Its not piston slap for sure, the sound coming from the v/v train (driver side).
it 'd be either; bent pushrod / a bad rocker arm, however the engine running fine!

If so ... what should i do? replacing the defective parts only or replacing all valves, pushrods, springs...???

another q: if i leave it with no repair what will happen?

thanks in advance

 

Most likely a pushrod. I had one do that and it wasn't bent, just in a bind.
Just pulling it out and slapping it back together fixed it.

 

My 02 SS has the same noise! It's at camshaft speed and sound's like from bank 1 V/C. Let me know when you figure it out!!!!!

 

You can change bad pushrods or lifters on a one for one basis with no ill effects.
Valve springs should only be changed as sets.

 

Thanks alot guys,
so in this case i think i'm going for stiffer rate springs what do u think?

 

Thank guys,
in this case i think i'm giong for stiffer rate springs, what do u think?

 

I would check all the exhaust manifold / header bolts to be sure they're tight and look for any holes in the exhaust gasket before taking the valve covers off and readjusting rockers. An exhaust leak will make a ticking sound.