jconnors316

How many z06 owners are running the Ferrea hollow stem exhaust valves?Any comments on them.

aussieross01

I'll let others chime in with more knowledge on this, but the Ferrea's are not sodium filled like the OE:- could that be a problem??

I'd personally like to know have GM redesigned/reworked the OE exhaust valves. I guess if they did they wouldn't own up to it, cos it's like admitting there's a problem with the originals.

Mark2009

Comments are not going to be of much use, beyond the basic facts (weight measured ~ 86 grams, hollow to perhaps 2" above the head, wall thickness claimed ~ .085). Finish is supposed to be excellent, at least to the eye (have not heard an Ra number). Comments on other forums a bit more technical than this one, relating to non-LS7 versions, are that they are tough valves.

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Mark2009

Could be if the lack of sodium overheats the valve seats. Could be an advantage if the guide issue is caused solely by overheated valve stems.

The GM part number for exhaust valves was changed in early 2008. This seems to correspond to an increase of wall thickness from ~ .034 to ~ .043 (actual measurements of the original p/n valve and the later p/n valve).

rockinSeat

I was told that the part number change of the exhaust valve in '08 was due to a change in supplier, possibly related to the bankruptcy period; and that the difference in weight/wall thickness is due to the different process used by the new vendor to input the sodium, and that it was not a change for performance/durability/reliability.

Mark2009

It sounds like you were told more than most anyone could know.

Furthermore, GM filed for bankruptcy on June 1, 2009, over a year after the part number change.

The bottom line is that the newer valve has a thicker wall than the older valve. What that means is mostly speculation, but that it would be stronger seems self-evident.

Overall I would say what you were told was a load

'06 Quicksilver Z06

GM was struggling long before June 1, 2009.

The part number change came in May of 2008. Seven months later, In December of 2008, General Motors submitted its "Restructuring Plan for Long-Term Viability" to the Senate Banking Committee and House of Representatives Financial Services Committee.

In 2005 they had suffered nearly $11 billion in losses, and for FY 2007, GM's losses were nearly $36 billion with sales the next year dropping by 45% .

It is quite possible in the midst of all of this that they could have changed suppliers.

OTOH, I would ask how many, and which, investigators can confirm that there was any change in valve stem wall thickness at all with the part number change.

We know what one guy in here says that he measured. Who else has measured and confirmed the same thing?

Mark2009

And the load grows bigger

'06 Quicksilver Z06

I don't think that many care so much that you say that you measured a post May 2008 exhaust valve by your description; "with some difficulty".

I believe that your words were "I have no ball gauge this small". And yet you want to hold out this crude and inaccurate measurement as "proof" that the wall thickness of of May 2008 and up LS7 exhaust valves, is .009" thicker.

People want to know that your measurements were accurate, and your description doesn't instill confidence in that being the case.

Did you even bother to do a longitudinal section of the valve that you had, as did 240sx2jz in the depiction below?

Come back and tell us that the 2008 and up valves are thicker when you have some actual accurate measurements, the type of which are depicted below. And on more than one valve.

But from your description of your methods, it doesn't appear that you even sectioned the one post May 2008 valve that you had in such a way to even facilitate accurate wall thickness measurement.

If you did a section of a 2008+ valve in the plane indicated below and measured, well then say so. :


No, I'm afraid that's not quite right either. Not all of the 1st generation exhaust valves had a wall thickness of .034" as you indicate above.

240sx2jz shows a wall thickness of up to .039" in that specimen and it is from a 2006.

He shows a wall thickness of .0315"-.032" in the specimen he examined below.

So if his measurements are correct, and there is no reason to believe that they are not, "1st generation LS7 valves" don't necessarily measure .034" in wall thickness.

The fact, is that wall thickness and consistency in wall thickness, has been shown to vary in LS7 exhaust valves.

Mark2009

Folks, this is the problem with trying to misrepresent the positions or actions of others. Especially when you have really taken no action of your own (and therefore might not even understand what others are doing).

As anyone can see, .039 is the max wall thickness of the mis-drilled valve in the photo. The min thickness of the same valve, in the same area, is .029. If you average those numbers, the average wall thickness is .034. Duh.

The ID of the hole in a correctly drilled pre-2008 valve or one that has been mis-drilled as in the photo above will still be the same. And we can assume the OD of the stem will be the same (none have been found/measured with more than a .001 tolerance). Therefore if you subract the ID from the OD you have average wall thickness, regardless of where you measure it or how badly the valve stem is mis-drilled (thin in one spot, thick in the other).

Since the valve is sectioned instead of simply cut in two, that measurement is inconclusive as an average. A machinist could tell you why (there is no need for me to try, for obvious reasons). The proper way to measure concentricity or diameter of a drilled/bored hole in a shaft is to look at it / measure it from one end.... not to slice it lengthwise. If you'd try it yourself, you might begin to understand why.

