Ford 335 engine
|Ford 335 V8|
|Manufacturer||Ford Motor Company|
|Also called||Ford Cleveland V8|
|Configuration||Small-block OHV V8|
|Displacement||302 cu in (5 L)
351 cu in (5.8 L)
400 cu in (6.6 L)
|Cylinder bore||4.0 in (102 mm)|
|Piston stroke||3.0 in (76 mm)
3.5 in (89 mm)
4.0 in (102 mm)
|Cylinder block alloy||Iron|
|Cylinder head alloy||Iron|
|Successor||Ford Windsor V8|
The Ford 335 engine family were a group of small-block V8 engines built by the Ford Motor Company between 1970 and 1982. The significance of the Numerals '335' designated to this series of small-block Ford V8 engines is not known.
The series was nicknamed Cleveland after the Cleveland, Ohio engine plant in which most of these engines were manufactured, a plant complex in Brookpark, Ohio that included a gray iron foundry (casting plant), a stamping plant, and an engine assembly plant. As newer automobile engines began incorporating aluminum bodies, Ford eventually also developed that approach, and closed the casting plant in May 2012. The 335 was used as an option in mid-sized vehicles and trucks concurrently with the larger 351 member of the Windsor small-block family as well as the mid-sized FE V8 family. Although all three of these engine families continued in production, the Cleveland, only outliving the FE by a half-decade, was eventually abandoned in favor of the more compact Windsor design.
- 1 Overview
- 2 351 Cleveland
- 3 302 / 351 Cleveland (Australia)
- 4 400
- 5 351 M
- 6 Light truck usage
- 7 Replacement in cars
- 8 Replacement in trucks
- 9 351C/400/351M naming convention confusion
- 10 See also
- 11 External links
The 335 series, although sharing the same bore spacing and cylinder head bolt pattern, was very different internally from the somewhat similar-looking Windsor series. The 335 Cleveland used smaller 14mm spark plugs in one of two different cylinder heads, both with 2 valves per cylinder. The '4V' heads had larger ports and valves than the '2V'. Both had the valves canted to the sides in a "poly-angle". The '2V' head had an open, almost hemispherical-shaped combustion chamber while the '4V' sported a quench-type combustion chamber. The Cleveland has a square-shaped rocker cover while the Windsor has a more rounded cover. All 335 covers are secured with 8 bolts; the Windsor uses 6 bolts.
The radiator hose locations differ between the Windsor and Cleveland engines; the Windsor routed coolant through the intake manifold, with the hose protruding horizontally, while the Cleveland had a dry manifold with the radiator hose connecting vertically to the cylinder block above the cam timing chain cover.
The 335 uses large main-bearing caps, allowing 4-bolt attachment on some engines. The oiling sequence does not route the oil supply to the main bearings first, and some critics fault this. However, for all but the highest level of performance applications, it has not proven any less reliable than the Windsor line.
|R||351C-4V "Boss 351"||1971||High||Rare, solid lifters|
|R||351C-4V HO||1972||Low||Very rare, solid lifters, open chamber|
|Q||351C-4V "Cobra-Jet"||May 1971-1974||Low||open chamber|
- See also the Cleveland-derived Boss 351 and quite different 351 "Windsor"
The 351 Cleveland was introduced in 1969 for the 1970 model year as Ford's new performance-car engine and was built through the end of the 1974 model year. It incorporated elements learned on the 385 big-block series and the Boss 302, particularly the poly-angle combustion chambers with canted valves, and thin-wall casting technology. Displacement is actually 351.9 cubic inches (5,766 cc).
A 4V (4-barrel carburetor) performance version and a 2V (2-barrel carburetor) basic version were built, both with 2 valves per cylinder. The latter had a different cylinder head with smaller valves, smaller ports, and open combustion chambers to suit its intended applications.
Only the Q-code 351 "Cobra Jet" (1971–1974), R-code "Boss" 351 (1971), and R-code 351 "HO" (1972) versions have 4-bolt mains although all 335 series engines (351C/351M/400) have provision for them. The main differences between 351C/351M/400 engines are the connecting rod length, and the main bearing size. The 351M/400 engines have the larger bearing size and the taller deck height while sharing the 429/460 bell housing pattern. The 351C engine has a medium main bearing size (2.75") and shorter connecting rods (5.78") than the 351W (5.94") and the 351M/400 (6.58") while retaining the SBF (289-302w) engine mount locations and bell housing pattern. The 400 engine has the longest stroke (4.00") of any SBF or 335 series engine.
