I'm glad people are learning more of this issue from my blown engine.

When I get this block home, I'll take pics of the carnage and post it. I have never seen such a large hole in the block. Story was the owner was rippi g down the road at 120mph and it went boom. The extent of the damage was pretty big but my car is now back together and running 100%. Excited to pick it up next week.
Aj

Yes well I must say whilst I understand many believe SS and bronze fixes the problem, it is as yet unproven. It looks good but it is very early days still and even if it works the actual cause is unclear. And I do understand being sure is valid - ie IF longterm it does FIX it completely. BELIEVE it works ?? Maybe but only time will tell.

And just as unproven is that the fault is guides or valves or both or neither?

The only proof will be when those using original valves in bronze guides and SS valves in original guides can produce verifiable data. Then add in the longer term results of SS valves with bronze guides and then maybe the evidence will give some concrete proof of where the weakness is.

When some people can drive cars totally original for over 150K miles without incident, and others have bad wear after 5K miles, it is awfully hard to rationalise anything from current stats.

I can see the argument from both sides and nobody has proven anything conclusively. And I expect GM trying to prove the problem would be having similar difficulties with so many variables.

I think it was mentioned to take any learnings from a supplier in the business of selling valves with a grain of salt. Good advice.

This theory has some great points to it. Besides the size, I wonder how different the LS6 valve is from the LS7 in terms of how close the hollow stem is to the head.

We see garage queens with 9,000 miles that were never tracked having guides out of spec and then mine with over 100 drag passes (plenty of heat exposure) having guides in spec at more than double the mileage. These two examples certainly don't support the theory. Like many have said, likely there is no one single cause. This theory could apply to the heavily tracked cars more, and the mismachined guides could apply to the waxer cars being out of spec and or failing. Who knows. All I know is all cars running WCCH bronze guides have had 100% success with any valve, OEM hollow or SS.

[QUOTE=ConfusedGarage;1583783579]I think it was mentioned to take any learnings from a supplier in the business of selling valves with a grain of salt. Good advice.[quote]

Why?


Without a reader actually having to take the time to call Richard, what percentage, or better yet, what number of WCCH heads with these bronze guides in them, are running the OEM exhaust valves?

Also, most importantly, which valve does WCCH recommend for those wanting to address the LS7 valve train issue?

Once again......a most entertaining post. Please........don't stop now. :woohoo:

[QUOTE='06 Quicksilver Z06;1583783691][QUOTE=ConfusedGarage;1583783579]I think it was mentioned to take any learnings from a supplier in the business of selling valves with a grain of salt. Good advice.I guess the valve manufacturers have no interest in selling their valves and making money. Go to your local car dealer and see if they'd TRY to sell you a new car when your old vehicle is in perfect running condition.

I'd say roughly 200 of the 28,000+ LS7s have your SS setup to answer your question directly. Is that about correct? I don't know how many OEM valves are running with bronze, but I know they have the same success rate when done by Richard at WCCH. If you want to pick apart sample sizes, bronze OEM vs bronze SS are both WAY too small to be statistically significant.

It's like this. I say we've never seen an OEM valve fail, EVER, without having witnessed guide wear at the same time. My theory is the faulty guides (for whatever reason on some - just don't know) eventually fail the valve, and all the data I see supports this to me. If there was a higher number of valve failures than guide failures (I'll call any guide out of spec at time of measurement a failure because that's what it is) I'd be in the camp that the valve was defective. There isn't so the data says to me, that is just not true.

You say Z06_505 had a valve failure without guide wear. I contacted him and he told me word for word his car had guide wear but has no interest in e-battles with certain folks on this forum.

Most mature adults can delineate between a discussion and and an argument, and they also know which is more helpful. That's how things get accomplished effectively. Nobody has to agree on everything, but trying to verbally steamroll people that have a different perspective only benefits one person. The steamroller. We can question and discuss the data points and how they fit into the picture, but few care to battle back and forth arguing.

