Editing Ford 335 engine (section)

===History===
The genesis of the "351 Cleveland" resulted from Ford's inability to produce enough of its new [[Ford small block engine]]-based [[Ford small block engine#351W|351 cu in]] V8s at its Windsor Engine Plant #1 in Windsor, Ontario, Canada.  Sales and marketing forecasts for the 1969 model year called for a second line, which was organized at Ford's Cleveland, Ohio, engine works.

At this time, it was also decided to upgrade the design of the new Cleveland manufactured 351s to improve performance.<ref name="Cleveland"/> Two cylinder-head designs were developed, one similar to the 351W, but with larger ports and valves, and the other with very large ports with canted intake and exhaust valves similar to the big-block [[Ford 385 engine|Ford 385 series V8]]. Sales, marketing, and product planning favored the canted valve design, as it was viewed as more innovative.<ref name="Cleveland"/><ref name="CC 351C"/>

Other changes to the engine were related to ease of manufacture and improved reliability. This led to elimination of coolant flowing through a 'dry' intake manifold, a potential source of leaks and minimized unnecessary heat transfer. To perform this change, the front of the engine block was extended to include provisions for the coolant to flow through a crossover in the block. This extension also acted as an integrated timing chain housing. The timing chain housing was covered with flat steel that was easier to seal than the typical large timing chain cover used on other Ford V8s.<ref name="Cleveland"/> These changes resulted in a bigger and heavier engine block than the small block V8s.<ref name="CC 351C"/> To help reduce costs the oil system was revised, as explained above. Although the 351W began as the basis for the 351C, by the time it reached production the design changes resulted in almost no parts interchanging between the two designs. The two engines, however, shared the same bore spacing, engine mounts and bell housing pattern.

The '''351 Cleveland''' began production in July 1969 for the 1970 model year.<ref name="CC 351C"/> Its actual displacement was {{convert|5766|cc|CID|1|order=flip}}. A conventional two-barrel "2V" (two venturi) version and a four-barrel "4V" (four venturi) performance version were built. The 351C-2V was never marketed as a high-performance engine. It used the small port 2V cylinder heads with open combustion chambers to produce a more economical passenger car engine that was tuned more for low-rpm torque.<ref name="V8Workshop"/> The 351C-4V was marketed as a high-performance engine, featuring the 4V large ports heads with closed "quench" combustion chambers. Later versions of the 351C with 4V heads continued to use the large ports and valves, but switched to open chamber heads in an effort to reduce engine emissions.  Only the Q-code 351 "Cobra Jet" (1971–1974), R-code "Boss" 351 (1971), and R-code 351 "HO" (1972) versions have four-bolt main bearing caps,<ref name="V8Workshop"/> however, all 335 series engines could be modified to have 4-bolt main bearing caps.<ref name="CC 351C"/>