Nutshell....
Mine since new 2007 Z06., 84,000 mi. New heads, cam installed 18K miles ago. about 5 YRS ago. Late last year, needed to pull heads as it seemed that there was a faulty lifter that wiped out the 18K mile cam. My guy said that it happens sometimes. He commented that there was lubrication to the area and did not see any blockages. Had the work done again with new cam,lifters, etc, and put the car away for the winter after a few hundred miles.
Just drove it a few hundred miles more this summer, as my age and health has kept me indoors mostly. Driving home yesterday, I hear the lifter banging away AGAIN. Location, driver side first cylinder again!
Sounds to me like there is no lubrication getting to that lifter. Iam not going to start the car again until it gets towed back to the shop., hoping to at least save a brand new Comp .Cam.
Any ideas before I take it back to the shop for a go-round with the owner. If I am on the right track, then how does one diagnose the blockage. Please don't tell me "engine out, steam the block, blow out all passageways"......Is ther an easier way?
Any Help will be appreciated!

 

There can be a problem with roller lifters getting slightly turned if not held in place well. When they turn a little, they start to skid on the cam, and when that happens, the lifters and camshaft is shot in short order. Are your lifters OEM and held in place with the GM plastic plate? If so, how many miles on that plastic lifter plate? There is nothing wrong with the GM lifter plate, but if it is worn excessively, it will allow the lifters to turn. If you don't have OEM lifters, what type of lifters to you have, and how are they held in place so they don't turn?

 

The lifter tray being worn will allow some turning to occur. Saying you heard it banging though leads me to think the lifter pre-load was incorrect from incorrect pushrod length or even incorrect spring tension can be kicking down the plunger. It bangs if it is bottomed out. Do you have a picture of the cam with the worn lobes? I can tell from that.

 

As noted, this repair only has about 500 miles. The previous installation lasted about 18K miles. I know that my guy used GM parts and the same spec Comp Cam that was in it before. I will be meeting with him today or tomorrow to discuss options

 

As noted above, I will be meeting with my guy in the next two days to look at options. This motor has always been "quiet", so when the clacking started, along with the vibration of a "miss" in the shifter, I knew that I was back to trouble again.
BTW, this came on so gradually in just the last 50 miles, again. Same symptoms as last time.
So we don't think that there could be a clogged oil passage?
I think that parts from the recent repair are still around. If I find them, I will send a pic.

 

PS:
RE: Colorodo Springs
We were supposed to drive out to Colorado Springs (Broadmoor) in the P-Car this Spring for an event. For obvious reasons, that never happened!
Maybe we'll see you next year..

 

So if this means your guy used new GM lifter trays during the last repair, then that should be good.

 

He used Comp Cam lifters and push rods.

Here is a picture:

 

I'd look at spring seat/open pressure, pushrod length, and lastly where coil binding occurs in relation to your cam lift. That lifter doesn't appear to have turned. It looks more like the lifters aren't overcoming spring pressure so I'd look at coil bind and pushrod length first. What exact springs were used? What pushrods were used? 7.8? 7.825? What model spring so I can look up the coil bind and pressures. What was the cam lift for the lifter that failed? The LS7 uses 1.8 rockers so it increases lift as seen by the lifter. Do you have the cam card?

Edit: LS7 rods are longer 7.8 ect

 

Scootguy, your picture shows a classic example of the result of a roller lifter that can turn back and forth when running. When the lifter turns one way, the edge of the roller contacts the cam surface and skids a little instead of rolling true because it is now out of alignment. Then when the lifter turns the other way, the same thing happens at the other edge of the roller. This causes the edges of the roller to chip, and skid marks appear on the surface of the cam, just as in your picture. It is unmistakable. In order to fix your engine, you need to find out what allowed the lifter to turn, and fix it. The original GM lifter trays hold the lifter in alignment, but can wear out at some point and allow the lifter to turn. Some aftermarket lifter trays are poorly designed and built such that they allow the lifter to turn even when new. I could be wrong, but here is my best judgement as to what happened in your case:

Your lifters and cam failed at 84,000 miles because the original GM lifter tray was worn out and allowed one or more of the lifters to turn, which caused the type of damage shown in your photo. During repair, your guy either installed the original, worn GM lifter trays, or installed new aftermarket lifter trays of poor quality from Autozone or O'Reily, etc. The only known good lifter trays to use are the GM parts sold by the GM parts department. So then, after a new cam and lifters were installed along with defective lifter trays, the same failure occurred again in short order. I hope you get it working as it should be. Here is a video about this problem that I think you will find interesting:

 

Beautiful!!
That surely could be it, I will be visiting with my guy later today and will report back on whether he changed the trays and if so ,GM or knockoff. Thanks for the lesson.

 

COMP 8905-16
CS Hi-Tech 3/8 STD 7.75
Is that enough numbers for ya'?
PS: This is not my Guy's first rodeo and I have been using him for diagnosis and repair for eight or nine years. We are just trying to get to the bottom of the problem. Thank you all for your help and suggestions. Somewhere in there is the nugget we need to mine.

 

Spin...
LS-1 277LrR HR-113
Grind# LS-1 277LrR HR 113
Gross valve lift Int .613 Ex. .623

Does that help?

 

replace the lifter tray if not done already

 

Like Spin mentioned, your actual valve lift is .650 on the intake and .661 on the exhaust. The gross valve lift on the cam card or cam description is figured with 1.7 ratio rockers. A Z06 has 1.8's. Was your bad lifter on an exhaust valve? That might point a little more towards coil bind.

 

Do GM lifter trays have specific markings on them? Do they have a part number or say GM. I recently bought some from FleaBay and they were touted as OEM GM lifters trays. I can't see any indication that they are GMs however. They are very tight on the new lifters however.

 

I don't need any numbers. People are simply trying to help you and you are being asked for the required info to determine if the parts used contributed to the failure (twice). You came on a forum asking for input then you say your guy has been in a few rodeos. If he has it all under control, why ask here? No one is taking shots at anyone. We are only trying to help.
The model spring must be far enough away from coil bind @.660 if the lift in your LS7 using this cam is .661 for the exhaust side. I'll ask again, what model spring was used?

Edit: the flip side to that is if the spring has too much seat pressure it is pushing down too hard on the plunger effectively making the engine a solid roller motor upon start-up especially after sitting for a while.