Editing Ford 335 engine (section)

==Overview==
The 335-series V8s were [[overhead valve]] [[V8 engine]]s that used a unique short-skirt engine block that was both longer and heavier than that of the existing [[Ford small block engine|Ford small block V8]]. The 335 series incorporated features used on the [[Ford 385 engine|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.<ref name="V8Workshop"/> These engines use a shallow poly angle combustion chamber rather than the wedge style used on the small blocks.<ref name="CC 351C">{{cite web |title=The Ford 335 Series V8 Engines (351C, 400, 351M) – It Could've Been a Contender |url=https://www.curbsideclassic.com/blog/engines/the-ford-335-series-engines-it-couldve-been-a-contender-part-1/ |website=Curbside Classic |publisher=Curbside Classic |access-date=22 February 2020}}</ref> The 335 engines use large main-bearing caps, with two-bolt as standard and four-bolt added on some performance versions.<ref name="V8Workshop"/><ref name="CC 351C"/>

The first engine in the 335 series was introduced in late 1969 as the 351C. The 400 cu in appeared in the third quarter of 1970, which raised deck height from {{cvt|9.206|in|sigfig=3}} and tall deck {{cvt|10.297|in|sigfig=3}} to accommodate a longer stroke, and used larger main bearings for additional strength.<ref name="CC 351C"/> This was similar to the changes made to convert a [[Ford Small Block engine#302|302 Small Block]] to the [[Ford small block engine#351W|351 Windsor]].<ref name="V-8 Data Book"/><ref name="CC 351C"/> 

For the 1975 model year the [[#351M|351M]] replaced the 351C in North American markets.<ref name="V-8 Data Book"/> Initially Ford of Australia imported US made 351C engines. However, by November 1971, Ford of Australia began to manufacture the 351C locally at the Geelong Foundry. This engine was very similar to the American counterpart and remained in production until December 1981. Ford of Australia also produced a smaller 302C alongside the 351C, which was exclusive to the Australian market.<ref name="Cleveland"/>

===Comparison to Ford Small Block V8===
{{multiple image |align=center |direction=horizontal |header_align=center |caption_align=center |footer_align=center
 |image1=Clevelandblock.jpg |width1=250 |caption1=Cleveland block
 |image2=Windsorblock.jpg |width2=222 |caption2= 302 Block
}}
All 335 series engines shared the same {{cvt|4.38|in|sigfig=3}} bore spacing and cylinder head bolt pattern as the Small Block V8 family. There are a number of significant differences between the two engine families. The 335 series have a roughly two-inch extension cast into the front of the block which forms an integrated timing cover enclosure covered by a piece of flat steel, similar to an [[Oldsmobile V8 engine]]. This results in the 335 series engine block being heavier than the Small Block series engines'.<ref name="CC 351C"/> The 335 series use a dry intake manifold with the radiator hose connecting vertically to the cylinder block above the cam timing chain cover. Small Blocks use a wet intake manifold which routes coolant through the intake manifold via a horizontally protruding hose. The 335 uses smaller, 14mm, spark plugs and has a square-shaped eight bolt rocker cover while the small block's six-bolt rocker cover is more rounded.

===Oil system===
To reduce production costs, Ford eliminated one of the 335 series's main oil galleries from the block casting, leaving two compared to the Small Block family's three.<ref name="Car Tech Lubrication">{{cite web|last1=Cartech|title=Ford 351 Cleveland Engines: Lubrication|url=http://www.cartechbooks.com/techtips/351-cleveland-lubrication/|website=Car Tech Auto Books and Manuals|access-date=15 June 2014}}</ref> 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.<ref name="Car Tech Lubrication"/> The two main oil galleys in the 335 series engine run along the lifter bores. Oil is fed from the filter to the number one main bearing followed by the number one cam bearing above. At the same time, it also feeds the right hand oil galley, supplying the right side lifter bank. It has four galleries that lead to each of the remaining main bearings. After the oil feeds them, it feeds each corresponding camshaft bearing above. At the rear-most main bearing, the oil goes into the second gallery, which feeds the left lifter bank.<ref name="Cleveland"/><ref name="Pantera 351C Tuning">{{cite web|last1=Pence|first1=George|title=351C Basics and Performance Tuning|url=http://pantera.infopop.cc/eve/forums/a/tpc/f/5650045562/m/319104265|website=Pantera International|access-date=15 June 2014}}</ref> 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.<ref name="CC 351C"/>