In any case, it has no bearing on the conclusion that the 2nd gen valve (later p/n) has a thicker wall than the 1st gen valve (early p/n), so all you're doing here is wasting everyone's time. If you can come up with a 2nd gen valve that only has .034 average wall thickness and a 1st gen valve that has .043 average wall thickness, or a 1st gen valve that weighs more than a 2nd gen valve, then you will have a case. Of course, that is not going to happen.
.

'06 Quicksilver Z06

Average??? Where do you say anything in your earlier description in this thread about "average" wall thickness?

What you said earlier was:

The tilde, or the ~ symbol as you have written it above, means "approximately".

I don't see any mention in your above regarding "average" or "mean", nor any symbol indicating such.

And more importantly how is it any consolation to anyone in here who may have one of the above valves, that a portion of their valve might be as thin as .029" on one side?

Seriously, what's next in your line of "reasoning" and excuse making? .001" of wall thickness on one side and .067" on the other for total of .068" of wall thickness and an "average" wall thickness of .034"?

There you go with this "average" stuff again in an attempt to qualify what you said earlier where you mention no "average".

Folks if you take a uniform sized and straight bit and drill a hole into a rod of consistent diameter, but drill it off center, then nobody will have to tell you that areas of your drilled rod, i.e. one "side" of your drilled rod, will have thinner walls than other side of that drilled rod.


Again, you never say anything about the "mean" or "average" wall thickness, and that is not what is at issue when it comes to this matter.

How consistent is the wall thickness is one concern.

How much deviation from the mean do some of the more thinner areas of slightly off center drilled valves show?

I would call a difference of .029 to .039 enough of a difference to be concerning.

And many in here, myself included, are concerned as to how thin the stock exhaust valve wall is at it's thinnest.

An equal concern among some is how thin the valves are at .0034", even when or if there should be consistency in the lumen throughout it's entire length.


Mark200X states in his "research" where he supposedly arrives at the conclusion that May 2008 and up LS7 exhaust valves have a wall thickness of .043" that he made his measurements "with some difficulty" and goes on to say: "I have no ball gauge this small".

Get the best instruments for making the measurements, measure representative samples of May 2008 and up valves, and then you can make the statement that the new valves have a wall thickness of .043".

But measuring one valve, "with difficulty" and using questionable technique hardly allows anyone to arrive at the conclusion but himself.

Even if what he says is true and a smaller bit was used to drill post 2008 valves, then if that hole is drilled far enough off center, you could still end up with a valve which would have one wall just as thin, if not thinner, than the walls of a perfectly drilled pre 2008 valve

So to conclude that post 2008 valves have thicker walls than their predecessors is true, if in fact a smaller bit is being used and a smaller hole made, and if the drilling was done straight enough to prevent one area of the post 2008 valve form being thinner than a perfectly drilled pre 2008 valve.

I don't have confidence that Mark200X could have accurately measured the inner diameter of the valves he cut, nor do I believe that he has measured the wall thickness of more than one post 2008 valve.

By "measuring" one valve, and using **** poor methodology to even do that, by your own confession, it appears that you have not proven at all that "2nd generation" LS7 valves are thicker walled than the prior version of the valve.

Some may be, but others, if they are not perfectly drilled, might not be.

Seeing as how some of the pre 2008 valves were apparently not drilled perfectly straight, that may still be a concern for some.

You "believe"??? and your "understanding"???

So you aren't really certain of what you're measuring.

You mention "uncertainty" in your above measurements, and that is to be understood, considering that your original text, copied below from another post, shows some difficulty in decimal placement:

Why don't you first show us, using accurate measurement techniques, that the wall thickness of the 2nd generation valve is indeed .043"?

Because what you have posted up so far, falls short of that.

Once you do that, well then show us that the wall thickness of post 2008 valves is consistent.

I don't see how you do that with only one valve examined.

If you can't get decimals in the right place, then why should anyone trust your measurement techniques using instruments which call for at least some proficiency in that?

rockinSeat

Heh, that explanation supposedly came from ls7 engineers in GM. I'm not going to defend it, if the person who told me that wants to get in the middle of this, he can. Sorry I mentioned it.

NavyAirTraffic

I run Ferrea F2042P hollow valves, and it's because of what Richard (WCCH) said on another forum when talking about the cause of valve guide wear. Now in that quote he didn't recommend hollow valves (I chose them to reduce weight), if you PM me I can give you the link for the entire quote.

(now ^that^ quote was from 2010, if that means anything to you)

I upgraded to BTR dual springs for the added weight of the Ferrea's over the sodium... to fix the float issue. Time will tell if this thing holds up.

My advice... do your research thoroughly, gather your info, choose a setup and be done with it! There is no long term data (50k miles plus) on any aftermarket fix, so there is no definitive 100% bulletproof "fix".

'06 Quicksilver Z06

When they mention .040", they may well have been rounding their figure up.

