Sound was not from head but from some rubbing of nut of gear box/engine rubbing with frame. Upon accelerating engine, that nut was rubbing with frame, causing grinding sound. I will try to post pics of that nut. That nut is below some where around area where engine and gear box are connected.
Being fact that all mounts were changed, engine was supposed to be little upward so that there was no such rubbing of nut with engine frame. Mechanic did some hitting on frame and created little gap between nut and frame. And problem solved. No such sound now.
This approach is not right. I should have gone for root cause of why engine was below its actual place.
Anyways, for time being problem is solved. Sometime later, I will go for its root cause of why engine is below its actual level even after replacing all mounts.
@tahasoomro, thanks but I could not visit Ajmal.