Posted by Brian in Oregon on Tuesday, July 16, 2002 at 9:28PM :
In Reply to: Re: Never seen Ford 400 posted by JeffS. on Tuesday, July 16, 2002 at 9:03PM :
The Ford 351C (C = Cleveland) was a medium block design that was supposed to replace the 351W (W = Windsor), which was based on the 302. The 351C was a new design, and looks quite similar to the larger 429 and 460 (indeed, some parts interchange). The basic differences are that the 351C block has a cast in timing chain cover, while the 351W uses a bolt-on aluminum cover. The head design is quite a bit different. The 351W is a wedge design that uses inline valves and rectangular ports, while the 351C uses poly heads with canted valves and oval ports. Interestingly, with some machinework and welding, 351C heads will fit a 351W.
The 400 is a 351C with a taller deck. The 351C was dead by this time as a performance engine, like so many others due to the so-called energy crisis, pollution controls and stiffening insurance costs. Ford found, though, that the 351C still had a market. So not wanting to have two different designs, Ford destroked the 400 to make the 351M. Basically the 351M is a 351C with a taller deck, resulting in excessive weight for a 351.
A few years go by, and the 460 takes over from the 429, which itself was displaced by the 400. Ironically, the 351M was then axed in favor of an older design, the 351W, because the 351W weighed a lot less than the 351M and this helped with fuel economy. So the V-8 lineup was 302, 351W, 400 & 460.
NASCAR 351 based engines are now a hybrid of the 351W and 351C. It is basically a hybrid of the 351C 4-bolt block and the heavy wall 351C "Australian" block, but it has the aluminum 351W timing chain cover, which makes up for the extra weight of the wall thickness. This is one of the 351 blocks Ford's SVO (Special Vehicle Operations) sells.
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