Griffee

Well if there is no data to support that this is "the cure", how can we construe it any other way? If bronze guides/stainless valves have a track record of lasting and holding up in a daily driven automobile with factory production like numbers...well then great...and I'm all on board. However is this just supposed to be the answer....well then I'll wait for others to test the waters first before diving in the pool.

'06 Quicksilver Z06

That approach has merit.

As does taking the plunge now if you feel the need to based on what we've seen thus far.

Beast5spdGTA

Quick,

What max oil temps during the 2 HPDEs? What type of oil during those events? Guestimate time above 6000 rpm over 20K miles (in hours)?

I know very little about the subject, but my gut feeling is a lot of the valve guide wear is related to temperatures and obviously engine use/abuse, which may be an oil type issue, geometry issue (angles and physical size), material issue or a mixture. Basically meaning that if you have never seen sustained (in hours) oil temps above 230+ F and the car doesn't burn oil or have bad valve seals, I wouldn't worry. Unmodified cars I'm talking about.

I know Mobile one 5W30 won't be my first choice for oil and the valve covers on my new(rebuilt) heads will be pulled after every 4 track days and/or 5000 miles assuming they aren't all highway. A simple valve wiggle test with rockers and springs installed will be performed.

'06 Quicksilver Z06

Mobil 1 5w30

Eight 20 minute sessions, I don't recall any oil temps above 230ºF

Bill Dearborn

The factory warranty is 5 years/100K miles and isn't extendable. If you buy a GMPP Service Plan before the 3/36 year base warranty runs out you can get a 7 year /56K service plan if you have less than 24K miles on the car. The service plan isn't a warranty and it isn't provided by GM but Ally which is a bank.

Bill

3LZZ06

1) As I mentioned earlier in the thread, I wouldn't touch anything in those heads except the springs, and only because they're already apart.

2) To have 3 guides worn .0003 of an inch out of spec on only 1/3 of the guide bore (2/3 of the bore being perfect) for a 20K mile car is spectacular!!!

3) It's hard convincing folks that .0003 is very difficult to measure because of how minute and insignificant it is, not to mention it would be pure luck for two skilled craftsman to read the exact same dimensions within .0002-.0003 of an inch.

4) Now if they were out .0030 or .0300, which many of the problem heads have been, the wear would be obvious to anyone using a micrometer and would necessitate a fix, but .0003 for three guides?...absolutely not

5) I'm sure the person measuring is completely qualified, but given how close those guides are to spec you could give those to another qualified person, and they would all be fine and dandy...rightfully so.

I would absolutely bet on it!!!...

gatti-man

Great plan unless you are out of warranty or modified. That's what I am doing as well.

'06 Quicksilver Z06

The thing that is bothersome here, is that I'm seeing:

.0040
.0042
.0035
.0040

....

.0035
.0035
.0035
.0030


Now .0037 is the service limit.

Three were measured out of the service limit, and 4 were measured almost right at it.

So if the argument is made that it would be pure luck for two skilled craftsman to read the exact same dimensions within .0002-.0003 of an inch, then that knife cuts both ways.

In other words, those which were measured out at .0035 by this company, may well have measured out to .0038 by someone else, and .0033 by the next guy.

And conversely, those which this company measured out to .0042, may well be measured out to .0045 by the next guy and .0039 by someone else.

So the troubling thing is that this company found 3 out of spec, and 4 more close to the limit at only 20,000 miles.

So even if the red measurements are "correct, give or take .0002"-.0003", then all three of those guides, are either right at the service limit, or still out of spec. in a car with 20K miles on it.

Unacceptable.

But if mine were "spectacular" then what are his below?? :

Dan Parker '96

Mine is a GM Major Guard plan (gmprotectionplan.com). I bought this with less than six months left on the 5/100. Warranty or service plan....makes no difference to me. Drivetrain is covered for the next 48 months.

But in regards to the original post, it is better that we pin down a mechanical weak point with the LS7 engine ( if there is one) so owners can be aware. Personally, if there is a potential fault I can check for later in life then that would be nice. Go to it gentlemen.

Random84

Agreed on being past the labels, I was commenting more on his reversal of demeanor and post content (all personal revelations aside).

A few months ago he was the List Maker - a voice of calm, reserved curiosity. Now... It's all "put your money where your mouth is" and making $17,000 wagers, etc.

I'm not saying I even disagree with his viewpoint given his findings.. Just that the change in perspective is rather contrasting (and interesting). Sorry to sidetrack, but his comment about gloating struck me as out of place, since that would more likely have come from all the people in favor of head work that he's argued with.... For years! Ha.

FWIW, I'm not sure I'd do anything differently in his position since were all obviously concerned.

Random84

Before we can comment on guide wear - we really need to know where these guides were coming in at on assembly. We also need to know what the tolerances of manufacture were: what's the range of acceptable ID on casting, 0.001 to .002?

