Ford small block engine

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Ford small block
289 K-code in a Shelby GT350
Overview
Manufacturer	Ford Motor Company
Also called	Windsor V8 Challenger V8[1]
Production	July 1961 – 2002
Layout
Configuration	Naturally aspirated 90° V8
Displacement	221 cu in (3.6 L) 255 cu in (4.2 L) 260 cu in (4.3 L) 289 cu in (4.7 L) 302 cu in (4.9 L) 351 cu in (5.8 L)
Cylinder bore	4.000" (289, 302, 351W) 3.800" (260) 3.680" (255) 3.500" (221)
Piston stroke	3.500" (351W) 3.000" (302 & 255) 2.870" (221, 260, 289)
Cylinder block material	Cast iron Deck height: 9.480" (1969–70 351W) 9.503" (1971–96 351W) 8.201–8.210" (BOSS 302) 8.206" (221, 260, 289, 302)
Cylinder head material	Cast iron
Valvetrain	Pushrod OHV Cast iron cam, Flat tappet (1962–84 302, 1969–93 351W) Steel roller cam & lifters (1985–2001 302, 1994–97 351W)
Compression ratio	9.0:1, 9.5:1, 10.5:1, 8.8:1, 8:1
Combustion
Fuel system	Carbureted (1962-1985 302, 1969-1991 351W) EFI (1988-1997 351W, 1986-2001 all others)
Fuel type	87 Octane
Oil system	Wet sump
Cooling system	Water-cooled; jacketed block
Output
Power output	115–310 hp (86–231 kW)
Torque output	262–385 lb⋅ft (355–522 N⋅m)
Dimensions
Length	27.50" (302, 351W) [a]
Width	21.00" (351W) 18.75" (302)
Height	23.75" (351W) [b] 20.75" (302)
Chronology
Predecessor	Ford Y-block engine
Successor	Ford Modular engine

The Ford small-block (aka Windsor V8) is a series of 90° overhead valve small-block V8 automobile engines manufactured by the Ford Motor Company from July 1961 to December 2000.

Designed as a successor to the Ford Y-block engine, it was first installed in the 1962 model year Ford Fairlane and Mercury Meteor. Originally produced with a displacement of 221 cu in (3.6 L), it eventually increased to 351 cu in (5.8 L) with a taller deck height, but was most commonly sold (from 1968–2000) with a displacement of 302 cu in (later marketed as 5.0 L).

Famed variants powered 289 Shelby Cobras to Trans-Am racing championships and the Ford GT-40 to wins at LeMans and 1-2-3 sweeps in its iconic 5L form. The Boss 302 also was a Trans-Am design.

The small-block was installed in several of the company's most famous products, notably the Mustang, as well as the Mercury Cougar, Ford Torino, Ford Granada, Mercury Monarch, Ford LTD, Mercury Marquis, Ford Maverick, and Ford F-150 pickup.

For the 1991 model year, Ford began phasing in their new Modular V8 engine to replace the small-block, beginning with the Lincoln Town Car and continuing through the 1990s. The 2001 Explorer SUV was the last North American installation of the engine, and Ford Australia used it through 2002 in the Falcon and Fairlane.

Although sometimes called the "Windsor" by enthusiasts, Ford never used that designation for the engine line as a whole; it was only adopted well into its run to distinguish the 351 cu in (5.8 L) version from the 351 cu in (5.8 L) "Cleveland" version of the 335-family engine that had the same displacement but a significantly different configuration, and only ever used to refer to that specific engine in service materials. The designations for each were derived from the original locations of manufacture: Windsor, Ontario and Cleveland, Ohio.

From 1962 through the 1990s, these engines were marinized by various companies (except for the 255 cu in (4.2 L)).

The small-block remains available for purchase from Ford Performance Parts as a crate engine.^[2]

The small-block engine was introduced in the 1962 Ford Fairlane and Mercury Meteor cars. Displacing 221 cu in (3.6 L), it was designed to save weight, using thin-wall casting for a short-skirt block that does not extend below the centerline of the crankshaft. The engine uses a separate aluminum timing chain cover, which differentiates it from the later 335-series Cleveland engines that use an integrated timing cover. All Ford small-block engines use two-valve-per-cylinder heads, with "2V" and "4V" designations indicating the number of barrels (or venturi) in the carburetor. The valves are in-line and use straight six-bolt valve covers. Coolant is routed out of the block through the intake manifold.

