[WILMASBOYL78]

Originally Posted by big gear head

My 427 is a true 11:1 engine and I'm running 91 alcohol free fuel in it with the timing turned down to 35 degrees. When I go to the track I use 110 with the timing at 39 degrees. No problems so far. I have open chamber aluminum heads which may make a difference.

I would say those open chamber aluminum heads will definitely make a difference. Your actual compression is probably closer to 9:1 and aluminum allows for better cooling, so detonation isn't as much of an issue.