Hi guys, i need some help. My motor started knocking after a race last week. I found that after pulling the pushrods out of #7 the knock went away. So, I pulled the heads today to replace stock the lifters just in case they were the problem. But, once I had the head off I noticed that 3 valves have damage to the tips.

One has some pitting and is a bit mushroomed. Another has a valley beat into the tip. And the last is just beat up and a little mushroomed also. The rocker has also been hitting the retainer on this valve.

Specs are in my sig. AFR was good during the run, but there was a fair amount of KR. Any idea on the cause?