The design was soon bored to 260 cu in (4.3 L) and again to 289 cu in (4.7 L), then stroked to 302 cu in (4.9 L), settling on the most common displacement offered until the engine's retirement in 2001, nearly 40 years after the basic block design debuted. Two additional displacements were produced during the engine's history. A 351 cu in (5.8 L) model was offered beginning in 1969 and continuing until 1996. The 351W (so identified to distinguish from the 335-series Cleveland 351C) uses a taller block than the other engines in the series to avoid excessively short connecting rods. And for a brief time in the early 1980s, a version with a smaller bore diameter that displaced 255 cubic inches (4.2 L) was produced as Ford struggled with emissions and fuel economy.

In response to the Chevrolet Camaro's success in the SCCA Trans-Am Series, Ford engineers developed a new racing engine from the small block. The first attempt mated a tunnel-port head to a 289 cu in block, but the displacement proved to be too small to deliver the desired power. The next iteration of the engine mated an improved head design to the 302 cu in block, producing the famous "Boss 302". The heads from the Boss 302 became the production heads on the 335-series Cleveland engines, which used the same bore spacing and head bolt configuration as the small block engines.

As the 1980s drew to a close, Ford began the design of a new OHC V8 to replace the venerable small block design. The Modular 4.6 L OHC V8 debuted in the 1991 Lincoln Town Car, signaling the eventual demise of the OHV Ford small-block. Through the rest of the decade, Ford gradually shifted V8 applications to the Modular engine, with the Mustang transitioning in 1996. Even as the small-block neared the end of its life, development continued, with new cylinder heads introduced for the Ford Explorer in 1997. American sales in new vehicles ended with the 2001 Ford Explorer, but the engine continues to be offered for sale as a crate engine from Ford Racing and Performance Parts.

All 221, 260, and 289 engines built from July 1961 through August 1964 used a five-bolt bell housing, with all 221s and 260s being of this configuration, but the 289 changed to the six-bolt arrangement at this time – the change was made to resolve transmission utilization issues, such as the need for larger-diameter clutches.

The block mount pads and the cylinder wall contour of the 221 and 260 engines changed in January–February 1963 with the introduction of the 289 variant – all 221 and 260 engine blocks up to this time featured "corrugated wall" construction with two core plugs on the side of each bank and engine mount hole pitch distances of 6 inch.

All three block variants from this point on featured the straight wall method of construction, three core plugs, and an engine mount hole pitch distance of seven inches. The corrugated wall method of block construction had caused cleaning difficulties in the foundry from day one and a change was phased in.

The first engine of this family, called the Fairlane V8,^[1] introduced for the 1962 model year as an option on the Fairlane and Meteor, had a displacement of 221 cu in (3.6 L), from a 3.5 in (89 mm) bore and 2.87 in (72.9 mm) stroke, with wedge combustion chambers for superior breathing. An advanced, compact, thinwall-casting design, it was 24 in wide, 29 in long, and 27.5 in tall (610 mm × 737 mm × 699 mm). It weighed only 470 lb (210 kg) dry despite its cast iron construction, making it the lightest and most compact V8 engine of its type of the era.

In stock form, it used a two-barrel carburetor and a compression ratio of 8.7:1, allowing the use of regular rather than premium gasoline. Valve diameters were 1.59 in (40.4 mm) (intake) and 1.388 in (35.3 mm) (exhaust). Rated power and torque (SAE gross) were 145 hp (108 kW) at 4,400 rpm and 216 lb⋅ft (293 N⋅m) at 2,200 rpm.

The 221 was phased out end of May 1963 as a result of lackluster demand. About 371,000 had been produced.

