i knew headgasket job would be a bit of work. i thought the knock sound was maybe lifters and could check them when heads were off. a number were gummed up good so i thought maybe cleaning them would fix noise. parts wear on all motors and 1 car with 140k miles might be quiet while another is noisy. will different lifters and rockers result in same noisy motor? might be some worn wrist pins or rod bearings. i really dont want to put in a remaned motor but a used motor kinda bites too