engines noises

I got a 94 z28 with 100 000 miles on it and just the other day it started making this chirping or squeling sort of noise which seems to becoming from the back of the engine on the passenger side.
Ive checked the flex plate cause i thought it might becoming from lower, and nothing seems to be hitting it and its not cracked or anything.
Now i have taken off the valve cover and checked all the rocker arms and pushrods on the passenger side everything seems normal.
It still makes this noise after i put it back together i have no other ideas what it could be any help would be appreciated.
Also it doesnt knock or sound anything like that im wondering if make something with one of pistons if its scored or a skirt broken.
THats all i can tell you if you guys have any ideas or a simalar problem happen anything that can steer me in the right direction.

Does this noise happen to come on at random times when useing power, i.e lights or excessive use of the battery like leaving the door open or something....Because a whining noise comes from my passengers side and it sounds like its from the area of the altanator. But it also comes on at random times...getting more common, so yeah

I tell you what to do, if you think the noise is coming from inside the engine get a stethoscope and take the end off (you know the bowl looking thing) and get a punch (the tool) that will fit just in the hose of it… Put this on and go probing around in your engine for the noise at the loudest point is where you problem is…

its not my alternator its back further and i tried that stethoscope thing the motor is to loud around there to pin point where its coming from

do you think a little squel or chirp like that could be a rod bearing?

If it makes that chirping noise while it's idling in park, it might be your harmonic balancer.

yeah it makes it in park and while driving no differnce in the noise while driving

do you think this could be a spun rod bearing