351 Cleveland

Let’s start with a general overview, specifically an aid in identifying the Cleveland engine. Before the 351C, there was the 351W which was a 351ci capacity version of the original Windsor engine family - so-called because that is where the original engine factory was, Windsor, Ontario - which started life as a 221ci in 1962, but grew to encompass the famous 289 and 302ci versions through the sixties.
In these small capacity displacements, the 289/302 was a great little engine - and it went on to become even greater in the eighties and nineties - but as car size increased in the U.S. Ford decided that they needed larger capacity from the small block to generate more torque to move the heavier cars. Hence they developed the 351W, but even from its inception, Ford appreciated that while the 351W gave the capacity required, it was a marginal engine from the point of view of developing more and more horsepower as the performance wars of the late sixties escalated. So Ford designed the 351C.
The 351C was designed from the top down with the major ammount of effort put into designing the best and most efficient cylinder heads that they could to allow the engine to breathe, and so to rev.
The 351C has a canted valve cylinder head, with splayed valves set at slight angles to one another, unlike the 351W which has parallel valve stems. This canted valve arrangement makes the 351C cylinder heads bigger - wider - than those of the 351W, and as a result it has wider rocker covers. As an aid to identification, the 351W exhaust manifold to cylinder head surface is almost vertical as viewed from the ends of the engine, whereas the 351C has an exhaust manifold to cylinder head surface which sits at 45 degrees and is as near parallel to the side of the block. This can be difficult to see if an engine is in place.
So, the other easy means of 351W to 351C differentiation is to know that the 351C has a dry inlet manifold wherein cooling water does not pass from head to head through a passage in the manifold, but instead passes across the engine in a cast extension to the front of the block. This extension also provides a ‘recess’ for the timing chain and contains the thermostat housing. Simply put, the top radiator hose for a 351C goes vertically into the thermostat on top of this extension, and the 351W top radiator hose goes in horizontally to its thermostat as fitted to the front of the inlet manifold.