In the late 1970s, an urgent need to meet EPA CAFE standards led to the creation of the 255 cu in (4.2 L) version for the 1980 model year, essentially a 302 with the cylinder bores reduced to 3.68 in (93.5 mm). The 302 was to be phased out and the 255 was to be an interim engine which would remain until the new V6 was in production. Rated power (SAE net) was 115–122 hp (86–91 kW), depending on year and application. Cylinder heads, which were specific to this engine, used smaller combustion chambers and valves, and the intake ports were oval whereas the others were all rectangular. The only externally visible clue was the use of an open-runner intake manifold with a stamped-steel lifter valley cover attached to its underside, reminiscent of previous-generation V8 engines, such as the Y-block and the MEL.

It was optional in Fox-chassis cars including the Mustang (and corporate cousin Mercury Capri), Thunderbird, and Fairmont, and standard equipment in the Ford LTD. Some variants (such as the one used in the Mercury Grand Marquis) were fitted with a variable-venturi carburetor which were capable of highway fuel economy in excess of 27 mpg_‑US (11 km/L; 32 mpg_‑imp). Due to its dismal overall performance, the 255 was dropped at the end the 1982 model year with 253,000 units manufactured; however, 302 production continued and the plans to phase it out were dropped.

Applications:

• 1980–1981 Ford Fairmont
• 1981–1982 Ford F-100
• 1981–1982 Ford Granada
• 1981–1982 Ford LTD
• 1980–1982 Ford Mustang
• 1980–1982 Ford Thunderbird
• 1980–1982 Mercury Capri
• 1980–1982 Mercury Cougar
• 1981–1982 Mercury Marquis
• 1980–1981 Mercury Zephyr

The second version of the Fairlane V8 was given the name Challenger, and was introduced during the middle of the 1962 model year (March 1962).^[1] It had a larger bore of 3.80 in (96.5 mm), increasing displacement to 260 cu in (4.3 L). Compression ratio was raised fractionally to 8.8:1. The engine was slightly heavier than the 221, at 482 lb (219 kg). Rated power (still SAE gross) rose to 164 hp (122 kW) at 4400 rpm, with a peak torque of 258 lb⋅ft (350 N⋅m) at 2200 rpm.

For the 1962 and 1963 car model years, the valve head diameters remained the same as the 221, but for the 1964 car model year, they were enlarged to 1.67 in (42.4 mm) (intake) and 1.45 in (36.8 mm) (exhaust) – this was a manufacturing economy measure so that both 260 and 289 engines could use the same valves. Although the engine breathed better, and was capable of producing marginally more power, rated power was not changed.

In 1963, the 260 became the base engine on full-sized Ford sedans. Later in the model year, its availability was expanded to the Ford Falcon and Mercury Comet. The early "1964½" Ford Mustang also offered the 260.

Ford ceased production of the 260 at the end of the 1964 car model year with approximately 604,000 units having been made.

The special rally version of the Falcon and Comet and early AC Cobra sports cars of 1962 used a high-performance version of the 260 with higher compression, hotter camshaft timing, upgraded connecting rods, valves with larger diameter valve stems, stronger valve springs and a four-barrel carburetor. This engine was rated (SAE gross) 260 hp (194 kW) at 5800 rpm and 269 lb⋅ft (365 N⋅m) at 4800 rpm. This engine was termed the HP-260 by Ford and was specifically made for Carroll Shelby – about 100 were made.

The 1964–1966 Sunbeam Tiger Mk I used the 260.

The 1967 Sunbeam Tiger Mk II used the 289 ci in V8 when the 'build ahead' stocks of the 260 ran out.

The 289 cu in (4.7 L) was also introduced in April 1963 and was also called the Challenger V8.^[1] Bore was expanded to 4.00 in (101.6 mm), becoming the standard bore for most small block Ford engines. Stroke remained at 2.87 inches. The 289 weighed 506 lb (230 kg).

In 1963, the two-barrel (2V) 289 replaced the 260 as the base V8 for full-sized Fords. It had 8.7:1 compression and was rated at 195 hp (145 kW) (SAE gross) at 4,400 rpm and 285 lb⋅ft (386 N⋅m) at 2,200 rpm.

In 1964, an intermediate performance version of the engine was introduced with a four-barrel carburetor and 9.0:1 compression, rated at 210 hp (157 kW) at 4,400 rpm and 300 lb⋅ft (407 N⋅m) at 2,800 rpm.

