http://youtu.be/BaV6rtoeWhk

Does this sound bad? Are we damaging something? A collapsed lifter sounds way worse right?

 

I cant hear nothing but a good running LT1.

 

sounds similar to a "sticky" accessory belt? pull it off, then run it and eliminate that possibility.

 

I'll try taking the belt off, but it definitely seems to be coming from the drivers side valve-cover. It could maybe be a leaky exhaust gasket, but its weird and inconsistent:
Tap,___Tap,Tap,Tap___Tap___Tap___Tap,Tap,Tap,Tap___Tap___Tap,Tap that kinda thing.

 

Pull the valve cover and watch. As long as you let the car idle you should be able to see whats going on easy without making a mess.

1. valvetrain - rockers/pushrods/lifters tapping here and there.
2. exhaust leak
3. vibrating engine banging into things. Headers could be tapping the k-member etc.

Can you see the engine move in rhythm?


Also... just so you know, I dont know if it's a T56 car or not, but T56's in neutral (LT1 T56's especially) are known to make a horrendous clanking/knock similar to that while the engine is running. I've heard people say it's the pilot bearing, I've replaced mine both times I did my clutch, and it made no difference. I think it's the clutch fork banging around without any hydraulic pressure against it to preload it into place. In any case - it's harmless. See if it goes away when you push the clutch pedal in, doesnt even have to be all the way, just enough to put some tension on the fork. That makes it go away it seems, hence my theory. My car makes a VERY similar inconsistent tap/rattle noise from the clutch, but it's coming from under the car, not the valve cover, so who knows.

 

It's a t-5 behind it, so we can rule that out, also we've tested it with the clutch in and out. I also have a cut-out valve cover for adjusting the rockers, so we've seen it running before and have made sure all the rockers are tight while it's running. It could be an exhaust gasket, but it really seems to be coming from the top of the engine.
As far as vibration, I doubt it, but it could be something hard to see? It definitely increases with engine speed, but quickly gets drowned out. I guess if it gets louder, then we know we have a problem?