MTIRC6Z

You're forgiven

Fortunately I don't need to ask for your forgiveness since I did read your entire post

While we are analysing motives, I should mention that I have no horse in this race. I still have stock valves and thus it does not matter one tiny bit to me what has, or has not, happened to the OP's valves after a grand total of 8,000 miles...though I'll admit I'm sure my feelings about this would differ considerably IF I was running valves which testing has shown WILL bounce. This unfortunately is the price I pay for believing in the laws of physics

Just imagine how good SS valve users would feel if the OP had posted that even after 88,000 of abuse in totally out of spec guides he was able to clean all the built-up coking from his exhaust valves, stick them back in the engine and then after another 20,000 miles be able to report they were still in perfect working order. Unfortunately such a report only exists for stock exhaust valves but hopefully the same will eventually be reported for SS valves because it is my hope that one day all SS valve users can truly have the same confidence in their choice of exhaust valves as those of us using stock exhaust valves

Cheers, Paul.

http://forums.corvetteforum.com/c6-z...-mortem-3.html

propain

You must not be on one of those pesky phones that cant read 2 paragraph posts but can write 6 paragraph posts. One day I hope the technology improves so we can actually read and write posts at the same time.

'06 Quicksilver Z06

You know Paul, I don't worry about it either.

Predictions of calamity, and when widespread calamity still has not struck, don't mean much to me.

But the fact still remains, had this gone "the other way", and the guy had said that his shop found his exhaust valves to be shot due to "valve bounce", then there would be those who would be pointing right now to it confirming some of the predictions made which apparently have not come about.

As it stands, his builder says; "I saw no signs of valve bounce".

I'm glad to see, that despite all of that testing, and some of this and that predicting, this guy's car managed to go 3 years and 8k miles "in the field", and his builder comes back and says after tearing down and examining his heads, "I saw no signs of valve bounce".

Found worn guides, mind you, but says that he "saw no signs of valve bounce"

The other good thing, is that posts can be edited, and additions made to them, even on an iPhone.

What will they think of next Paul?

Mark2009

You're discussing other people instead of discussing the issue.

You're discussing other people instead of discussing the issue.

You're discussing other people instead of discussing the issue.

You're discussing other people instead of discussing the issue.

You're discussing other people instead of discussing the issue.

While you've described your posting style perfectly, you're still discussing other people instead of discussing the issue.

And all of that from only one post

'06 Quicksilver Z06

And just where are you "discussing the issue" in that above rant?

Mark2009

Discussing other people instead of discussing the issue.

You've stated the obvious and the known twice now. We know what was posted. Apparently you think it is definitive, somehow, to the extent that repetition makes some kind of point, so... What do you think it means?

1. That there was no valve bounce in this engine.

2. That there is no such thing as valve bounce.

3. That there is valve bounce, but it doesn't mean anything.

Bonus question: Do you think the naked eye is sufficient for metallurgical testing and analysis? i.e., if you can't see it with the naked eye, then it doesn't exist?

JCox23

After going through my reciepts I didn't see anything that said what brand of dual springs were installed. I'll have to do some more digging.

Mark2009

It would be difficult to discern anything unless you had the model number and the installed height... that would be the only way to determine the actual spring pressures in use.

It's only recently come to light (AFAIK), thanks to the Spintron testing that Katech so generously published here, that a beehive can do just as good a job as a dual with some of the heavier valves. Prior to that I think just about everyone figured a dual was needed for the LS7 RPM and a 100g valve.

If you car hasn't spent any time above 6500 RPM then it is pretty much a moot point... most springs seem to be capable with the heavier exhaust valve up to that point.

BTW, your video showed ~.022 wiggle, and estimating the measurement point at 3" from the valve guide I'd put your actual guide clearance at .022/4 = .0055
.

'06 Quicksilver Z06

Yes, but have you gotten it yet? Or do I need to say it a third time? :

Here it is one more time.

The "issue" is that JCox23 has discovered guide wear, but has no evidence, none whatsoever, of "valve bounce" despite the fact that his is a heavier than stock valve train.

Why do you want to know what I think that it means?

It only matters what the grass roots member in here, attempting to avoid a windowed engine block, and deciding upon which steps to achieve that end, thinks that it means.

