Knock and Pin like noise
 

My 1990 Accord's engine is making noise like when timing is too advanced. When I go over 2000-2500 rpm it begins making this noise. If I'm driving slow and even going too slow on a high gear it doesn't make the noise but it does when I'm accelerating, hard or mild acceleration doesn't matter, it makes the noise.:wtf:
What could this be? I check the timing not to long ago, I can recheck but I think it is O.K.
Any ideas?