SRVfan09

Bill Dearborn

It would be nice but there is no way to guarantee the consistency of data collection with things scattered across a couple of countries and different people using different methods to document things plus some measurements will cost money and who will pay the bill? For instance you asked to see the measurements taken on a brand new head. Tanner has to use what he has on hand and I don't think he will purchase a brand new head and a set of valves from GM just to provide a baseline. I know I wouldn't unless I had some way to sell the parts for what I had in them once I was done. Then there is the issue of paying all of the professionals who would be doing the measuring. Time is money for them and I don't see them spending the effort to set up to collect the data and keep it straight and also spending the time to make all of the redundant measurements required to build a comprehensive data base. You only get so much work when everybody is a volunteer that also has to put food on the table by doing their day job.

Since you are a manager you also know that in business just like the military you have to make a decision on the data that is available when it is time to make the decision. I have a new engine courtesy of GM but I know there hasn't been a change in LS7 part numbers from 2005 through 2011 (part number of the new LS7 built in May of last year was the same as the original engine which was installed in the car in Dec.07) which means there have been no changes. So how long do I wait to have the heads inspected and what do I do if there is an issue with them? Do I take the car to the dealer and pay to have their mechanic make the measurements and if there is a potential problem try and get GM to fix it even though the engine hasn't broken yet? Do I wait and see if it pops and then see about getting it fixed under warranty or GMPP? Do I take it to a respectable shop and have them do a preemptive replacement of the guides and valves? I don't want to modify the engine since it is just fine without mods so it might not be all that expensive to have done.

It is just like when the doctor tells you you have Prostate Cancer and your choices are watchful waiting, surgery or radiation treatment but they will not make any recommendations on which one to do other than the normal platitudes. Watchful waiting may work just fine or it may not, surgery may work or it may not, radiation may work or it may not. Here is a book read up on it and come back and tell me what you want to do. At least the dropped valve issue isn't as scary.

Bill

ZeeOSix

Yes indeed ... the 2002~2003 LS6 does have the valve spring failure issue ... but no loose valve guide problems that I've ever heard of.

Sounds like the LS7 has it's own gremlin with these worn out guides ... too bad, as nobody wants to deal with possible major engine destruction due to a design flaw or poor quality control on parts, etc.

SRVfan09

Once again, I agree, just trying to point out what may help the guys like LS7 BUD and others when posting up about failures. At the least it would be nice to know the engine build dates for those that have failed. Ended up going down a bit of a rabbit hole there.

Oh, and for what it is worth...

My Z is an 09 with 29000 miles and is my daily driver. I've got 1.5 years of powertrain left and won't do an HDPE until that is up. I am also not going to do an HDPE until I have headwork done. I planned that even before these threads started, I figured 2K is worth the beefed up top end and good insurance toward not blowing the motor. The plan is to turn it into a track queen once paid off in a few years.

'06 Quicksilver Z06

I certainly agree with your last couple of posts, and can also relate to taking a logical and analytical approach to this matter.

What you describe in your posts would be effective. But lets face it, what you describe is also ambitious.

We are only talking about a matter which concerns about 27,000 cars. Not all of those cars are going to be affected, and all of them built with planned obsolescence .

In short, we can find out that which we want to know utilizing methods you outline above. But at what overall cost in terms of effort and money vs benefit?

In short, what you are describing, is an expensive endeavor, in terms of time and money, for whichever professional embarks on it.

Finally, his return on his investment, because we are talking about an entity designed with obsolescence in mind, is likely to be nil, or just slightly above it.


This matter pretty much boils down to risk assessment and risk management.

The first order of business for any owner, and this is the reason why these non owners need to butt out of these discussions, is to access one's risk.

Is you car modded? Does it see a lot of track duty?

But the risk assessment step of it, is typically where it gets twisted. There are those who make unsubstantiated claims that risk is high, no matter what.

These unsubstantiated claims that the risk is extreme, are what drive a lot of the steps taken towards management of the risk.

I have looked over what data we have and determined that I am at minimal risk, and thus I don't worry about it.

SRVfan09

Yes, very ambitious and probably not feasible (I realize I was being a bit idealistic). But then again, they (tanner/LS7 Bud) did take the time to make several videos about it. My initial point was meant to be this:

Those who post about failure should include as much data as possible which in turn will help to educate and probably deter some of the "attack" as they describe it. I see the "attack" as being those with curious/skeptical minds wanting more substance behind the failure.

'06 Quicksilver Z06

Because this matter cuts across model years, engine build dates, while something I considered, could help, for example if a given supplier was being used during one , two or more different sets of build dates, and problems tended to show up whenever that supplier was involved, but build dates could also end up being useless.

However engine build dates do have the potential to be quite valuable.

Perhaps a more valuable tool would be cylinder head manufacturing date.

Of course even with that knowledge, because the matter has cut across model years, it may not be as effective.

Of course none of this makes a difference to you if you believe in the "design flaw" theory. Perhaps the most flimsy theory out there with regard to this matter as if a "design flaw" truly existed, then considerably more instances of stock failure would be discussed here.

Which brings us to another point, the notion that stock failure is rampant, and the tendency to state that it is with no real proof that it is.

