Rhino

iTrader: (6)

That is interesting. I'm not sure what the lobes are, however I do know they're pretty aggressive. I'll make a call tomorrow to see what I can find out.
I'm typically one that doesn't like relying on a shop, but I'm stumped. I'm almost ready to take it to someone just to have another set of eyes on it.
Is it possible that the noise I'm hearing now is the lifter cup bottoming out as the valve opens? I plan on pulling the thing apart again and re-measuring preload with a dial indicator to truly see where I'm at.

The other thing I'm contemplating is getting a set of 8 7.325 pushrods for the intake side. In that same thread you referenced another guy mentioned everything being noisy at 2 turns. I hate to buy another set of pushrods, but I'm not sure what else it could possibly be.

Rhino

iTrader: (6)

Out of pure frustration and a few people's suggestions, I tried the stock 7.4's yesterday. IMO that's an insane amount of preload, but figured it couldn't hurt to try short term. I think the engine is again a slight amount quieter, but still retains the exact same noise.

I'm not sure what else it could be, other than valve train noise. I've listened to the bottom end and feel it can't be coming from there. All I really hear is a gentle whirring noise that I would expect. I did also try unhooking each coil pack individually to see if it went away. It truly doesn't sound like anything on the bottom end, but figured I've been checking everything else...

This morning I did get a response from the cam designer. He verified that it is on a stock base circle. Given the LS7 cup sits .050 higher in the lifter, only a small mill for cleanup, and a stock MLS gasket, I feel pretty confident that the 7.350's should work. That also does back up my measurements taken by the adjustable pushrod. I'll be putting them back in and swapping out the rockers with another stock set I have since I'm running out of other things to test.

I called up a local shop to see what their schedule was like. I'm really interested to get another set of eyes and ears on this thing. It sounds like they'd be at least a few weeks out so I have some more time to kill while racking my brain. Any other suggestions are very welcome.

01ssreda4

iTrader: (96)

Good luck finding the problem OP. Headers in an Avalanche

69LT1Bird

iTrader: (1)

Just for the fun of it have you tried unplugging the injectors one at a time. I have seem injectors make a hammering type sound if the poppets have issues inside of them.

Rhino

iTrader: (6)

Thanks! I figured I should do whatever I can do to get this 5800 lbs pig to move out of it's own way. It's generally my DD, I'm just trying to wake it up a little and make it a little more tolerable when towing my car. With a trailer behind it, the 5.3 was a little gutless.

I haven't yet, however that is a good idea. I did listen to them with a stethoscope and nothing popped out at me. Unfortunately, with the scope I'm picking up way too much other noise to know for sure.

I have been trading emails back and forth with the cam designer. After listening to the videos and my description he feels that it still needs more preload. He mentioned that he has a lot of customers with this cam use 7.450's. It seems like too much preload to me, but I'm running low on other options and he sounds pretty sure that it would resolve the issue. From what I've determined that would be a total of .100 over stock preload (+.050 and the difference in the stock to LS7 lifter). Is that even possible on these lifters?