The engine was an option on the 1965 Ford Mustang and was known as the "D-code" from the letter code used to identify the engine in the VIN.^[3][4]

The D-code engine is relatively rare, as it was only offered as an optional engine in the latter half of the 1964 model year.

This engine was marketed in the 1964 Mercury Comet Cyclone as the "Cyclone"^[1] and carried a K-code in its Mercury VIN. This engine is not the same engine as the HiPo K-code engine offered in Ford vehicles.

For 1965, the compression ratio of the base 289 was raised to 9.3:1, increasing power to 200 hp (149 kW) at 4,400 rpm and torque to 282 lb⋅ft (382 N⋅m) at 2,400 rpm.

In 1968, the two-barrel was reduced to 195 hp (145 kW).

In 1965, the four-barrel (4V) version was increased to 10.0:1 compression, and was rated at 225 hp (168 kW) at 4,800 rpm and 305 lb⋅ft (414 N⋅m) at 3,200 rpm.

The 289-4V was also the engine for the Australian Ford XR Falcon GT, its first Falcon GT,.

Around 3,500,000 289-2V and 289-4V engines were made at Cleveland Engine Plant 1 (CEP1) and 800,000 289-2V at Windsor Engine Plant 1 (WEP1) in 1963-1967.

A high-performance version of the Challenger 289 engine^[1] was introduced late in the 1963 model year as a special order for Ford Fairlanes. The engine is informally known as the HiPo or the "K-code" (after the engine letter used in the VIN code of cars so equipped). It was the only 289 engine available in the intermediate Fairlanes, with lesser-powered cars receiving the 260 V8. Starting in June 1964, it became an option for the Mustang.

The HiPo engine was engineered to increase performance and high-rpm reliability over the standard 289. It had solid valve lifters with more aggressive cam timing; 10.5:1 compression; a dual point centrifugal advance distributor; smaller combustion chamber heads with cast spring cups and screw-in studs; low-restriction exhaust manifolds; and a bigger, manual-choke 595 CFM carburetor (105 CFM more than the standard 289-4V). The water pump had fewer vanes (to minimize high rpm foaming and cavitation), the fuel pump received an extra spring to keep up with high rpm demand, alternator/generator pulleys were larger diameter, respectively (to slow their relative speeds at high engine revs), and a special fan was fitted.

Bottom-end high-rpm improvements included a flaw-free selected standard block, thicker main bearing caps and crankshaft damper/balancer, larger-diameter rod bolts, a crankshaft made from 80% nodular iron as opposed to the regular item's 40% (with each one checked for correct 'nodularity' by polishing an area of the rear counterweight and comparing a magnification of that surface against a standard), and increased crankshaft counterweighting to compensate for the heavier connecting rod big ends. (The external counter weighting at the front was split between the crankshaft damper and a supplementary counterweight place adjacent to the front main bearing journal, all designed to reduce the 'bending moment' in the crankshaft at high-rpm.)

The HiPo equipped with a single 4-barrel Autolite 4100 carburetor carried SAE gross ratings of 271 bhp (275 PS; 202 kW) at 6,000 rpm and 312 lb⋅ft (423 N⋅m) at 3,400 rpm.^[5]

The K-code HiPo engine was an expensive option and its popularity was greatly diminished after the 390 and 428 big-block engines became available in the Mustang and Fairlane lines, which offered similar power (at the expense of greater weight, and worsened front/rear weight distribution) with cheaper parts at far less cost.

The HiPo engine was used in modified form by Carroll Shelby for the 1965–1967 Shelby GT350, receiving special exhaust headers, an aluminum intake manifold, and a larger 4-barrel Holley 715 CFM carburetor, which rated power to 306 bhp (310 PS; 228 kW) at 6,000 rpm and 329 lb⋅ft (446 N⋅m) at 4,200 rpm of torque.^[6][7] Shelby also replaced the internal front press-in oil gallery plugs with threaded plugs to reduce chances of high rpm failure, and installed a larger oil pan with baffles to reduce oil starvation in hard cornering.