SmokinZ

Hi guys,

Update... Took the valve cover off, looks pretty clean. Retainers, clips, bearings, valve springs, seal springs all look good. There is very obvious guide wear though, see the linked youtube video. I filmed the stem movement while all assembled, this was the exhaust on my #3 cylinder. I believe it to be the bad valve. I had also filmed the significant movement on #5 exhaust to compare, but my camera battery died, I'll have to charge it and retry. (This is all "on engine", only valve cover off)

Edit: Also while doing this I think you can do a check like I show here if you are worried. It wont be real accurate, micrometer accurate, but if it is as bad as mine, you will know. I didn't even have to relieve any valve train pressure to check the other valves.

The orange tinge is from my drop light.

'06 Quicksilver Z06

yes, I agree with you.

The problem arises when the data is scrutinized and those presenting the data, become offended when it is scrutinized.

I said this to Bud earlier, don't offer up data in a presentation, if you are too thin skinned to have it dissected.

This is what is foreign to me, when I was in training, if you presented something before your peers, and superiors, you could almost expect it to get ripped apart.

And you had better be able to defend your position.....with facts, and not bull$#!*, which seems to be just about the standard, or the threshold in here.

Just unsubstantiated bull s***.

And then people get pissed when they get called on it. Say that you are picking on them.

You have seen it in here, perhaps in this thread. An outlandish claim is made and then the person making the claim challenges those in the audience to "prove him wrong".

Guy in here just a few days ago, made some completely off the wall claim about there being more than 280 instances of stock LS7 failure, and said that he must be right, because no one could prove him wrong.

No figures, no cases, no nothing....just pulled a number straight from out of his ***.

What a load of horse****.

But it's this sort of thing which is the accepted standard on this matter.

Mr. Gizmo

What does Katech say about this. On youtube there were a couple of other videos showing the slop in the LS7 valve guides.

Katech has had to have a bunch of these a part and would be interested to see what they have discovered

ZeeOSix

That valve guide is obviously toast.

Jasil

It's almost laughable at this point that people think there isn't a problem!!

AirBusPilot

Yep. He's not an engineer or machinist.

Kind of like I'd be considered an amateur airplane mechanic, even though I know how it works and have 10,000 hours flying one.

AirBusPilot

Posted at 19:37
http://forums.corvetteforum.com/1581405964-post208.html

How are you going to do that, didn't you just post earlier that the car in question was already at the dealer getting a new engine?

Posted at 19:06
http://forums.corvetteforum.com/1581405730-post194.html

What else are you lying about?

'06 Quicksilver Z06

Another misconception or a misstatement of the fact.

The actual bone of contention, at this stage of the discussion, is the actual magnitude of "a problem".

If only one car fails, then there is "a problem".

But the disagreement lies in how big of a "problem" we are looking at.

Some contend that it is huge, and they have no way of proving that it is.

jbs02somws6

Just bought my 09z a few months ago, so I'm somewhat "shy" about posting in these forums, especially these broken exhaust valve threads in particular. This is due to the extreme stances of some, but good grief have some of you guys even watched these videos?? It IS ridiculous that these valves have that much play being moved by hand. On the plus side these failure threads have been a great source of bad comedy.

LS7 BUD

We are gonna use my 06 & 08 heads to do the measurements... He didn't get a chance to use the 2010 heads... Now your accusing me of lying... Did I say we were gonna use the 2010 heads??!

AirBusPilot

Interesting analogy, the flat tire.

There are two camps arguing here.

One camp sees several flat tires and concludes:

1. Tires are defective and dangerous!

The other camps sees several flats and concludes:

1. Those particular tires were defective, but sees nothing to conclude that ALL tires are defective, and;

2. No one has provided any evidence of why certain tires have failed and others have not.

AirBusPilot

What's the title of this thread you started?

And, you've already stated that your brother has inspected your newly ported heads and admired the porting tanner did.

Are you saying you're going to mail back your heads to tanner, so he can make a 3 minute video? Where's he from again?

Beach Bum

Somebody should link that video over at speedtalk.com and see what some of those bonafide in-depth cylinder head experts think of that much valve play. I'm guessing they are going to say its extremely excessive, even without an indicator, but just visually that'll be enough to tell them the problem. If you also tell them its also an offset (60/40 valve spacing) cylinder head due to the massive 2.20" intake valve. (It has to be due to the fact standard valve placement cannot be achieved, they can probably diagnosis the problem. (Which more than likely, that is caused by geometry issues)

That type of extreme exhaust valve play due to guide wear is not new... its common on 23 degree aftermarket cylinder heads with a 2.10" valve or bigger that are set-up in-correctly. (Cylinder heads with 2.10" intake valve and bigger usually requires 60/40 valve spacing.... which I might add is a variance and just a term used for having to reposition the valves, meaning every cylinder head manufacturer will space differently. There is no definitive standard) Gotta have that geometry set-up perfectly on a car that is going to see some miles. I think the predominant reason for guide wear is just this problem on any motor, not just the LS7.

Not saying the LS7 inherently has this problem... just pointing out this has been seen before in the past, and they knew why. Its not new. But ask them.... you'll get an honest 100% completely un-biased answer from those guys.