All of the 351C and 351M/400 engines differ from the 302/351W by having an integrated timing cover casting in the front of the block to which the radiator hose connects.
The majority of 351 Cleveland engines are H-code 2V (2-venturi carburetor) versions with lower compression. They were produced from 1970 through 1974 and were used on a variety of Ford models, from ponycar to fullsize.
The 351C 4V engines produced in 1970 and 1971 used this code. Engines varied in compression ratio; 1970 engines were 11.0:1 compression and produced 300 bhp (224 kW; 304 PS) at 5400 rpm, while 1971 versions had a slightly lower compression ratio of 10.7:1, and a reduced power output of 285 bhp (213 kW; 289 PS) at 5400 rpm. Ford recommended the use of high-octane gasoline (100+ octane in 1970) which was at the high end of the leaded gasoline available at the time. However, with the mid-1970s introduction of unleaded gasoline and lower octane ratings, and subsequent disappearance of the high-octane fuels required to power these high-compression engines, motorists were either unaware of potential damage or simply unable to find this kind of fuel any more. As a consequence, many of these otherwise durable engines met with an early demise due to the destructive effects of severe engine knocking caused by using low-octane fuel.
1971 R-code (Boss 351)
The Boss 351 is a high-performance variant available only in the 1971 Boss 351 Mustang. Rated at around 330hp (246kW), it was fitted with a four-barrel Autolite spreadbore carburetor, an aluminum intake manifold, and aluminum valve covers. It had four-bolt main block/caps and a premium crankshaft, constructed from high-strength nodular iron. The cylinder head was modified for better airflow and solid lifters were used. The forged connecting rods were shot-peened and magnafluxed for strength, and used stronger bolts/nuts. Forged domed pistons gave an 11.3:1 nominal (11.1:1 advertised) compression ratio. Ford manufactured 1,806 Boss 351 Mustangs in 1971, 591 of which are registered and accounted for on the Boss 351 Registry site.
The January 2010 issue of Hot Rod Magazine reported a project in which a Boss 351 was assembled to the exact internal specifications of an original motor, but fitted with open, long tube, 1-3/4" Hooker headers (vs. the stock cast iron manifolds), a facility water pump, a 750 Holley Street HP-series carburetor (vs. the stock 715 CFM Autolite unit), and minus the factory air filter assembly, engine accessories, or factory exhaust system. In that mildly modified state, it produced 383 hp (286 kW) Gross HP at 6,100 rpm, and 391 lb·ft (530 N·m) torque (gross) at 4,000 rpm. Actual "as installed" output (SAE Net HP) - with all engine accessories, air cleaner assembly, and complete factory exhaust in place, would naturally be expected to be lower.
The R-code 351 Cleveland HO for 1972 was considerably different. The timing was changed, the compression ratio was decreased in order to meet the new emissions regulations, and open-chamber heads were incorporated. It used solid valve lifters. It retained the four-barrel carburetor. This engine produced 275hp (205kW) using the new SAE net system.
The Q-code "351 Cobra Jet" version was produced from May 1971 through the 1974 model year. It was a lower-compression design that included open-chamber "4V" heads, a different intake manifold, hi-lift long-duration camshaft with hydraulic valve lifters, different valve springs and dampers, a 750 CFM 4300-D Motorcraft carburetor, dual-point distributor with 4 speed transmissions only, and 4-bolt main bearing caps. It was rated at 280 bhp (209 kW; 284 PS) for all 1971 applications; 266 hp (198 kW) (SAE net) for 1972 when installed in the Mustang, and 248 hp (185 kW) in the Ford Torino and Mercury Montego. The horsepower rating dropped in 1973 to 246 hp (183 kW) for the 4-barrel for the intermediate Fords, and still retained the higher 266 hp (198 kW) rating in the Mustang. The 351 CJ (now referred to as the "351 4V") was rated at 255 hp (190 kW) in 1974 and was only installed in the Ford Ranchero, Ford Torino, Mercury Montego and the Mercury Cougar.