What diameter are most made to?

'06 Quicksilver Z06

I could continue along the earlier path you point out, but:

1. It would get expensive.

2. It would be disingenuous were I to say one thing in here, and do entirely another in my own car and outside of here in order to "save face" and "hold the line to the end" so as to avoid a perceived "reversal of demeanor and past content", knowing what I now know in conversations which have come well outside of this forum.

I really don't care who perceives it as such, because this is my money that is on the line should things go bad. Not yours.

Since you won't be covering my expenses should the worst happen, I think I'll take the road that I am taking and let others know, that during the time frame that I was keeping that list you refer to, and getting calls and emails outside of this forum which you aren't privy to, talking to people locally and nationally, I saw something which let me know that there was more to this than what originally met the eye.



BTW, are you still waiting on GM's announcement?

Yes, typically when you get information about failures in here amongst active members, some of them quite prominent and who don't report them, it does indeed change your perspective.

One of the "benefits", or perhaps I should say it was a "curse", associated with running that list, is that it resulted in contact from several people in here who had themselves suffered failures that went unreported for a variety of reasons.

That list, was like dropping a firecracker down a manhole cover. I never expected in my wildest dreams to get the reaction from it that I did. Things that you didn't see. So while you see the names on that list of forum members..........it is the names of forum members that are absent from that list which would knock your socks off if you knew.

I never wanted people to "confide" in me due to that list, but that is one effect that it had. I got unsolicited communication all the time. Stuff that I cannot tell you or anyone else in here because it was told to me in confidence. It is also the real reason why I walked away from that list.

So yes, I'd have to agree with you. When you discover failures have occured where you would not have expected them, never would have expected them it gives you a big enough jolt to actually change your perspective.

The same may happen to you.


This whole matter, to a large degree has become a game for some of one upmanship.

I mean look at the very essence of your own post here.

The lines are drawn, and it's coming down to who is on which side.

Trouble is, coming down on the wrong side, could get costly.

When you're gambling with house money, (ie you have a solid warranty) it's one thing. But when you're gambling with your own, then it is quite another.

I wouldn't do anything differently in my position either.

jimbob8915

Quick, give it a rest bro. The aimless GM fans will never hear or believe. Some people I think wish they had more than one set of lips to put on GMs or Katechs butts.

tim414

Most peeps insure valuable items.....replacing one of these engines along w/labor is what? a $20,000 dollar bill.....this is about managing risk and we have all seen across the model years what happens when they pop.

If my Z was out of warranty, I would be taking this approach if there was no warranty. I'd rather spend 3-5k than 20k any day of the week.

3LZZ06

You are correct, now based on those measurements you've just mentioned, not (1) failure has occurred with the tolerances of the guide being .0003 out, and I will venture to guess that you will never see one fail with said .0003 being the culprit.

As mentioned before, .0030 is pretty bad. Some have seen .0300 in their guides and I bet that engine had some pretty obvious clatter going on with the heads to indicate that.

You have never mentioned any clatter coming from your engine that was any different from when you first purchased your car. With .0003 wear on one small portion of three bores your engine was running like "butta" as opposed to some that may sound very "clattery" and "may" need a refresh.

I really have no dog in the fight here and I'm trying to be very objective. I'm just making an observation based on my experience as a precision machinist and IMO your old heads were/are "****"

tim414

'06 Quicksilver Z06

I don't believe that to be the point.

The concern is how much longer, if they are out to .0042 now at 20K miles, will it be be before they get as bad as what you describe below?

Well, nobody knows. But it might cost the owner close to 20K to "definitively" find out should he choose to go ahead with tracking or modding such a car.

Furthermore, to be this close to the edge of the service limit in such a short number of miles, and with some of the guides already beyond the service limit, is disturbing.

Well I appreciate your professional opinion and professionalism.

However I'll tell you, if I had known going in that my heads were in this shape, I would have been crazy to go ahead with my modification plans without addressing the heads.

Random84

Quick, how many more stock failures do you know of outside of The List? This is the first I've seen you mention the not-to-be-named failures told to you over the years?

'06 Quicksilver Z06

I have mentioned it before.

I have account of 7 additional members, 10 engines.

3LZZ06

Truthfully, It would be more disturbing to find the same or worse in your new heads, but allow me to reiterate, with those three very slightly bell-mouthed bores = no concern and no problem running the chit out of it if you so choose.



I do agree that for piece of mind since they're apart anyway, freshening them up completely gives you a baseline if WCCH provides you with a spec sheet for the new ones(?)

I would strongly suggest that after 20K miles, pull them for inspection and compare with baseline. If no baseline has been provided and they have only the wear that your first ones had, you've done well...put them back together with new springs and be on your way for at least another 20K+.