Why don't you post up a thread asking them what they think it means?

Do you think that metallurgical testing and analysis is necessary and practical for determining say, the current structural integrity of your wheels, or your brake calipers?

Or do you think that your naked eye is sufficient for you to keep driving on both?

If so, well then why?

If not, well then why not?

Is that out of spec?

Because if it is, and I do believe that it is, well then JCox23 is lucky that he got those guides out of his car when he did.

propain

Its the model and install height I am looking for or hoping for.

and this is why testing and data is so important. Yes experience goes a long way but sadly not in this case as the Beehive spring is far superior to the dual spring in the cammed scenario. The tradeoff in bounce verse the security of the dual spring is not worth it in my opinion.

Agreed. I think most buy these type of cars to get what they were intended to run. Not gimp the throttle so we don't do damage or fear doing damage.

Mark2009

I figured you'd avoid stating your opinion on valve bounce. Fair enough

Personally I believe it is real, and that it can happen without being seen/felt/heard/tasted by the operator/mechanic (extreme levels would likely be noticeable on a load cell dyno), and that even at moderate levels it can lead to overstressing of various components resulting in cumulative unseen damage up to and including failure.

If they have been subjected to some type of unusual abuse or stress, absolutely. That's the only way to tell if the original structural integrity has been compromised. A wheel stud looks just fine until it breaks off... and it probably doesn't break the first time it is overtorqued....

Mark2009

propain

OMG....

'06 Quicksilver Z06

Damn, you make it sound so "technical" it's a miracle that some of these brick and mortar outfits offering their services on our forum, but without every piece of fancy equipment have been able to successfully make it this far, and last for this long.

One wonders how they've managed.

I read the above again, and it almost sounds like you're describing carbon monoxide poisoning or repeated exposure to low dose radiation. Hell, it even sounds like "radiation", when you go on about "extreme levels" and such. Of course we know those can cause dire consequences, even kill, and can point to examples of morbidity and mortality associated with each.

I guess all we have to do now, is wait for you to show us several confirmed examples of LS7 engines with "fixed heads" failing, or demonstrating ….what was it you called it…."unseen damage", as a result of what you describe above.

I'm ready when you are.

I didn't say "unusual abuse or stress", I said "Do you think that metallurgical testing and analysis is necessary and practical for determining say, the current structural integrity of your wheels, or your brake calipers?

Or do you think that your naked eye is sufficient for you to keep driving on both?"

Did you buy your car new or used?

Because if it wasn't bought new, then how would you know that your wheels had or had not been subjected to any "unusual abuse or stress"?

I laughed at that too, because it has such broad application.

csumt76

I could have made that video last week with a 6,000 mile set of Germany's finest. Oh, pull the valve half way out of the guide and it wiggles under no load. Interesting.

MTIRC6Z

Certainly .0055" is out of spec but it not nearly as far out of spec as a boat load of other examples in the .0120+ range (including ironically two sets you've personally had your hands on) which did NOT blow up. So in fact there are a boat load of examples indicating that .0055" is no where near a catastrophic failure, particularly when were talking about stock exhaust valves which have frequently survived in guides which are THREE times worse than was measured by the OP.

When it comes to SS exhaust valves I believe the OP's is one of the first examples where the valve did not fail with out of spec guides but given the guides were not vastly out of spec they have not had to withstand nearly the amount of abuse many stock valves have.

Please note in this post that I am discussing valves and guides (ie. the topic at issue) and NOT people.

Cheers, Paul.

z51vett

Yes I was wondering the same thing valve was pulled almost out of the head to check movement not giving a correct reading.
z51vett
Doug

'06 Quicksilver Z06

What two sets of heads are you talking about?

You clearly have me confused with someone else, so perhaps while you claim to not be talking about "people", perhaps you should have taken the time to determine which person in here has in fact had his hands on two sets of heads with guides in them worn to .0120".

Wasn't me.

Do yourself a favor and don't follow your buddy into the "talking about people" flames and rips. Look at where it got you. You were doing fine. We were having a clean and civil discussion between us. Don't go down his road.