302 / 351 Cleveland (Australia)
- Note that there was also a 302 "Windsor"
The 302 cu in (4.9 L) Cleveland engine was built only in Australia, from 1972 to 1982, and was intended to give consumers a smaller alternative to the - also locally manufactured - 351 cu in (5.8 L) Cleveland engine; Ford Australia had inherited the patterns, molds and tooling for the 'Cleveland' and it was therefore a viable alternative to importing the 302 Windsor. Using a locally reproduced 351 Cleveland block, 302 cubic inches were attained by reducing the stroke of the 351C from 3.5 to 3.0 in (89 to 76 mm) and increasing the connecting rod length from 5.780 to 6.030 in (146.812 to 153.162 mm). Additionally, the 302C cylinder heads were redesigned locally, with smaller combustion chambers (from 72cc to 58cc), to compensate for the reduced stroke.
The combination of closed combustion chambered quench heads with smaller two-barrel style ports made a more powerful setup known in the USA as "Australian Cleveland heads". These heads interchange directly onto 351C engines, and are somewhat sought after outside of Australia as a low-cost method to increase compression ratio. They are a good street alternative to the over-ported four-barrel heads. Using the 302C cylinder heads on an otherwise unmodified 351C may increase the compression ratio beyond a safe level when regular-octane gasoline is used. Using the small-chamber 302C cylinder heads properly requires engine design checks (deck clearance, piston design, camshaft specifications), all optimized for the intended use.
Manufacture of the 302C and 351C ceased at Geelong in August 1982. The last V8-powered Australian Ford Falcon passenger car to receive a 302C was a silver Ford XE Fairmont Ghia ESP sedan, Vehicle Identification Number JG32AR33633K, in November 1982. Ford Australia continued to make remnant stock of the 351C available in Bronco and F-series vehicles until August 1985. Australian-built 351 engines were also used by De Tomaso in Italy for the Pantera, Longchamp, and Deauville cars after American supplies had come to an end. These engines were tuned in Switzerland and were available with a range of outputs up to 360 PS (265 kW; 355 hp).
The mid block FE engine family was getting outdated, and the big-block 385 family could not meet the efficiency requirements of the time. At the same time, the small-block Windsor engines were too small and high-revving for Ford's fullsize car and truck applications. So the company developed a new small-block to meet the desired levels of economy while still providing the kind of big-block torque that was needed to move 2+ ton vehicles.
The Ford 400 engine was based on the 351 Cleveland but was produced with a taller deck height of 10.297 inches compared to the 351C's 9.206 inches. This allowed for a longer stroke while retaining the 351C's rod-stroke ratio. These blocks also share the same oiling route in the block. The 400 featured larger (Windsor sized 3.00 inch with Cleveland cap register) main-bearing journals and had "square" proportions, with a 4.0 in (102 mm) bore and stroke; it therefore displaced 402 cu in (6.6 L), making it the largest displacement small-block V8 made at that time. It was introduced in model year 1971 with a half-inch (12.7 mm) longer stroke than the 351 Cleveland, making it the longest-stroke Ford pushrod V8 engine. A long-stroke engine has good low-end torque. This was a good compromise given Ford's requirement for an engine to power heavier mid-size and full-size cars and light trucks.
The 400 was seen as a smaller and lighter replacement for the big Ford 385 engines, the 429 and 460, in Ford's larger cars. Weighing just 80% of a similar big-block, it was originally available in Ford's Custom, Galaxie and LTD lines, and in Mercury Monterey, Marquis, and Brougham. Later, it would power the Ford Thunderbird, the Lincoln Continental, Mark V, mid-size Fords and Mercurys, and Ford light-duty trucks.
Most 400 blocks used the same bellhousing bolt pattern as the 385 family big-block to make it compatible with the higher torque-capacity C6 transmission used on the large cars and trucks. There were a small number of 400 block castings produced in 1973 with dual bellhousing patterns for both C6 and FMX transmissions (though not necessarily drilled for both), and provisions for both 351C-style and 400/351M engine mounts. These particular blocks have been dubbed the "400 FMX" by enthusiasts, though were never officially referenced as such by Ford.