From 1966 to 1968, Shelby offered an optional Paxton supercharger on Shelby GT350 289s, raising power to around 390 hp (291 kW).^{[citation needed]}

About 25,000 K-code 289s were manufactured at Cleveland Engine Plant 1 (CEP1) between March 1963 and June 1967.

By 1967, the Ford GT40 MKII and GT40 MKIV had dominated the Le Mans 24-Hour Race for two consecutive years, using various versions of the Ford big-block engine. In an attempt to reduce the high speeds, the organizers of this race capped the engine capacity in 1968. Ford consequently returned to the MKI GT40 (originally using the Windsor 289), but had now increased its capacity to meet the new rules. Since Ford had ruled that the GT40 engines must have a direct link back to its production cars,^[clarify] the 302 was adopted in domestic manufacturing.^{[citation needed]} Both two-bolt and four-bolt main bearing versions were made.

In 1968, the small-block Ford stroke was increased from 2.87 in (72.9 mm) to 3 in (76.2 mm), giving a total displacement of 4,942 cc (4.9 L; 301.6 cu in). The connecting rods were shortened to allow the use of the same pistons as the 289. The new 302 replaced the 289 early in the 1968 model year.

The most common form of this engine used a two-barrel carburetor, initially with 9.5:1 compression. It had hydraulic lifters and valves of 1.773 in (45.0 mm) (intake) and 1.442 in (36.6 mm) (exhaust), and was rated (SAE gross) at 220 hp (164 kW) at 4,600 rpm and 300 lb⋅ft (407 N⋅m) at 2,600 rpm. Optional was a four-barrel version rated at 230 hp (172 kW) at 4,800 rpm.

The 302/5.0 was primarily manufactured at Ford's Cleveland engine plant in Brook Park, Ohio, just as its predecessors were, though Windsor Engine No. 2 manufactured truck-spec 5.0s from 1982 to 1996.^[8] The 302 received several changes over the course of its production run. These were longer valve stems with rotating lash caps, bottle neck type rocker studs for a positive stop nut arrangement and a longer pushrod to correct valve train geometry. The water pump borrowed from the 351 Cleveland, with a few minor alterations to the casting, allowed the use of a left hand water inlet. (this improved water circulation in the radiator to a more cross-flow direction). This change also necessitated the need for a harmonic damper change to move the timing marks to the other side of the front timing cover and a change to four bolts holding the crank pulley rather than just three.

Emission regulations caused a progressive reduction in compression ratio for the 302 two-barrel, to 9.0:1 in 1972, reducing SAE gross horsepower to 210 hp (157 kW). In that year, U.S. automakers began to quote horsepower in SAE net ratings; the 302 two-barrel carried a net rating of 140 hp (104 kW). By 1975, its power had dropped as low as 122 hp (91 kW) in some models. Until fuel injection began to appear in the 1980s, net power ratings did not rise above 210 hp (157 kW).

From the 1978 model year, the 302 became more commonly known as the 5.0 Liter, although its metric displacement is 4,942 cc (4.9 L; 301.6 cu in). Despite Ford's usage, Car and Driver referred to the 302 as a 4.9-liter engine.^[when?] Other terms for it included "5-Oh", "5-Point-Oh", and "5 Liter".

Throttle-body fuel injection became available on the 1980 Lincoln Continental, and became standard on all non-H.O. 5.0 engines for 1983. For the 1986 model year, Ford replaced the throttle-body system with sequential multi-port fuel injection, identifiable by the large intake with an "EFI 5.0" badge on top.

Variants of the engine remained in use in Ford passenger cars and light trucks through the mid-1990s, and in SUVs until 2001.

For 1968 only, a special high-performance Shelby-modified version of the 302 was offered by Ford in the Shelby GT350.^[9] The main features included: an angled, high-rise aluminum or iron intake manifold, a larger Holley four-barrel carburetor, and bigger valves of 1.78 in (45 mm) intake and 1.6 in (41 mm) exhaust. It had a longer-duration camshaft, still with hydraulic lifters. The heads had special close-tolerance pushrod holes to guide the pushrods without rail rocker arms or stamped steel guide plates. The combustion chambers also featured a smaller quench design for a higher compression ratio and enhanced flow characteristics. Additionally, high-flow cast exhaust manifolds similar to those on the 289 Hi-Po K-code engine further improved output. Heavy-duty connecting rods with high-strength bolts and a nodular iron crankshaft were also included in this package. Rated power (SAE gross) was estimated at 315 hp (235 kW) at 6,000 rpm and 333 lb⋅ft (451 N⋅m) at 3,800 rpm.

