The Ford 335 engine was a family of engines built by the Ford Motor Company between 1969 and 1982. The "335" designation reflected Ford management's decision during its development to produce a engine with room for expansion.
The 335 series engines were used in mid- and full-sized cars and light trucks, (351M/400 only) at times concurrently with the Ford small block family 351 Windsor, in cars. These engines were also used as a replacement for the FE V8 family (1958–1978) in both the car and truck lines. The 335 series only outlived the FE series by a half-decade, being replaced by the more compact small block V8 family.
Overview
The 335-series V8s were overhead valve V8 engines that used a unique short-skirt engine block that was both longer and heavier than that of the existing Ford small block V8. The 335 series incorporated features used on the 385 big-block series, including the canted valve layout, the valve train design, and thin-wall casting technology. All 335 series V8s had free breathing, large-port canted valve heads with a rugged engine block. The 335 engines use large main-bearing caps, with two-bolt as standard and four-bolt added on some performance versions. The result was an oil system very similar to the 385 series V8s, adequate for street engines but falling short in high-revolution race use without modification. In addition the oil system not prioritizing the main bearings, the 335 engines have excessive clearances in the lifter bores. This results in oil leaking out of the lifter bores which can cause oil cavitation from the lifter motion, and can reduce oil flow to the main bearings. creating freer flowing heads than the Ford small block V8s.
The 335-series engines used different cylinder heads for two and four barrel carburetors. The 2V (two carburetor venturi) small port cylinder heads were used on 2-barrel engines while the 4V (four venturi) large port cylinder heads were used on the 4-barrel engines.
Prior to the release of the 351C, the 335 Series cylinder head was used on the Ford Boss 302 engine. H-code 351s were equipped with a cast-iron crankshaft, two-bolt main bearing caps, forged-steel connecting rods, cast-aluminum pistons, non-adjustable valve train, and cast-iron intake and exhaust manifolds. All H-code 351 Cleveland engines used the small port 2V heads with open combustion chambers.
M-code
The M-code was a high-compression, high-performance variation of the 351C, produced in 1970 and 1971. The M-code engines used the large-port 4V heads with a closed "quench" combustion chamber and large valves.
(Boss 351)
thumb|right|1971 Mustang Boss 351, the synonymous Ford model the R-code was built for
The Boss 351 was the most potent high-performance variant of the 351C available only in the 1971 Boss 351 Mustang. Rated at 330 bhp (246 kW), it was fitted with a four-barrel Autolite model 4300-D spreadbore carburetor, an aluminum intake manifold, solid lifters, dual-point distributor, a six-quart oil pan, and cast-aluminum valve covers.
The January 2010 issue of Hot Rod 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-inch 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 externally modified state it produced SAE gross at 6,100 rpm, and torque (gross) at 4,000 rpm. A measurement of SAE net horsepower would be significantly lower, and represents a more realistic as-installed configuration with all engine accessories, air cleaner assembly, and automobile exhaust system.
(351 HO)
The 351C HO "R-code" had a number of changes to help meet emission standards for 1972 compared to the 1971 Boss 351 "R-Code". The camshaft had less duration, but more valve lift, while the mechanical lifters remained unchanged. and the lower compression allowed regular fuel to be used. It was rated at for all 1971 applications. For the 1972 model year, the only change to the engine was a retarding the camshaft events by 4°.
Replacement
Production of the 351C ceased at the end of the 1974 model year. The engine was replaced by the 351M for the 1975 model year. This new variation used the same bore and stroke dimensions of the 351C, but used the tall deck block from the 400 V8 engine and was only available with a 2 barrel carburetor.
