So I got a junkyard lq9. Me and 5 other people (I had multiple people look at it because it said cracked block all iver the car) checked it out and it looked really good. I tore it apart and put it all back together with some new parts. I finally got it running right one day. But the next day it was making an insane ticking noise. It sounds like an old diesel engine. I assume its knocking but maybe its a piston slap or a coil ark? I took the head covers off to check the rockers and they all move solidly. I wish I could upload just a video. But my metal i take also reverberates the sound a bit too. Any ideas what it could be?

 

Don't overlook the flexplate. They crack and make a clicking noise.

 

Lifters make a ticking noise while loose pistons make more of a knocking noise. If the bearing clearance on the rods is too loose, it could also knock.

Yes, Metal intakes will amplify some of the sounds.

With out a video or hearing it in person, it could be anything.