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351w Small Block Ford Specs, History, and Identification

What follows is most of the research I’ve done on the 351 Windsor (351w) in preparation for swapping it into my truck.  Keep in mind that I gathered almost all of this information from places on the internet and none of it is personal experience… because I don’t have any.  That said, I’ve tried very hard to fact check and verify my information as best as I can. I hope that this information put together in one place is useful for anyone looking for more details or thinking about swapping or building this SBF (Small Block Ford) engine.

What is a 351 Windsor Exactly?

351 Windsor Small Block Ford Engine
351 Windsor Small Block

The 351 Windsor (351w for short) is the largest of the Ford Small Block engine family. Ford Motor Company built them between 1969 and 1996.  It’s a 90 degree V8 with an overhead valve train. The 351 corresponds to the number of cubic inches displaced by the stoke of all 8 cylinders during normal operation.  It’s also commonly referred to as the 5.8 liter for the same reason.  The name ‘Windsor’ comes from where the engine was produced… in Ford’s Windsor Ontario casting plant. 

Similar in size and shape to the very common 302, the 351 is a taller block. This allows for more piston travel in the cylinder, increasing the cubic inches.  To accommodate the increased displacement and increased power, the 351 block castings are beefier in almost every respect.   

The Windsor is one of three engines offered by Ford in the 351 displacement.  There was also the 351 Cleveland and the 351M (often called the ‘Modified’).  The Windsor engine is by far the most common and had the highest production numbers… Ford produced about 8.6 million units at the Windsor plant.  It also tends to be the easiest to find aftermarket parts for, due to it sharing many parts with the 302 small block.

351 Windsor Stats and Measurements

The 351 Windsor has a displacement of 351 cubic inches or 5.8 liters.  The stock stroke of the engine is 3.5 inches and the stock cylinder bore is 4 inches.  It has a distinct firing order from the other Ford Small Blocks, 1-3-7-2-6-5-4-8 vs 1-5-4-2-6-3-7-8.  Cast out of iron, the bare block weighs in at between 150 – 200 lbs depending on the year. Blocks older than 1974 are heftier by 25-30 lbs due to having more metal in the casting.  Prior to 1971 the deck height reached 9.48 inches, and after 71 it changed to 9.503 inches… Something to make note of if you’re rebuilding one of these engines since the deck height will affect the compression ratio and the valve / piston head clearance.

The stock engine uses 2 bolts to secure the main bearing cap to the saddle, known as two bolt mains.  Stock, the compression ratio was around 11:1 in 1969. Emissions restrictions caused the ratio to move as low as 8.8:1 in later years.

Early 351w engines produced a maximum of 300 horsepower and found their way into Mustangs, Galaxies, Cougars, Country Squire Station Wagons, Fairlanes, and Torinos.  Later years were also installed into trucks, vans, and marine applications.  Later engines had lower horsepower numbers and higher torque numbers as a result of vehicle requirements and emissions. 

351 Windsor History

Casting Issues

Ford Windsor Casting Plant
351 Windsor Casting Plant

Ford began casting the 351 Windsor in 1969 and produced them up until 1996. Prior to 75, blocks were cast using green sand molds and pneumatic packers or vacuum pressure. These methods worked well, but caused some issue with mold core shifting. This meant that Ford required more material in the block to meet minimum specifications. After 74, Ford used better molding techniques, eliminating the need for the extra material. While true that newer blocks are ‘weaker’ than older blocks because of the material deficit, 351 blocks are still the strongest small block available and should be able to handle any streetable horsepower numbers. Still, for this reason, builders sometimes covet 351w blocks from 69 – 74, looking for very high horsepower or torque numbers.

Modifications Throughout the Years

In 1971 Ford extended the deck height from 9.48 inches to 9.503 inches to lower the compression ratio for emissions.  In 74 they added a boss in the front right of the engine for an air injection pump.  Also in 74, the oil dipstick moved from the timing case to under the left cylinder bank.

