In Canada, we can basically get 3 types of premium gas, 91 Octane (Shell), 93 Octane (Esso) and 94 Octane (Petro Canada).  The Shell 91, has NO Ethanol in it, but both the higher octane fuels have as much as 10% ethanol in them.
Now my question is this: I have recently run into head gasket problems due to detonation taking out the fire rings in my motor. This was caused by my distributor and has since been cured by a new MSD distributor. However, my engine guy recommends the higher octane, since I am at 10.5 to 1 compression. My concern is when I ran ethanol based gas in the past, I ran into carb problems (float sticking). Not sure if this is still an issue as I have switched to a new Holley Avenger (2 years ago)?  Thoughts.........anyone?