Lt-4, rebuilt to 383,25,000 miles on rebuild, had a comp cam (mild)installed when rebuilt. Started having problems with oil leaks around valve covers. I took to a shop for inspection. Shop calls and all valve spring dampners are broken. Heads sent off for repair, arp studs installed, new gaskets, get car back runs fantastic for 20 miles, then sounds like lifters are not pumping up, lots of ticking noise.
Go to start up yesterday and I hear a bad knocking noise coming from heads. I'm at a loss. Any ideas? This has got to be the most expensive engine rebuild and repair.

Who adjusted the rockers when the heads went back on? Valve lash might not be correct.

Also, did you get springs, etc suited for your cam?

Are the ends of the push rods mushroomed? Blocking oil flow?

Could debris have gotten into the engine during the repair, blocking oil flow?

I would start by looking at your cam. Get the specs from the guys who installed it and make sure its the right one. As an after thought you might also consider upgrading your oil pump. Good luck.

You said your "Valve spring dampners are broken"?
All 16 ! Imho, I would make sure you have oil squirting
out of all pushrods,check for coilspring bind/clearance,correct valve train geometry etc...
Start at the cam & work your way up

Sounds like valves are not adjusted correctly, yet valve spring failure acrossed the board is an entirely different issue.
I would like to see the other guys chime in on this!

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Issue resolved. Took the car back to the new shop I go to. One lifter was not pumping up. Lifters replaced. The original spring issue was based upon the original engine builder at one of the top 100 corvette shops in the country supposedly put in comp cam springs matched the comp cam. When the heads were pulled, the shop suspects the springs were not comp springs. The springs that were pulled out were bee hive style. The shop (well known in DFW) thinks the springs put in when the engine was rebuilt were cheap china copies.
Same with lifters, not replaced but on the build sheet as new. Many other issues were resolved with the new shop. The owner specializes with LSx transplants into everything from Miata's to Nissan 350s. The owner specializes in the LTx also. Great shop.
Now, for the original repair I have been trying to complete for a year, the Banski rear end.That will be the February work!!

Glad you got it resolved! Sorry to hear the first "reputable" shop screwed you!!!

I'm happy to read that you are moing forward through a difficult situation. Keep us posted on your progress.

The original shop may have done nothing wrong. I seem to recall a couple years ago comp cams switched to a different supplier for their 918 behives and there were a bunch of failures.

Mike