The package, which cost $692 including some other equipment, was not popular and did not return for 1969. This engine is well documented in the Ford factory engine repair manual for 1968 Mustangs and Fairlanes.^{[citation needed]}

The 1982 model year brought a new 5.0 High Output variation of the 302. Manual-transmission equipped Mustangs and Mercury Capris were first equipped with two-barrel carburetors (1982), then a four-barrel Holley carburetor (1983–85). The block was fitted with revised, taller lifter bosses to accept roller lifters, and a steel camshaft in 1985, and electronic sequential fuel injection was introduced in 1986. While sequential injection was used on the Mustang beginning in 1986, many other vehicles, including trucks, continued to use a batch-fire fuel injection system. The speed-density based ECU-controlled electronic fuel-injection (EFI) systems used a large, two-piece, cast-aluminum manifold. It was fitted on all 302 engines through 1988, after which year it was phased out for a mass airflow sensor (MAF) system in most applications (non–California compliant Panther platform cars retained the speed-density system until the Lincoln Town Car received the 4.6 L OHC Modular V8 for model year 1991, and the Crown Victoria and Grand Marquis for 1992).

The same manifold was used in MAF applications, with the addition of the MAF sensor in the air intake tube. The MAF system continued, with minor revisions, until the retirement of the engine in 2001. Ford offered a performance head that was a stock part on 1993–1995 Mustang Cobra models and pre-1997 ½ Ford Explorers and Mercury Mountaineers equipped with the 5.0 L engine called the GT-40 head (casting ID F3ZE-AA). In mid-1997, the Explorer and Mountaineer 5.0 L heads were revised and renamed GT40P. The GT40P heads, unlike the GT40 heads, had a very well-developed port shape/design which yielded about 200 cfm on the intake side and 140 cfm on the exhaust side without increasing the size of the ports at all from standard E7TE castings, and without increasing the exhaust valve size. These highly-efficient heads also had smaller 59–61 cc combustion chambers for added compression, and the combustion chamber shape was revised to put the spark plug tip near the center of the chamber for a more even burn.

The 302 is still available as a complete crate motor from Ford Racing Performance Parts.^{[when?][citation needed]}

Applications:

• 1982–1995 Ford Mustang
• 1982–1986 Mercury Capri
• 1984–1985 Ford LTD LX
• 1984–1985 Ford Sierra XR8 (South Africa)^[10]
• 1985 Mercury Marquis LTS
• 1987–1992 Lincoln Mark VII (1987 LSC models only)
• 1991–1993 Ford Thunderbird
• 1991–1993 Mercury Cougar
• 1991–2002 Ford Falcon
• 1991–2002 Ford Fairlane/Ford LTD
• 1996–2001 Ford Explorer
• 1997–2001 Mercury Mountaineer
• 1990–1996 Panoz Roadster

The 302 was marinized and offered in both standard and reverse-rotation setups.

In 2001, Ford Australia also built some stroked, 5.6 L (5,605 cc, 342 cu in) small blocks with reworked GT40P heads (featuring larger valves), a unique eight-trumpet inlet manifold fitted with a unique throttle body, long-throw crank, H-beam rods, and roller rockers. Used in vehicles known as “T” series Ford Falcons and XR8 Pursuit 250 in their last collaboration (and possibly the last production use of the small block) in 2001–2002. Vehicles fitted with these stroker engines were sold under the banner of, and only available from dealers under the FTE banner (Ford Tickford Experience). They were produced in conjunction with long standing performance partner Tickford. They produced 335 hp (250 kW) at 5,250 rpm and 369 lb⋅ft (500 N⋅m) at 4,250 rpm.^[11] The 5.6 litres of displacement were reached by lengthening the stroke from 76.2 mm (3.0 in) to 86.4 mm (3.4 in).^[12]