You think these "valves and guides" you say that you're discussing, got into these cars with no decisional input from "people"?

The "people" , especially those whom I refer to sometimes in here as the "grass roots segment" of this forum, who may not have a big budget to spend replacing an engine that just grew a window into the side of it's block, e.g. the guy in here still making a car payment, or paying tuition for 2 kids in college, or has other economic considerations, and is just barely able to hold on to his Z06 in these tough economic times, have to decide what they are going to do about this matter.

You talk to those people about better than $2300.00 worth of new titanium exhaust and intake valves, as a potential avenue for addressing this matter, and that is just too far out of their reach. That kind of money for just valves alone, is possibly going to be a tough nut to crack for the guy making a monthly payment, and insurance. He may not have it. But he still wants to protect himself and he deserves to know his options and hear those options discussed, pro and con, and that includes any consumer perspective and evaluation of vendor claims.

You try and tell them the stock valves are fine, they aren't buying that either when they continue to see them fail in here.

Their observations of what has thus far gone on with this issue, and the discussions in here about it, have an influence on what those "people" ultimate do about it.

It's that segment of "people", our fellow forum members, who I direct many of my comments toward.

So yes, I am concerned about some of the "people" amongst our forum membership still trying to decide what to do about this matter.

And they are concerned and watching closely, and we see what the trend in here is. Were what they were doing not working, well then it is doubtful that this would be the case.

The second part above in bold "qualified" with the phrase "one of the first", well, really in here, one cannot show very many examples in here of SS valves failing at all, once you get past the Madsen case. A case where he was still using the stock guides, which went so severely out of spec that TJ Wong elected not to measure them.

MTIRC6Z

Okay so I must be mistaken because I was sure the heads you pulled from your car had at least a few guides in the .0120+ range and it hadn't blown up before you pulled them...I apologise IF my memory has failed me.

And the used heads you bought to 'fix' before you pulled yours were measure by WCCH to also have some guides worse than .0120" and they too had not blown up before you bought them...but again I seem to be mistaken and apologise. Both these pairs of heads had stock valves and would have have passed through your hands but apparently were not as badly worn as I thought...my bad.

BTW, I am talking about 'your' heads, guides and valves here NOT about YOU personally...a world of difference there buddy so why have you suddenly become so hostile???

Again you seem to be completely misunderstanding my point. I was NOT talking about valve failures I was talking about valves that have NOT failed while living in a VERY hostile environment (ie. guides with more than .0120" clearance). This is what we have many examples of when it comes to stock exhaust valves but very few, if any, examples of when it comes to SS valves. Seems to me to be a very relevant point of discussion since we do have proof that using SS valves does not guarantee a lack of guide wear.

Cheers, Paul.

'06 Quicksilver Z06

No. Perhaps you have me confused with someone else.

Yes. The gentleman I sold them to, had them measured locally.

He sent me a copy of the measurements which they had obtained.

This was at 20K miles, and the car had Mobil 1 5w30 run in it for most of it's life, until switching to Renewable Lubricants, BioSynExtra 10W30 at about 18K miles.

At any rate, this is the valve guide wear found in my heads at 20,061 miles.

Position "C" is at the base of the guide or the combustion chamber side of the guide, position "B" the center, Position "A" the valve spring side.

The worst were in the 0.004x range.

The other exhaust valve guides were right on the verge of going out of spec at 0.0035"-0.0036" at just 20K miles. The service limit, for those interested, is 0.0037".



See above.

Also, the sheet showing the clearances of my spare heads is below.

http://forums.corvetteforum.com/1581764436-post20.html


Those heads had one exhaust guide above that .0120" number which you mention above.

No hostility intended. Sorry if it came across as such.

Again, though with regard to my heads, the spec sheets are posted above.

So the statement; is not accurate. The only set of heads which I have owned with any guide above 0.0120" was my set of spare heads.

I understand.

In actuality, the original poster of this thread, and blackc6z, posted in another thread started by a troy6166, who had his car done by the same shop, and he reported severe stock guide wear as well.

He reported no valve failure.

I wonder if anything can guarantee a lack of guide wear.

Are guides a "wear item"?

It would seem to me that they would be.

How long can guides go before they wear out?