The other day I was trying to adjust my timing chain because I thought it had stretched. I tried to fire up the engine and it would not go I kept playing but I could not get it any better. A funny noise came from the engine it sort of sounded as if the valves were hitting the pistons (is this possible?) one of the valves is now stuck down I think it is bent. Also the crank will no longer turn I don't know what I have done. As soon as I get some spare time I'll take the head off and fix the valve any other suggestions as to what I have done would be great. Also could someone please tell me how to get the timing chain back to the correct position.