on Tuning your 351C engine please join us in our friendly forum where you can discuss 351C tuning options in more detail with our 351C owners. It would also be worth reading our unbiased Ford tuning articles to get insights into each modification and how effective they will be.

Please help us improve these tips by sending us your feedback in the comments box below.

We love hearing what our users have got up to and which modifications work best for them on each model of car. We use your comments and feedback to improve the accuracy of these 351C tuning guides which get regular updates and revisions.

Please Check out my YouTube channel, we're regularly adding new content...

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