a Bigger cam will have more duration / overlap
yeah, that's where Engle was going. You will "bleed off" the pressure at lower rpms, raising the threshold (hopefully) beyond where you have it now. 452 heads have that huge chamber. Have you tried any decarbonizing stuff? Carbon build up in the chambers creates hot spots that could be working against you too. Water in a mist-it bottle works great for that...So does ATF (dosed carefully). Plugging in guestimate values on teh dynamic calculator, I'm coming up with a touch over 8:1 dynamic ratio. That should be OK on pump fuel. So, you may have oil leaking into the chambers from rings or guides, or and intake leak (lean and/or oil) or carbon buildup, or lean jetting, or too fast an ignition curve for your car/fuel type. I think mechanically speaking you should be fine. So I would first do three things. pull the plugs when it's hot(all
, and get a cranking compression reading from various cylinders. Look at teh plugs...are any wet with oil, or have large amounts of soot or carbon on them? Last, put them back in, get it hot again, and while holding the throttle open and keeping the revs around 1800, spray a full mist it bottle of water down teh carb...It may sputter and it should pump a lot of steam out. Then take it for a couple full throttle under load (like up a hill on the highway) balsts. You should see a big cloud of soot come out at first. if the cylinder psi reading is higher than 180, you need to either replace or retard the cam, or remove compression. If it's under 180, you should be able to tune out the ping on high test.