Ford Windsor Engine - 351W

351W

The 351W is often confused with the 351 Cleveland, which is a different engine of identical displacement

The 351 cu in (5.8 L) Windsor featured a 1.3 in (32.5 mm) taller deck height than the 302, allowing a stroke of 3.5 in (88.9 mm). Although related in general configuration to the 289-302 and sharing the same bell housing, motor mounts and other small parts, the 351W had a unique, tall deck block, larger main bearing caps, thicker, longer connecting rods, and a distinct firing order (1-3-7-2-6-5-4-8 versus the usual 1-5-4-2-6-3-7-8), adding some 25 lb (11 kg) to the engine's dry weight. The distributor is slightly different to accommodate a larger oil pump shaft and larger oil pump. Some years had threaded dipstick tubes. It had a unique head which optimized torque over high-rpm breathing, frequently replaced by enthusiasts with aftermarket heads providing better performance. The early 1969 and 1970 heads had larger valves and ports for better performance. The intake valves and ports were slightly larger on the early engines. The head castings and valve head sizes from 1969 to 1976 were different, notably in passages for air injection and spark plug diameters (1969-1974 18 mm, 1975 and up 14 mm). From 1977 onward, the 351W shared the same head casting as the 302, differing only in bolt hole diameters (7/16 inch for 302, 1/2 inch for 351W). Early blocks (casting id C9OE-6015-B had enough metal on bearing saddles 2,3 and 4 for four bolt mains) as with all SBF, were superior in strength to most late model, lightweight castings. Generally the 1969 to 1974 blocks are considered to be far superior in strength than the later blocks making these early units some of the strongest and most desirable in the entire SBF engine family including the 335 series. During the 1980s a four barrel version (intake manifold casting id E6TE-9425-B) was re-introduced for use in light trucks and vans. In 1988 fuel-injection replaced the four barrel carburetor. Roller lifters were introduced in this engine in 1994.

The original connecting rod beam (forging id C9OE-A) featured drilled oil squirt bosses to lubricate the piston pin and cylinder bore and rectangular head rod bolts mounted on broached shoulders. There were a number of fatigue failures attributed to the machining of the part and so the bolt head area was spot-faced to retain metal in the critical area, requiring the use of 'football head' bolts. In 1975, The beam forging (D6OE-AA) was updated with more metal in the bolt head area. The oil squirt bosses were drilled for use in export engines, where the quality of accessible lubricants was questionable. The rod cap forging remained the same on both units (part id C9OE-A). In 1982, the design of the Essex V6 engine used a new version of the 351W connecting rod (E2AE-A), the difference between the two parts was that the V6 and V8 units was machined in metric and SAE units respectively. The cap featured a longer boss for balancing than the original design.

The block underwent some changes since its inception. In 1971, The deck height was extended from 9.480 in. to 9.503 in. (casting id D1AE-6015-DA) to lower the compression ratio to reduce NOx emissions without the need to change piston or cylinder head design. In 1974 a boss was added on the front of the right cylinder bank to mount the air injection pump (casting id D4AE-A). In 1974 the oil dipstick tube moved from the timing case to the skirt under the left cylinder bank near the rear of the casting. These details made swapping older blocks from passenger cars with front sump oil pans to more recent rear-sumped Mustang and LTD/Crown Vic Ford cars more difficult unless an oil pan had the dipstick mounted therein. In the 1990s the rear main seal was changed from a two-piece component to a one-piece design and provisions for roller tappets were also added.

Introduced in 1969, it was initially rated (SAE gross) at 250 hp (186 kW) with a two-barrel carburetor or 290 hp (216 kW) with a four-barrel. When Ford switched to net power ratings in 1972 it was rated at 153 to 161 hp (114 to 120 kW), although actual, installed horsepower was only fractionally lower than in 1971.

During the 1990s, motor enthusiasts were modifying 351 Cleveland 2V cylinder heads (by re-routing coolant exit from the block surfaces to the intake manifold surfaces) for use in the 351W resulting in the Clevor (combining Cleveland and Windsor). This modification requires the use of custom pistons by reason of differing combustion chamber terrain (canted valves vs. straight valves) and intake manifolds for the Boss 302 was not wide enough and the intake ports were too large. This combination yielded the horsepower potential of the 351C with the ruggedness of the 351W small block. This was possible because more 351C 2V cylinder heads were made than corresponding engine blocks (the 351M and 400 used the same head as the 351C 2V).