yeh. The video says valve knock but I had no clue what the noise was at the time but I know it is under the #4 piston somewhere. It is all going to be redone in my quest for more power. I just want to make sure that nothing in the block is damaged. I'll probably reuse my E-88 but give it a little porting, polishing etc...maybe get my cam reground to a fatter lift while I am at it. I was reading my how to rebuild and modify your nissan OHC engine and there was a mention about asymetrical cam lobes. Is there anybody that can do that on a regrind?