Until 76 the block used 16 bolt holes for the intake manifold, but Ford changed it to 12 bolts from 77 onward. It should be noted that the 351 has larger head bolt holes than the 302. This means the same heads will fit, but a 302 head will need to be drilled out to accommodate this if it’s being used on a 351. A popular example of this is the GT40 head used on higher performance 302 engines being swapped into a 351 for higher flow numbers.

In 1983, Ford modified the rear main seal from the old 2-piece design to a more modern one-piece rear main seal.  Very late in the engine’s production, 1994, the design changed again to accommodate roller lifter and camshafts rather than flat tappet lifters and camshafts.  This change, only available in the final two years of production, makes these blocks highly sought after. Often these are just called F4 blocks due to the casting number or simply referred to as ‘Roller Blocks’.

351W Important Stats by Year

I put together this simple chart to help me identify the important features of 351 blocks by year. I can see at a glance what kind of a block I would get based on the year of the vehicle I pulled it out of.

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351W Vehicle Chart

Just as above, I put this chart together to give me an idea of what vehicles to look for. I regularly check Criagslist, Facebook Marketplace, or even junk yards to find the right block.

Print  CSV  Excel  Copy  

How to identify a 351w Casting Number

351 Windsor Casting Number F4TE
F4TE Casting Number on the Exhaust Manifold

The engine casting number is the best way to identify a Ford Small Block engine.   We can break down the beginning of Ford’s casting numbers into decade, year, vehicle or vehicle type, and engineering division.  A casting that starts with C90E was built in 1969 because the C signifies the 60’s and the 9 is for the last year of that decade.  The O signifies that it was built for a Torino and the E stands for Engine.  Castings that start with D are built in the 70’s, E in the 80’s, and F in the 90’s. 

My block is an F4TE, which means it’s a 1994 Truck Engine block. As I said before, F4 blocks are known as the ‘Roller’ blocks. That casting identifies them as having been built after 1994 when Ford switched to roller cam capable blocks.  Note that Ford didn’t install roller cams in all roller blocks from the factory. Many still utilize the old style flat tappet cams even though they are roller capable.

Windsor vs Cleveland vs Modified vs HO

Ford produced 2 (or 3, depending on who you ask) different 351 engines during the same time period; the 351 Windsor, and the 351 Cleveland.  Every now and then you’ll also hear about the 351M (also called ‘Modified’) or might even hear about the 351 HO or ‘High Output’.  What gives with all these different motors with the same displacement?

The Cleveland and the ‘Modified’ are both based on the same engine, which is entirely different from the Windsor.  They call it a Cleveland because Ford cast them in their Cleveland Ohio plant.  The Cleveland is part of the 335 big block engine family and was designed for more performance with better flowing heads and a stronger crank.  Physical differences include a recessed timing chain and 8 bolt valve covers vs the Windsor’s 6 bolt covers.  The bolt covers are the easiest way to tell if you’re looking at a Windsor or a Cleveland.

The 351M is closer to the Cleveland than the Windsor but is basically a de-stroked version of the big block 400, a different block altogether with a taller deck height than either the Windsor or the Cleveland (at 10.297).  The M also shares a bellhousing pattern with other members of the 335 big block engine family. The Windsor and the Cleveland both use a small block bellhousing pattern.

The 351 HO is just a Windsor engine with higher performance parts. It came with a 4-barrel carburetor and a larger cam.  Ford put HO engines in some trucks in the mid 80’s.

351 Windsor vs 302

The Ford 302 (5.0 liter) small block is in the same family as the 351, and it can often be hard to distinguish the two.  The 351 has a taller deck height and subsequently longer stroke, which accounts for the difference in displacement.  The 351 is also a heavier casting with more material, making it a stronger block overall.  The crank and rod journals are also larger in the 351, adding to crankshaft durability. 

