When I was towing my big block back from Mi with my mustang, I ran into pinging problems when I hit the uphill grades on the NY thruway. The Gas that I had filled with was 87 octane with 10% ethanol. Even though alcohol has more octane, it also has less btu/gal and burns at a lower air/fuel ratio. something like 6:1 vs 14:1 for gas, this is why alky carbs have giant jets. So.. adding 10% alcohol to gas is like watering it down, and can cause some leaning out. I had to fill up with some 94 Octane before I got to Mass since there is a high elevation pass.
Running more Ignition lead will feel like more compression since it builds cyl pressure. But.. it is different, the fuel is still burning longer, and more compression does probably give more power than low compression and more timing.
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