What is the 351 W Engine?
The 351 Windsor (commonly referred to as the 351w) is just one of the many V8 engines that found their way into Ford vehicles in the decades of the 70s, 80s, and 90s. Named for the plant where it was made in Canada at the Windsor, Ontario plant. Ford made over 8.6 million of these power plants from 1969 - 1996.
The engine first debuted in the 1969 Mach 1 Mustang in both 2-barrel and 4-barrel carb configurations. (It had a max power stroke of 300 Horsepower and shared many components with the 289 and 302 Boss V8s developed a few years earlier.
The Ford 351 had a taller profile of 1.3 inches over the 302, and the 3” Crankshaft journals created more output to the cylinders than the smaller 2.25s in the 289 and 302. Ford resolved to use a cast iron block as a basis and cast the block with other metals to enhance the rigidity for a stronger block. (The pre-74 models of the Windsor were 25 lbs heavier than later models).
The Windsor eight-cylinder engine had a unique firing order from other V8s, which helped reduce noise and vibration. The initial offering in 1969 produced 250 HP @ 4600 rpm - 355 lb/ft torque @ 2600 rpm with a 2-barrel carburetor. The four-barrel carb generated 290 HP @ 4800 rpm and 385 lb/ft torque @ 3200 rpm, but it lasted only a year.
Eventually, the 351 Windsor would find its way into a host of other Fords, from the Galaxie, LTD, and Crown Vics, just to name a few. The motor powered the F150 truck for ten years (‘87 - ‘97) and the Ford Bronco for even longer (‘79 - ‘96). During the late 60s through the mid-90s, the engine was used in various vans and even marine applications.
How Many Different 351 Engines Were Made?
Ford Motor Company made three 351s. In addition to the Ford 351 Windsor engine, the 351C (Cleveland - so named for where it was built) and the 351M (Modified or Midland or Michigan - where it was made) followed the 351W. The Cleveland and Michigan models were based on the big block 335 engine family.
The Cleveland was flattened to sit broader and lower than the 351W, which made it ideal for racing and muscle car applications. The 351C stock engine found its way into the Mustang, Cougar, Montego, and Torino. For example, the 1971 Boss Mustang with the 351C generated a factory performance of 330 HP @ 5400 rpm and thrust the car down the track in 14.1 seconds for the ¼ mile. (A number that showed serious power while it gave much larger V8s a run for their money).
However, the C engine lasted only a few years until 1974 (when it was replaced with the more subdued 351M), and it is still a favorite for doing an engine swap among classic hot rod enthusiasts.
The 351M was a more moderate version of the Cleveland motor, designed to balance performance with efficiency. Ford began to realize that they needed an engine that didn’t suck fuel out of the tank every time you touched the accelerator. To solve this problem, the 351 M appeared in sedans and light-duty trucks.
How to Identify a 351W from a 351C or 351M?
There are a couple of ways to tell if you have a Ford 351 Windsor or a 351 Cleveland.
Valve Cover Bolts - The 351W has six bolts attaching the valve covers; the 351C and 351M have eight.
Timing Chain Cover - The 351W has a timing cover bolted to the engine block, while the 351 C and M both have timing covers built into the big block.
Thermostat - the thermostat on the 351W is a part of the intake manifold, whereas on the 351 C and 351M, it is located on the front cover.
Water Pump Housing - One of the fastest ways to tell is to look at the water pump housing. The 351W has a flat front, while the “C” version has the water pump housing cast into the block.
Deck Height - The 351M has a taller deck height than either the Cleveland or the Windsor, sitting at 10.297 vs. (9.48 pre-1971 and 9.503 on post-’71 on 351W; 9.02 on the 351C).
What Modifications Did the 351 Windsor Undergo?
Over the years of its production, the 351W got tweaked a bit. Before 1971, the deck height was increased from 9.48 to 9.503 to lower compression ratios and nitrogen oxide emissions without changing the cylinder heads. In 1974, the oil dipstick was moved from near the timing case to the left rear, and a boss for an additional intake pump was added to the right front.
For the 1977 models, Ford changed the bolt pattern for the intake manifold from 16 bolts to 12. Since the 351 has larger head bolt threads than the 302, this forced owners to drill out the holes even though the pattern was interchangeable.
In 1983, the rear main seal was changed from a 2-piece configuration to one. Then, ten years later, the engine was redesigned again to accommodate roller lifters instead of the flat-tappet variety that had been a part of the engine for so many years. The motors came to be known as “roller blocks” and are very rare and highly coveted by classic car enthusiasts.
Why Did Ford Stop Making the 351W?
Unfortunately, the small push-rod engines were replaced by the modular overhead cam engines that produced higher rpms more quickly and provided more torque. The 351W was discontinued in the late 70s as an engine for sedans but continued its presence in Econoline vans and F150s. The 5.0 V8 DOHC engine eventually began to replace the small block V8 with engines with fuel injection until the company decided to phase out the engine completely.