===Cylinder heads===
The cylinder-head design for the 335 series engines is its most definitive design feature. All cylinder head variants were two-valve that use large free flowing ports with poly-angle or 'canted' valves.<ref name="V8Workshop"/> Having the intake and exhaust valves at separate angles allowed for very large valves to be used while reducing the port length and minimizing sharp turns within it,<ref name="Pantera">{{cite web|last1=Pence|first1=George|title=The 351 Cleveland Cylinder Head|url=http://pantera.infopop.cc/eve/forums/a/tpc/f/5650045562/m/4131047336|website=Pantera International|access-date=1 June 2014}}</ref> creating freer flowing heads than the Ford small block V8s.<ref name="351CHeads">{{cite web|title=351C heads|url=http://home.comcast.net/~jelerath/mustang/Specs/heads-fr.html|access-date=1 June 2014|url-status=dead|archive-url=https://web.archive.org/web/20131224193845/http://home.comcast.net/~jelerath/mustang/Specs/heads-fr.html|archive-date=24 December 2013}}</ref>

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.<ref name="CC 351C"/> The ports and valves on 2V heads were significantly larger than small block engines<ref name="351CHeads"/> and had excellent flow - actually slightly better than 4V heads at lower valve lifts.<ref name="CC 351C"/> The 4V heads had enormous ports which flowed very well, in particular at higher valve lift, and could out-flow Chevrolet Double Hump heads and Chrysler's high-performance 340 heads.<ref name="CC 351C"/> 

In addition to the two port sizes, the 335 cylinder heads used two style of combustion chambers, an open or a closed "quench" chamber. Both combustion chambers are very shallow, due to the shallow valve angles. The combustion chambers are almost a very shallow hemispherical chamber, rather than a wedge shaped.<ref name="CC 351C"/> The closed chamber heads enclose the valves more closely, reducing combustion chamber volume, to increase the compression ratio. However, both designs have the same [[thermal efficiency]] and resistance to detonation.<ref name="Pantera"/> The closed combustion chamber promotes better swirling of incoming air fuel mixture, giving it a low-rpm torque advantage, and requires less machining to obtain high compression ratios.<ref name="Pantera"/> However, the open chamber heads valves are less shrouded, which improves low lift airflow,<ref name="CC 351C"/> and they exhibit better emissions characteristics.<ref name="Cleveland"/><ref name="Pantera"/>

Most 335 series engines used stamped rocker arms with cast fulcrums that made for a non-adjustable valve train. The rocker arm design was originally used by the Ford 385 series engines.<ref name="CC 351C"/> However, the [[Ford_Mustang_variants#351|Boss 351]] and 351 HO had an adjustable valve train, using rocker arms mounted on screw-in studs and guide plates.<ref name="Cleveland"/><ref name="DIY Ford Valvetrain">{{cite web|title=Ford 351 Cleveland Performance Guide: Valvetrain|url=http://diyford.com/ford-351-cleveland-performance-guide-valvetrain/|website=DIY Ford|access-date=11 June 2014}}</ref>

Prior to the release of the 351C, the 335 Series cylinder head was used on the [[Ford Boss 302 engine]].<ref name="CC 351C"/> The Boss 302 used a large port closed chamber 4V cylinder head which required minor modifications to make the cylinder heads work with the 302 engine block.<ref name="Cleveland"/> The Boss 302 version of the cylinder heads used small 58cc cambers and large 2.23" intake valves. The valves were later reduced to 2.19" as used on the 351C 4V cylinder heads.<ref name="CC 351C"/>

{| class=wikitable align=center
|+'''335 Series V8 engine cylinder heads'''<ref name="Cleveland"/><ref name="V8Workshop"/><ref name="351CHeads"/>
|-
!Head type!!Chamber type!!Chamber volume!!Intake valve!!Exhaust valve!!Intake port!!Exhaust port||Application
|-
|2V||Open||74.7 - 79.9cc||2.04"||1.65"||2.02" x 1.65"||1.84"x1.38"||351C-2V, 351M, 400
|-
|4V||Closed||61.3 - 64.3cc||2.19"||1.71"||2.50" x 1.75"||2.00"x1.74"||1970 351C-4V
|-
|4V||Closed||64.6 - 67.6cc||2.19"||1.71"||2.50" x 1.75"||2.00"x1.74"||1971 351C-4V
|-
|Boss 351||Closed||64.6 - 67.6cc||2.19"||1.71"||2.50" x 1.75"||2.00"x1.74"||1971 Boss 351
|-
|351C-CJ||Open||73.9 - 76.9cc||2.19"||1.71"||2.50" x 1.75"||2.00"x1.74"||1971-72 351C-CJ
|-
|351C HO||Open||73.9 - 76.9cc||2.19"||1.71"||2.50" x 1.75"||2.00"x1.74"||1972 351C HO
|-
|351C-CJ||Open||73.9 - 76.9cc||2.04"||1.65"||2.50" x 1.75"||2.00"x1.74"||1973-74 351C-CJ
|-
|Australian 302C||Closed||56.4 - 59.4cc||2.04"||1.65"||2.02" x 1.65"||1.84"x1.38"||302C
|}