I put this new cylinder on my D16z6 (the cylinder head is from a ZCD16A), and when it runs, it makes a loud knock. We tried adjusting the Cam timing (cause maybe the piston was hitting the valve), but it still knocks. We lined up all the cam, and crankshaft marks. I'm really stumped on this one. Any input would help. The only other thing I can think of is the piston-to-valve clearance, other than that I don't have a clue.