351C engine specifications chart
{| class=wikitable align=center
|+351 Cleveland engines
|-
!Code!!Engine type!!Years!!Compression!!Combustion Chamber!!Camshaft Duration!!Camshaft Lift||Tappets!!Main Bearing Caps||Notes
|-
!H
|351C-2V||1970–1974||Low||Open Chamber||258° I/266° E 32° overlap||0.400" I/0.406" E||Hydraulic||2-bolt||
|-
!M
|351C-4V||1970–1971||High||Closed Chamber||266° I/ 270° E 34° overlap||0.427" I/0.427" E||Hydraulic||2-bolt||
|-
!R
|351C-4V "Boss 351"||1971||High||Closed Chamber||290° I/ 290° E 58° overlap||0.467" I/0.477 E||Mechanical||4-bolt||Rare
|-
!R
|351C-4V HO||1972||Low||Open Chamber||275° I/ 275° E 35° overlap||0.491" I/0.491" E||Mechanical||4-bolt||Very rare
|-
!Q
|351C-4V CJ|| May 1971 – 1974||Low||Open chamber||270° I/ 290° E 48° overlap||0.480" I/0.488" E||Hydraulic||4-bolt||cam timing retard 4° in 1972, compression reduced in 1973
|}
400 and 351M
===400===<!-- This section is linked from V8 engine -->
By 1970 the 390 V8 FE engine was becoming outdated. With pending emission requirements, a more modern replacement was needed. Although the big-block 385 family was used to replace the larger displacement 428 V8 FE engine, this engine family had nothing comparable in size to the 390 V8. For the 1971 model year, Ford introduced the 400 V8 engine as a replacement for the 390 V8. Ford billed the 400 as the 351C's big brother. It was designed to provide brisk acceleration in medium to heavy weight vehicles in an engine package that was smaller and lighter than the FE V8 Engines and the 385 Series Ford V8's.
The 400 was designed as a high torque, low RPM engine that was a smaller, more efficient and lighter alternative for the big Ford 385 engines, the 429 and 460, for use in Ford's medium and large size 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 for the 1971 model year. For 1972, it was also available in the Ford Torino, Mercury Montego and its variations through 1979. By the late 1970s it was also available in the Ford Thunderbird, Ford F-series pickup trucks, the Lincoln Continental, and Mark V.
Unlike the 351C, almost all 400 blocks used the large bell housing bolt pattern used by the 385 family big-block and were typically equipped with the higher torque-capacity C6 transmission. There were a small number of 400 block castings produced in 1973 with the dual bell housing patterns. It had the large bell housing and the small bell housing bolt pattern used by the small block V8 family and the 351C, though it was not necessarily drilled for both. These particular blocks have been dubbed the "400 FMX" by enthusiasts, though were never officially referenced as such by Ford. Most 400's also had unique engine mount bolt pattern but these 400 FMX blocks had provisions for both 351C-style and 400/351M engine mounts. For 1972, the compression ratio was reduced through the use of dished pistons. The compression was reduced again for 1973 and a new timing set retarded the camshaft timing 6° to aid with reducing emissions. In 1971, this method of reducing compression was sufficient due to the higher-octane leaded fuels. However, once lower-octane unleaded fuels became used, the excessive deck clearance led to problems with detonation. For 1975, Ford dealt with this problem by decreasing the compression ratio further with a larger 15cc piston dish and reducing ignition timing. However, the 400 V8 obtained a reputation for being prone to detonation. until the introduction of the 7.3-liter "Godzilla" engine for the Super Duty trucks in model year 2020.
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, a manual transmission could be ordered for the first time with these engines. As a result, the block was strengthened in the main bearing supports, in particular the #3 support to better handle the loads imparted by the clutch. The truck engines had unique parts including pistons for different compression ratios from the car engines, truck specific intake and exhaust manifolds, camshaft with more lift, and timing set that did not retard the camshaft timing. The strengthened engine block was introduced to the Ford cars for the 1978 model year.
Block-cracking problems
The 400 V8s for the model years 1971–72 were either cast in the Dearborn Iron Foundry or the Cleveland Foundry. Those built for model years 1973–79 were either cast in the Cleveland Foundry or the Michigan Casting Center. Ford master part catalogs reference the engine as a Modified.