Many of the parts for a 302 are interchangeable to the 351.  This includes heads, cam, lifters, water pump, engine mounts, timing chain, timing cover, and many other parts. As stated before, it should be noted that 302 heads have smaller bolt holes, so they’ll only fit a 351 if the holes are drilled out.  Earlier versions of the 351 (until 76) incorporated heads with more bolt holes and larger intake ports than the 302, though the exhaust ports always remained the same size.

The bellhousing bolts to both engines are also the same. This means a transmission that bolts up to a 302 will also bolt up to a 351. 

351 Windsor vs 302
351 Windsor vs 302 Distributor Mount

The firing order between the two engines is different, as is the oil pan, intake (due to the deck height difference), harmonic balencer (except pre 81 302’s which share the internal balance of the 351w), and distributor.

There are several ways to tell the difference between a 351 and 302 by visual inspection.  The easiest I’ve found is to look at the distributor mount height.  The mount will be near flush to the top of the block on a 302, while a 351 has the distributor mount sunk below the top of the block by around an inch.

Building a bigger Windsor (High Performance and Stroking)

351 Windsor blocks upgrade easily. A huge number of aftermarket parts exist for both the 351 and the 302.  Popular upgrades are the heads, since the stock 351 heads are mediocre at best, and other standard upgrade parts like the intake, cam, headers, and fuel delivery system.  While the latest generation of 351 Windsors typically generated around 180-220 horsepower from the factory, adding a new set of heads, a larger cam, and some other aftermarket parts can get a Windsor with the stock stroke to around 350-400 horsepower easily.

Stroking the engine by changing the crank and piston rods can increase the displacement to 383, 393, 408, 418, or 427.  Doing so makes horsepower numbers as high as 500 – 600 easily attainable. Even higher numbers are possible with the correct aftermarket parts or power adders.

Max horsepower?

The maximum horsepower attainable through a stock 351 Windsor is a matter of debate.  Most agree that 500-600 is easily and safely attainable without risking damage to even the later ‘standard strength’ blocks.  Earlier high strength blocks regularly reach 800 – 1000 horsepower without damage.  When it comes to cracking an engine block though, often it’s not the horsepower numbers but the sturdiness and quality of the parts and build that is most important.

Choosing a junkyard / oem block vs an aftermarket block

In my opinion, a junkyard oem block is a fine base to use for a 351 Windsor build provided you’re not planning on putting out more than 600 horsepower and redlining RPMs all the time.  Much more than that wouldn’t be streetable anyway.  If you really want to race the block and send massive amounts of power through it, then it might be worth your time to hunt down a pre-74 block for the higher strength. 

Purchasing an aftermarket 351 block can help you attain higher numbers without the worry of block failure.  1200 plus horsepower is not uncommon for an aftermarket 351 Windsor. Several reputable companies make aftermarket 351 blocks.

Why I chose a 351 Windsor

My 85 Bullnose houses a 300 six from the factory, but a small block engine option existed for my truck as well. Because of this, I know the small block form factor will fit without an issue, unlike a big block.  I wanted an engine that would bolt right into my Bullnose just to keep things easier for my first swap. The 300 six shares the same bellhousing bolt pattern as the small block engines as well, so I have the option to keep my transmission.  Engine mounting points between the 300 and small blocks are also similar with only the need to pull the mounts and perches from the donor and bolt them into the bullnose.  

I chose the 351 over the 302 because there’s no replacement for displacement. I’ve also read that the 302 is far easier to crack when running high horsepower numbers.  I’m not planning on getting numbers that high in my first build, but who knows where I’ll be down the road?  It’s also easier to get more horsepower for less money out of a 351, all else being equal, simply due to the larger displacement to start with.

Finally, the Ford Small Block platform has a vast array of parts and aftermarket support, meaning I can build the engine just about any way I want to. 

For more information about my truck, check out the rest of my site or my YouTube Channel!

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