For sure some changes are in order as 210 cranking pressure is pretty high and tells you that it's closing the intake valve very early and dynamic compression will also be very high and at low rpm's.
The detonation thing happens much easier below and at peak VE because the events are happening much slower and in any N/A engine cylinder filling is more effective at low rpm's. Roller camshafts also contribute more to that deal as they will by design improve cylinder filling at relatively low engine speeds. Hence why the XR276HR cam is a HORRIBLE choice for a 455 Pontiac engine build with much past about 8.5 to 1 compression in it, and even then it's not enough cam to effectively use good flowing heads or make acceptable upper mid-range and top end power.
Nearly everyone in this hobby looks at everything "static", especially cam specs. One has to realize that as the rpms increase the time in milliseconds the valves are open decreases. So what we need to do is to concentrate our efforts to keep cylinder pressure low enough thru peak torque so we can manage pump gas with a "normal" tune.
This is best done with camshafts that have a lot of off seat timing, wide LSA and later intake closing. What this does to the power curve is to make it broad, flat and smooth. Camshafts with short seat timing events, tight LSA and earlier closing intake do just the opposite, they narrow up the power curve, higher peak torque and it will occur earlier in the rpm range. As you are finding out you also get the same result with a smaller cam even if it's out on a 112LSA. So two things work against us here as far as building a moderate compression ratio engine for pump gas, cam too small, and/or LSA too tight.
To date I've never used Dave's "Stump Puller" camshaft simply because most of the 455 engine builds we do here are at least 10.5 to 1 compression and the larger Old Faithful cam suits them much better.
There are other players in the "recipe" to effectively manage pump fuel than just the camshaft, but it is a "key" ingredient and when it's too small the engine really never has a fighting chance to make optimum power or effectively manage pump gas so we're shot down twice before we even get started.
I've also found that quench distance is a BIG deal here as well, as is LSA. For the big Pontiac engines we've found two things to be true in recent years. The wider we go with LSA the more power we are rewarded with, and the tighter the quench the less timing is needed to make best power and they manage pump fuel better. For this reason our street engine builds these days use higher compression, lots of off seat timing, wide LSA and quench is NEVER over .039" for any reason.....Cliff