In response to a new LeMans regulation which limited engine displacement to 5 L (305 cu in), Ford added an extra 1/8-inch of piston travel to the 289 Hi-Performance V8, yielding the 302 cu in (4,949 cc) block. It featured heavy-duty four-bolt main bearing caps and pressed in core plugs, and was topped with Gurney-Weslake aluminum heads. About 50 blocks were made.^{[citation needed]}

Ford's new 302 "Tunnel-Port" engine was originally envisioned as the secret weapon for the 1968 Trans-Am racing season, which would bring them a third Championship win.

Starting with a 1967 GT-40 block, Ford topped the engine with a new head design. The new heads were based on the design of Ford's NASCAR 427 heads. The intake ports were straight, instead of snaking around the push rods. The push rods actually went through the center of the ports (thus the name "Tunnel-Port"). This configuration also enabled larger valves to be used.

The 302 tunnel-port motor was topped off with an aluminum dual quad intake.

Shelby dyno sheets showed this engine was capable of producing horsepower in the 440 to 450 range, and operated through a very high rpm band (8000+).

Originally the "302 H.O.", the Boss 302 was a performance variant of the small block designed to allow Ford to wrest back the 5 L (305 cu in) Trans-Am racing championship from the Camaro Z/28. Inspired by chief engineer Bill Gay and realized by Bill Barr, it put large-port, large-valve, quench-chambered, free-flowing "Cleveland"-type cylinder heads^[13] (adapted from the design destined for the 351 Cleveland to debut later in 1969) on a special racing block to improve rated power to 290 hp (216 kW). According to some reports, the canted-valve, deep-breathing, high-revving engine could produce more than 310 hp (231 kW), although it was equipped with an electrical revolution limiter that restricted maximum engine speed to 6,150 rpm. The 302 H.O. borrowed some components (and approach) from the 289 HiPo. A strong 4-bolt main bottom end, thicker cylinder walls, steel screw-in core plugs, aggressive forged-steel crank, special HD connecting rods, and Cleveland-style forged pistons were geared to racing. The Boss 302 Mustang was offered only for the 1969 and 1970 model years. In the January 2010 issue of Hot Rod magazine, a Boss 302 engine built to the exact specifications, settings, and conditions of the original engine was tested. It produced 372 hp at 6,800 rpm and 325 lb-ft of torque at 4,200 rpm.

The 351W (Windsor) made its debut in 1969; it is often confused with the Ford 351 Cleveland, a different engine of near identical displacement that also began production in 1969. The 351.9 cu in (5.8 L; 5,766 cc) Windsor featured a 1.3 in (32.5 mm) taller deck height than the 289/302, allowing a stroke of 3.5 in (88.9 mm). It was initially rated (SAE gross) at 250 hp (186 kW) with a two-barrel carburetor (referred to as "2V" in engine designations) or 290 hp (216 kW) with a four-barrel (designated "4V"). Emissions compliance led to a compression drop in 1971, and when Ford switched to net power ratings in 1972 power ratings had fallen to 153 to 161 hp (114 to 120 kW).

Although very much related in general configuration to the 289/302, in that the three engines share the same bellhousing, motor mounts, and other small parts, the 351W had larger main bearing caps, thicker and 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, a means to move the unacceptable "noise" of the consecutively-firing adjacent front cylinders to the sturdier rear part of the engine block all while reducing excessive main bearing load), 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.

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 the 302, 1/2 inch for the 351W). Early blocks (casting ID C9OE-6015-B) had enough metal on bearing saddles 2, 3, and 4 for four-bolt mains, and as with all small-block Fords (SBFs), 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 reintroduced for use in light trucks and vans. In 1988, fuel injection replaced the four-barrel carburetor. Roller camshaft/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. A number of fatigue failures were attributed to the machining of the part, 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 were machined in metric and SAE units, respectively. The cap featured a longer boss for balancing than the original design.

In 1971 block deck height was extended from 9.480 to 9.503 in (240.8 to 241.4 mm) (casting D1AE-6015-DA) to lower the compression ratio to reduce NO_x 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 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. In 1984, the rear main seal was changed from a two-piece to a single-piece design.

