HI!
Pay VERY careful attention to the cam timing, the marks are hard to see from above and can be out by as much as a tooth, this WILL cause valves to just kiss the pistons, don't fret I have seen several do this and no damage resulted surprisingly
The noise is like a ALL of your valve clearances being too loose, an obvious mechanical knocking similar to excessive timing advance.
Hope this helps.
JC
Pay VERY careful attention to the cam timing, the marks are hard to see from above and can be out by as much as a tooth, this WILL cause valves to just kiss the pistons, don't fret I have seen several do this and no damage resulted surprisingly
Hope this helps.
JC