'06 Quicksilver Z06

As many of you already know, after many debates, I bought a spare set of cylinder heads and sent them to WCCH for their Stage 2 package.

I did this in response to the many discussions on the LS7 valve matter, and after doing a great deal of research, becoming concerned that my own heads might be at risk, and that warranty might not cover me in the event of a major mishap.

I sold my heads to a local forum member and that forum member decided to have the valve guide tolerances checked locally here in the Western PA area.

This is important, because there has been talk, that every set of heads that Richard at WCCH gets, somehow has valve guides which are out of spec. This talk, I can't help but wonder if, it is intended to imply that Richard is fudging the numbers that he states when he documents valve guide wear, in order to make this matter of LS7 valve guide wear into more of an issue than what it actually is and to profit from it.

Well, whatever is the case, these heads, were not sent to Richard. These were measured here locally. Guides were found to be out of spec, in a set of 20K mile heads, by someone else other than Richard.

The gentleman who bought my heads, I cannot say enough good things about him. He asked me to post up this information below on the valve guide measurements in the heads which he bought from me.

If you recall, I showed an image of my odometer taken the day that my car was dropped off for the install of the heads done by WCCH.



The car has had Mobil 1 5w30 run in it for most of it's life, until switching to Renewable Lubricants, BioSynExtra 10W30 about 1 year and around 2K miles ago.

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.



Using the information posted by Hoefi, 3 of the exhaust valve guides are out of spec at .0040", .0042" and .0040"

Considering that .0037" is the max, 4 more of my exhaust valves, were right at the borderline measuring in at .0035" and having about .0002" to go before reaching the service limit. I am certain that I would have made it to 2/10,000ths of an inch in a short period.

All of the intake guides are within spec.

kenw

OK Quick for those who don't know how to read that is the wear alot or a little.

'06 Quicksilver Z06

The service limit is .0037". So any number you see above .0037" is out of the service limit.

At approximately 20K miles, 3 of my exhaust valves were already out of spec, or out of the service limit, and 4 more were headed there, measuring out at .0035" having just .0002" to go before they too would reach the service limit.

So to answer your question, at 20K miles to have 3 of my 8 exhaust valve guides already out of spec, is concerning.

Do know that I had no clue that they were before I proceeded with having my spare set of heads done.

And also people have asked me; "Hey Quick, what if you find out that your heads were alright all along, and you jumped the gun sending that set of heads to WCCH and pulling your own."

Well, at 20,061 miles and already 3 of my exhaust valve guides are already out of spec, and 4 more are headed there, is unacceptable.

The money I spent on that spare set of heads is looking better and better each day.

Mopar Jimmy

Thanks for posting up the info Quick, very interesting and of course also concerning on a stock Z with only 20K miles on it.

I wonder how long your engine would have lived had you done nothing?

30K, 40K, 50K, 70K, 80K, 90K, 100K+ miles?

Nobody can answer that but that is always an interesting thought.

GOOD Luck with your new set-up I think you will be very happy over the long haul.

It will be interesting to see what the WCCH heads look like after 20,000 miles, that will be the big test as more and more of the WCCH heads get miles on them.

SSSUPRA

Definitely better to just go ahead and get it out of the way if you have the means. That sucks to see some of them out of spec at such low miles.

'06 Quicksilver Z06

It would have taken a $15K-$17K plus labor wager to have found out Jimmy.

And my luck has been running terrible lately.


Yes. Yes it is. For somebody.

I can tell you though that the gentleman who bought those heads from me, is probably not going to bolt them directly to his car AS IS.

In fact, I don't think that anybody would. They need work.

He is going to have the heads worked too. How, I don't know exactly yet.

Jimmy, my man, I am happy over the SHORT haul. We won't even talk about how happy I'll be over the long haul. I can't stop driving this bad boy, in fact, I have the itch to drive it right now, but I'm in here with you.

There is a lot to be said for being able to drive your car as hard as you want to and knowing that it is not going to drop a valve.

I did some 60-100mph runs yesterday dialing this tune in, and will be doing some WOT stuff in the near future at the track to get that part of the tune nailed down.

Yes, it will. But there are a few more in the line ahead of me. There are cars out there with 5 digit miles on them running heads set up like these, so, I'll continue to observe.

3LZZ06

Quick, according to the data you have there, your heads were probably going to last a very long time, well over 100,000 miles IMO.

The (3) guides that were out of service tolerance were only out by .0003-.0005, and that was only on the combustion end of the guide bore (slightly bell-mouthed), with the remaining 2/3rds of those (3) guide bores being well within specs. "Excellent measurements for new valve guides, never mind heads with 20K on them"

For those that aren't familiar with what the measurement of .0003 equates to in laymens terms, it's 1/10th of a human hair.

I'd just change the springs on those since they're out of the car anyway and call it a day for at least the next 30K mile checkup (or more) .

The problem heads are much further out than yours were, 20 to 30 times further out...now that's sloppy and worth worrying about.

VicCaerter

Kind of interesting that the measurements indicate a somewhat bell shape to the guide.

Do you know if the valves themselves were measured individually per guide?

