I don't mean to imply the 351C can't detonate ... the point I would like to make is the shallow poly-angle combustion chamber doesn't rely upon "squish" to prevent detonation, this is why the open chamber version of the 351C head is no more prone to detonation than the quench chamber version. There are some members who are under the assumption that the open combustion chamber will detonate easier than the quench combustion chamber, or is even prone to detonation, and that the open combustion chamber cannot possibly make as much horsepower. But those assumptions are largely unfounded and influenced by the fact they apply wedge combustion chamber characteristics to the 351C combustion chamber. To those who think that way I write the open combustion chamber heads can make as much power and they don't detonate (any more than the quench heads).
It is of course possible to get any engine combination so far outta whack that it will rattle, ping and detonate.
In the case of the 351M & 400 I think Miller hit the nail on the head, the extreme amount of deck clearance in the later versions of those motors destroyed the shallow combustion chamber's ability to swirl the mixture around. Stagnate pockets of air & fuel are what cause detonation.
Sometimes what we refer to as detonation isn't really detonation. Having worked on old Fords ... I can point a finger at one aspect that causes problems ... worn out or gummed-up centrifugal advance mechanisms that get stuck at full advance. Of course that's not really detonation, that's just too much advance. Pre-ignition (pinging) is another issue that's not related to combustion chambers. Ignitions and carburetors that are out of "whack" will of course create detonation sounding problems. Lean air-fuel mixtures, weak ignition modules, worn out spark plugs or cross-firing ignitions will do this.
All these problems occur when things are outta whack. But wedge heads are another situation. By their very design the portion of the cylinder farthest from the spark plug, directly below the squish area of the head, is completely shielded from the flame front. Pockets of stagnate fuel and air collect there easily at low rpm. Wedge head motors can go into detonation even when everything is well maintained and seemingly working properly. This situation will not happen with a 351C unless ... as Miller pointed out ... the deck clearance is extremely large.
-G
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If you use a 351C 4V powered vehicle for a grocery getter ... the eggs aren't going to make it home!