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." This is despite the 400 having been the design basis from which the "modified" 351M was derived and it was in production several years before Ford used the "M" designation. Further confusion arises from Ford printing "351M/400" on the emission stickers for the engine. The "351M/400" referenced the engine family, and some confused this with the engine name. This sticker also listed the engine displacement below the engine family. Ford's official name for the 400 V8 contains no additional designations - the proper nomenclature is simply "400." In the early 1970s before the 351M debuted, Ford referred to the 400 as the "400 Cleveland".
Replacement
The 351M and 400 were last offered in a Ford passenger car in 1979. They remained available in Ford light-trucks until 1982. Reduced demand for larger engines due to tightening CAFE regulations led to the abandonment of the 351M/400 and the Cleveland production line. By 1980, mid-sized V8's had disappeared from the option list for almost all Ford cars. Only the full-size Panther platform Fords had anything larger than 302 ci available, and this need was filled with the 351W. With low demand for engines in the size range of the 351M/400, the 335-series V8's no longer had a need to be produced.
In addition, there were difficulties adapting the M-block to the second generation of emissions controls. Unlike previous Ford engines, Thermactor and exhaust gas recirculation features had already been built into the 351M and 400 engine, rendering adaptation to electronic feedback fuel/air systems difficult. One requirement of the second-generation equipment was an oxygen (O<sub>2</sub>) 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 O<sub>2</sub> sensor to go.
302 and 351 Cleveland (Australia)
:Note that there was also a 302 "small block"
History
During the 1969 Model year, Ford of Australia imported approximately 17,000 302 and 351 Windsor V8's. However, the 351 Windsor was phased out for 1970 in favor of the newer 351 Cleveland. The 351 Cleveland engines continued to be imported from the US along with the 302 V8. Both the low-performance 351C-2V and the high performance 351C-4V were imported with the vast majority of the engines being the 351C-2V. Like the US engines, the 4V versions used the closed "quench" chambered heads and used the larger ports on the cylinder heads. The very last 351 Cleveland V8 engine made in Australia was installed in a 4WD Ford Bronco. More than 250,000 Cleveland V8s were built at Geelong in total, 12,020 of them being installed in commercial vehicles.
302 Cleveland
thumb|upright|An Australian factory-forged 302 Cleveland crankshaft in-situ. The number "302" confirms its intended displacement.
In November 1971, Ford of Australia began to manufacture the Cleveland engine at the Geelong engine plant alongside of the 351C. The engine remained in production until 1982 and was only produced in Australia. The 302C was considered an economy V8 and it is estimated that only ten percent of Australian Cleveland V8 production was the 302C.
The combination of the closed chamber heads with the small 2V ports has caused the 302C head to be a bolt-on-performance upgrade for other 335 series V8s. Having the smallest combustion chamber of the 335 series V8s, these cylinder heads will easily boost the static compression ratio of any other 335 series V8. In addition, the small ports used on these head are more efficient for a street performance engine than the large port 4V heads that tend to favour performance only at higher engine speeds.
351 Cleveland
Initially, the 351C was imported to Australia from the US. Both the 351-2V and 351-4V were imported and both were in all respects the same as the American market counterparts. In November 1971, Ford of Australia began producing its own 351C engines, ending the importation of American engines. At the outset, Australia only produced a 351-2V engine, but in March 1972 Ford of Australia began to offer a new 351-4V engine with a 4-barrel carburetor. Australia only produced one style of cylinder head for the 351 engines, a 2V head with small ports and open chamber cylinder heads. As a result, the Australian 351-4V engines used the 2V cylinder head. This required a unique 4V intake manifold with the smaller 2V ports, unlike the American 351-4V intake manifold which used the large ports.
See also
- Ford 385 engine
- List of Ford engines
Notes
References
External links
- Short descriptions of Ford overhead valve V8 engines
- M-Block Ford V8 Workshop