240sx2JZ saw a thickness of as much as .039" in an area of example which he showed in here of a 2006 valve.

Also

That's telling me that they have seen as much as .038" all the way down to .032" in terms of wall thickness, and that this thickness may not have been consistent within the same valve. They do not specify year.

The bottom line here is that only one person so far is making a claim that May of 2008 and up valves are thicker than prior LS7 exhaust valves, and he is basing that "assessment" on shaky measuring techniques utilized on ONE valve.

Not only is he unsure of his measurements and mentions their "uncertainty", which should say to anyone that they cannot be trusted.

But he appears to not even be 100% sure as to just what part it is that he is attempting to measure.
http://forums.corvetteforum.com/c6-z...post1572763145

The "9th week of 2008", won't put you into May of 2008. If you're making a claim as to what's what with the valves, a claim as strong as his, well then you need to know what the markings on the specimen that you are studying and holding out to be representative of the rest, indicate.

Either way, be it .030" or .040", the consistency of wall thickness in the stock LS7 exhaust valve is of concern to some professionals.

Furthermore, even at .040" of wall thickness, and even if consistent, there is still of concern from other cylinder head professionals as to if this wall thickness is sufficient.

So really, one trying to tell us that the've crudely measured and that the stock valves are now .04" thick, as opposed to .03" thick, is moot.

propain

Funny how much evidence is constantly missing to support all these debates.

AH says they found inconsistent wall thickness. When asked for the data to support their findings they stated: "We aren't required to share our data". AKA "We don't have it"

We have ONE sectioned valve where we see what is described as inconsistent wall thickness. Nice lines and numbers on a screen. It looks to be inconsistent but who knows. The light is clearly blasting it from one side only rather than straight on. We can see this easily by observing the shadow coming off the valve. This would create, as we can clearly see, a large reflection on one side of the wall and a much more diffused light on the other side. This could easily make one side look larger than the other.

We also have another section from the same poster who sectioned a valve which looks completely fine with consistent wall thickness. Looking at that section the lighting looks to be uniform on that shot as well.

What is the proper procedure to measure wall thickness? I see Mark has pointed out:

Looking at how difficult it would be to slice one of these in half and the possibility to take more of the wall from one side or the other I don't see how this can be considered scientific and agree with his assessment.

I can also see Marks point of cutting it in half and viewing the walls from the end into the bore. This would give a 360 view of all sides of the wall. You can continue to slice in this direction and take measurements for the entire length of the valve. This would also remove the fear of removing more of the wall from one side or the other while sectioning.

Hopefully we can get some real data someday with some independent research from a valve that has not experienced guide wear. Until then all of it is just guessing.

'06 Quicksilver Z06

The troublesome thing that I see in the measurements are already indicated.

And it is that not only is he unsure of his measurements, stating that he encountered "difficulty" obtaining them with his calipers, and it is easy to see just how he would have, but appears to be unsure of exactly what part it was that he measured.

This is why more than one specimen should have been studied by this investigator, as was the case with 240sx2jz, American Heritage, andTanner.

Unless they're lying, all three have examined multiple valves for wall thickness consistency.

Mark2009

Can you link to or quote such concern of any professional? I certainly have not run across any, and I pay pretty close attention to these threads both before and after the sectioned valve surfaced.

Quick, at this point you are actually lying (by misrepresenting the posts of others). That kind of desperation to prove a point indicates that the facts really don't back you up. Now I'm not going to bother to address your wall-of-text posts other than excerpts like above where you seem to have lost contact with the truth, and I would appreciate it if you would stick closer to the truth so I don't have to address read/address those types of posts at all (a flood of biased information tends to contain so many errors that it overwhelms/discourages any attempt to correct them).

That would have been a worthwhile effort; as opposed to attacking the efforts of others. You might have even learned something... but perhaps this eventually entered into the equation:

Flip. Flop.

propain

Its not the measurement. Its the method. I don't know about lying but discovering something of this magnitude should surely be represented with some proper data from the findings. This always seems to be missing.


I did a bit of searching and came up with this as the method to measure wall thickness on a bore. Not sure if it can handle something as small as a valve though.


http://www.envirocoustics.gr/product...ck_mg2_eng.htm


Might be worth the investment if someone is looking to really document some research on these valves. I have a feeling the method of acquiring and measuring these valves wouldn't be considered scientific.

Mark2009

Tanner's never cut open any valves... or if he did he's never posted about it here. What kind of alternate reality / revisionist history are you trying to construct here?

From what I've seen posted here, 240sx2jz cut open two. I cut open three, as you probably know but are clearly lying about. And how do you think he made his measurements? Or do you even know?

As to AH, I haven't seen them post as to how many they've cut open, so once again you are making assumptions or making things up.

How many have you cut open?

propain

With the exception of 240sx2jz none of shown their findings of valve wall thickness.

I have also never seen any results posted by Tanner. AH declined to share their results other than the statement that the wall thickness was found to be inconsistent.