your timing chain is out of time. you are hitting the valves.
here is a diagram for the timing chain setup.
you align the colored mar on the chain with the alignment mark on the pulley as show in the diagrams.
you need to re assemble it in the correct time, then see if it is ok then.
dont wory too much about the timing advance thing. just make sure you line up the marks where they are sopposed to be on the sprocket.
DO NOT take apart the sprocket. you can take it off the camshaft, but DO NOT take it apart.
make sure your colored marks on the chain match the spots on the gears.