Big Blocks

Actually at high RPM's the cylinder leans out due to over scavenging due to overlap, and this causes the detonation, making a lean mixture.
Cam specs. in the 100+ overlap and durations in the 265+ @ .050.

What happends is when the timing is right to make the car leave and run then becomes too much on the top end and crates a lean condition. But if you retard the timing from the get go then the car becomes lazy and won't run down low. I just went through this on my 344 engine with 107* of overlap, and it burned every piston, on alcohol.