I've been running a 117 for two seasons. It continues to collapse a lifter in the 4500-5000 range when I lay into it hard on the front cylinder. I was told that the oil is foaming and not pumping to the front cylinder. It was suggested that I switch to Vic oil and only use 4 quarts, which did not resolve it...anyone have experience with this? Only happens on the front cylinder, I'm thinking I about changing out the lifters/rocker assembly's....