Irony: Clearly not a concept grasped by all :lol:

If WCCH had recommended new OEM valves to address the LS7 valve train issue, would you have followed their recommendation? http://i1114.photobucket.com/albums/...on_popcorn.gif

lets not forget.......I have a valve stem sitting on my desk with no signs of guide wear, yet it is still missing a head.

Mark,
What do your guides measure??

What causes the conditions leading to valve failure can be debated. It's fairly clear the guide is beating it up, but the "why this happens" can still be debated.

What cannot be debated is:
a) they stock valves fail
b) they break at the weld of the 2pc valve

Remove B and retest. So far so good!

That means you have the guide too? What are the ID's?

What's your own guides measure and what have you done about the one which you know is grossly out of spec besides talk?

But you know that all of the points you make, will be lost on some. Right?


They didn't. So no need for me to deal in that hypothetical.

Excellent rebuttal point counter point...Nothing is obvious nor is their a simplistic reason as to what is causing some to go bad early and some to not show much significant wear at least beyond the service limit with many miles on it..

Common sense would argue against a single part being the culprit.

The OEM valve is a generic part, they would have to be endowed with a diabolical personality to decide on which vehicle they will strike and which will go unaffected irrespective of mileage.

This is a complex engineering (sorry non engineers) problem whose solution is suited to complex analytical modeling supported by testing to verify modelling..All of which costs bushels of money and time.

Absent this, the recriminations and insulting the usual list of suspects will continue..

[QUOTE=ConfusedGarage;1583784048][QUOTE='06 Quicksilver Z06;1583783691]Very well stated sir!

Just because they manufacture and sell valves, doesn't mean that all they say about this should be taken "with a grain of salt".

There are still honest and ethical manufacturers out there. .

No. There are 220 that I have been able to find in here.

How many other owners outside of here, or even in here which I have not been able to identify, I don't know.

Also, not all 28,000 Z06 owners are in here.

So we don't know just how many have failed a stock exhaust valve.

Which is why I reply to your post in the manner which i did.

I merely asked you a few questions.

But if you want to believe that the only way one of these stock valves can snap a head off and fail, is if the guide it is in is grossly out of spec, and at a time when no one has the specs on all guides which had a valve fail inside of them, well then go ahead.

How far do your guides have to be out of spec for one to fail? Has anyone actually consistently shown just how far your guides have to be out of spec for one of the stock valves to snap off and window your block?

But go ahead. It's your wager.

But because there is arguably no practical benefit to making that wager, but instead considerable risk disproportionate to any benefit in making it, many of us choose not to make it.

But like I say, it's your car, so you're the one holding the dice.

I'm not one to tell you how to bet, but let me ask you, what do you "win" if you're right and what do you lose if you're wrong?

You feel lucky? ;). Anybody else?

I realize you are trying to stir the pot and state there is always going to be "some wear" because i chose my words poorly when i stated "no wear" but in comparison to the other valves i have seen there is a night and day difference. valves running in worn guides have a large tapering section of coked oil on them, ones that have a crisp line showing the seating position of the stem in the guide can be seen as performing under the design intent. Any motorcycle valves/car valves i have seen have displayed this when working properly.

I communicated with the person who had the heads and was reworking them. he stated the guides were all within spec at 24k of primarily tracked miles. It is impossible for us to know what valve was in what guide because the owner disassembled the heads himself. But i can tell you all but two of the valves had very crisp carbon lines on them, the broken one looked very clean as well. Nothing compared to what my valves looked like.

I sent an email to the guy with the heads to see if he still has the data, so fingers crossed.

Well if it is Z06_505's heads, then it is the same person's heads that Confused Garage says that he has communicated directly with and heard from him just the opposite.

I posted the spec sheet on those heads...they were all in spec

In case all of you were wondering what the engine looks like. This is the motor in discussion here. Came out of my 07 z06. Owner was supposedly tracking it and was at 120mph when it went


http://i1214.photobucket.com/albums/.../photo3-14.jpg

http://i1214.photobucket.com/albums/.../photo2-22.jpg

http://i1214.photobucket.com/albums/.../photo1-23.jpg