Around 8.6 million 351W engines were manufactured between 1969 and 1996 at the Windsor Engine Plant Number One.

Applications:

• 1969–1974 Ford Galaxie
• 1969–1970 Ford Mustang
• 1969–1971 Mercury Cougar
• 1969–1991 Ford Country Squire
• 1969–1970 Ford Fairlane (Americas)
• 1970–1976 Ford Torino
• 1974–1976 Ford Elite
• 1975–1996 Ford E series
• 1977–1979 Ford LTD II
• 1977–1979 Ford Thunderbird
• 1979–1996 Ford Bronco
• 1979–1982 Ford LTD (Americas)
• 1979–1991 Ford LTD Crown Victoria (after 1982, this engine would only be sold for police sales in the U.S.)
• 1983–1997 Ford F-Series
• 1977–1979 Mercury Cougar (station wagons only)
• 1978, 1986–1991 Mercury Colony Park
• 1978–1982 Mercury Marquis
• 1986–1991 Mercury Grand Marquis
• 1980 Continental Mark VI
• 1995 Ford Mustang SVT Cobra R

From the late 1960s through the early to mid-1990s, the 351 Windsor had a long history of being marinized by Holman Moody Marine, Redline of Lewiston, ID (now defunct), Pleasure Craft Marine (PCM), and Indmar for use in about every make of recreational boat, including; Correct Craft, Ski Supreme, Hydrodyne, MasterCraft, and Supra inboard competition ski boats. The early marinized engines were rated at 220 hp (164 kW). Most PCM and Indmar marinized 351s were rated at 240 hp (179 kW). In the early 1990s, a 260 hp (194 kW) version and a high-output version that used GT-40 heads and the Holley 4160 marine carburetor was rated at 285 hp (213 kW). A few 351 GT-40/HO engines were marinized equipped with throttle-body fuel injection (TBI) and were rated at 310 hp (231 kW). The marine industry's relationship with the 351W platform ended when Ford was unable or unwilling to compete with GM's production of TBI- and MPI-equipped engines in mass quantity. During that time, the recreational marine community's small-block V8 platform of choice shifted to the 350 cu in (5.7 L) Chevrolet L31 (Vortec 5700) engine series.

In the 2000s, Ford Racing Performance Parts sold two "Boss" crate engines and at least one 351 block. Most Ford racing versions of the 302 and 351 feature a siamesed bore and many of them feature drilled coolant crossover holes.^{[14][15][16][17][18][19]}

The new Boss 302 engine was unveiled in the 2006 SEMA show.^[20]

The "Racing Boss 351" (not to be confused with the Ford 335 engine Cleveland-based Boss 351) is a crate engine based on the 351 cu in (5,752 cc) Ford Windsor engine, but uses Cleveland sized 2.75 in (70 mm) main bearing journals. Deck height choices include 9.2 in (234 mm) and 9.5 in (241 mm). Maximum displacements are 4.25 in (108 mm) stroke and 4.125 in (105 mm) bore. The resulting maximum displacement is 454.38 cu in (7,446 cc).

The uncross-drilled block with increased bore capacity became available from the third quarter of 2009. A 427 cu in (6,997 cc) Boss 351-based crate engine producing 535 hp (399 kW) was available from the first quarter of 2010.

In 2010, the MSRP for the Boss 351 block was US$1,999.^[21]

• List of Ford engines

• Martin, Isaac (1999). Ford Windsor Small-Block Performance: Parts and Modifications for High Performance Street and Racing (1st ed.). Penguin Group, Inc. pp. 1–2. ISBN 1-55788-323-8.
• Nötzli, Max, ed. (7 March 2002). Automobil Revue 2002 (in German and French). Vol. 97. Berne, Switzerland: Büchler Grafino AG. p. 288. ISBN 3-905-386-02-X.
• Reid, George (2001). How to Build Max Performance Ford V-8S on a Budget. Cartech, Inc. pp. 5–6. ISBN 1-884089-55-0.

• Short descriptions of Ford overhead valve V8 engines