'06 Quicksilver Z06

Part of my point here though 3LZ, is that it only took 20K miles to get to that point where three were already out of spec, and 4 more were just .0002 away from being at the service limit.

No offense here 3LZ, but out of spec, is out of spec. No way in hell, that if I myself were buying these heads that I would just change the springs on them and bolt them onto my car and sleep well at night out of warranty, knowing that I would be beating on the car at the track and on the street..

But now that's just me. Other folks might feel comfortable doing that. I wouldn't.

OJCrush08

Wow. I think this is yet another definitive piece of information illustrating that this is a more common problem than most of us would like to admit, and until recently, we were unwilling to confront.

I am not sure we will ever get a definitive answer as to why this is occurring with an unacceptable level of frequency. Over just the past several weeks I have met two Z06 owners (one now a GS owner) who have had these valve failures in their Z's as diagnosed by the dealership. Both cars out of warranty. Both gentlemen are not members of the Forum, in fact, never heard of it.

I relayed what I understand about this valve issue to an old school buddy of mine who graduated from Lehigh University (a well respected engineering school in PA, my home state). He has an advanced degree in metallurgy and works at Oak Ridge specializing in something to do with surface interactions, wear physics or whatever! He suggested that MAYBE these failure percentages are caused by a complex interaction of a variety of materials that in the occasion of a failure, are just not produced closely enough within a tight enough small window of acceptable tolerances, perhaps because the Q/C parameters were not specified within tight enough allowances, therefore production variances deemed acceptable, should be reevaluated. Or at least I think that is what he was trying to say!

Anyway, whatever the reason(s), I doubt we will hear much from GM, it's on us, as the owners to decide which course of action is best for us.

Quick, major kudos (again) to you for your diligence in pursuing this issue and remaining open-minde enough to let facts, rather then emotions and rhetoric, guide your actions.

All too rare here, thus, highly valued.

Thank you. Now, I need to do some serious thinking. I have time, my '10 has an in-service date of 08/11 and has about 3300 miles on it. Already running the Mobil Euro 0-14 oil.

Mopar Jimmy

Quick,

You excitement and enthusiasm for your new heads/cam C6 Z is jumping off your posts here.

I know that awesome feeling your experiencing (been there) and I'm happy for you my friend!!

'06 Quicksilver Z06

Well, don't thank me, the actual credit goes to the gentleman who bought the heads from me.

He is one of our own, a forum member, who prefers to remain for the most part silent in these threads.

When he initially purchased the heads from me, sight unseen, and still on my car, he told me what his intentions were.

That is, he intended all along to have the guides measured in these heads to determine the degree of wear.

I believe that his plan now is to use these as a spare set of heads.

BigMike NY

Quick, I understand your using 20K miles as your point of concern. It should be argued that 20K miles under your right foot may not be the same as 20K miles from someone else. Mileage is subjective to driver and conditions.

3LZZ06

Keep in mind Quick, the measurements taken may be very close to break-in dimensions of the guides. They will all wear just like cylinder bores will, but the wear will slow down after break-in.

I've been involved in machining for many years and I can promise you that when it comes to measuring .0001, .0002 or .0003 of an inch, it amounts to absolutely minimal material.

Again .0003 equates to 1/10th of a human hair. The problem heads have more like 20-30 times that slop...I wouldn't worry in the least with your findings, in fact I would be pleased.

Maybe others with machining experience may chime in here...

One more thing to consider is that measuring close tolerances can vary from person to person up to .0002 even with a highly skilled craftsman doing the measuring, so where you heads were at, certainly is not concerning in any way...drag strip or street.

Also, I would only change the springs because the heads are apart, not necessarily because they need them.

Dan Parker '96

Honestly, I don't understand what you expect out of these results. Wouldn't most people just run these engines until they sell the car or a failure happens? The factory warranty is VERY long for this application (I have taken advantage of it myself) and is factory extendable for 48 months (again I've taken advantage). Basically, this engine can be warrantied for 9 years for ~$2100 bucks. Run the **** out of it.

'06 Quicksilver Z06

I thought about the variability of one person's obtained measurements vs those of another.

You make a good point.

Gary '09 C6

a cost-effective alternative that may be less worrisome to some...if available to them.

'06 Quicksilver Z06

Interesting perspective.

If you don't mind my asking, what would you recommend for those who didn't or couldn't extend it, as the 2006 models only had 3yr warranties? :

And BTW, don't you have to make the decision to extend the warranty all of those years before the 3yr bumper to bumper runs out, or in other words, within 36 months?

OJCrush08

I get what you are saying. What I do not get is why there are growing reports of failures atttributed to dropped valves, if there is no at least occasionally occuring systemic problem. Although people who buy Z06's tend to drive them more aggressively, I don't think all of the stock failures or reports of excessive wear are the results of incompetent drivers, abuse, and/or inadequate maintenance. Do you? Really? I don't, not anymore.

Perhaps, sometimes in Life, what appears obvious, should be accepted as such.

oicw

Has anyone measured a set of SS valve / bronze guide combo after accumulating a considerable amount of miles?

Basically, as a new 06 owner (so long out of warranty), I'd like to know if the SS / bronze approach is a fix, or simply another bandaid that lasts 30k miles before being out of spec again.