The 400 was retuned by Ford in 1975 to use unleaded gasoline.
|Nominal main bearing size||3.000 in (76.2 mm)||2.750 in (69.8 mm)|
|Rod length||6.58 in (167.1 mm)||5.78 in (146.8 mm)|
|Deck height||10.297 in (261.5 mm)||9.206 in (233.8 mm)|
When the 351 Cleveland was discontinued after the 1974 model year, Ford needed another engine in that size range, since production of the 351 Windsor was not sufficient and the 390 FE was also being retired. To replace the 390, Ford took the 400 engine's tall-deck block and de-stroked it with the shorter-throw crankshaft from the 351 Windsor, and taller pistons, to produce a 351 cubic inch (5.8 L) engine whose components were largely compatible with the 400. 351M block castings were modified to prevent cracks in the lifter area; additionally, the 351M casting contains X marks cast next to each lifter bore.
351M production began in 1975 in the Michigan Casting Center, and continued until mid-year 1978, when manufacture was transferred to the Cleveland Foundry/Cleveland Casting Plant.
The M-block, as it became known, was the last pushrod V8 block designed by Ford. The M-block also shares some elements with the Windsor engine family: bore spacing, cylinder head bolt-patterns and crankshaft journal dimensions.
Light truck usage
For the 1977 model year, Ford replaced its FE big-block 360 and 390 engines in its light truck line with its new 351M and 400 engines. For light-truck use, stronger blocks were designed. These enhancements were added to all M-block engines starting with the 1978 model year.
Replacement in cars
The final year the M-block engines were used in cars was 1982. After that, the Ford 351 Windsor at 5.8 L was the only large car engine used. Reduced demand for large engines due to fuel economy regulations led to the abandonment of the Cleveland production line, that produced the 351M and 400 engines, after 1982.
Replacement in trucks
The M-block engine was designed when first-generation pollution controls were already in place. Most Ford V8s required bulky and unsightly external tubing to feed Thermactor air into the exhaust manifolds and exhaust gas to the EGR valve below the carburetor, but this was all built into the M-block engine. This made adapting the M-block to the second generation of emissions control equipment harder. One requirement of the second-generation equipment was an oxygen (O2) sensor in the exhaust, which had to be placed before the Thermactor air was added. Since Thermactor air was injected right into the block's exhaust ports in the M-block, there was nowhere for the O2 sensor to go.
It would have been possible to alter the M-block to work, but it would have required significant effort and cost. Ford decided to simply scrap the M-block engines and replace them with updated 351 Windsor engines at the small end, and a combination of the 6.9 L Navistar International diesel and the 460 at the top end. Sales of the M-block ended in 1982.
351C/400/351M naming convention confusion
There exists debate as to what Ford intended the "M" designation of the 351M to refer to. Some claim the "M" stands for “Modified” - due to the derived components from both the "Cleveland" (block, heads) and "Windsor" (crankshaft) components - though others claim that the "M" refers to the Michigan Casting Center, where the 351M began production.
Likewise, Ford's use of the 400 block in the creation of the 351M engine has resulted in the 400 mistakenly being referred to as the "400M" or "400 Modified," despite having been the design basis from which the "modified" 351M was derived. Additionally, while the 351M and 400 motors are both based on the Cleveland block, Ford's official name for the block contains no additional designations - the proper nomenclature is simply "400."
- Schoenberger, Robert (3 May 2012). "Ford to close Cleveland Engine Plant No. 2, home of the iconic '351 Cleveland' engine". The (Cleveland) Plain Dealer. Retrieved 4 May 2012.
- Only 398 Ford Mustangs with the 351C HO engine were produced according to production data from Ford
- "Muscle Car Engine Shootout - Ford Boss 351 Vs. Chevy LT-1 350". Hot Rod Magazine.
- Heitz, Rudolf, ed. (1 August 1986). Auto Katalog 1987 (in German) 30. Stuttgart: Vereinigte Motor-Verlage GmbH & Co. KG. p. 120.
- "Geoff Infield's Ford V8 page". Archived from the original on 18 February 2006. Retrieved 25 July 2006.
|Ford Motor Company engine timeline, North American market, 1950s–1970s — Next »|
|4-cylinder engines||Ford Pinto engine|
|I6 engines||Flathead I6||Thriftpower I6|
|Mileage Maker I6||Truck I6|
|V6 engines||Cologne V6|
|Small block V8||Flathead V8||351 Cleveland V8|
|Ford Y-block V8||335/Modified V8|
|Medium block V8||FE V8|
|Big block V8||Lincoln Y-block V8|
|MEL V8||385 V8|
|Super Duty V8|