stefuel

With all the buzz around here about the "valve issue", the one thing I don't recall reading is if anyone has tried sourcing a higher then OEM grade sodium filled valve Surely there must be a same design but higer quality valve to fit the bill?

Mark2009

1. Surprisingly, no. People freaked, with no small amount of assistance.

2. However, despite some observed individual discrepancies there has never been a defect associated wtth the OEM valve that would cause the typical failure.

Hib Halverson

Currently, there is no "higher-grade" hollow-stem, sodium-cooled exhaust valve for an LS7.

For a revision of my LS7 article, which is posted at another Corvette forum site, I contacted Del West, the supplier of the Ti intake used in LS7s and which makes sodium-cooled exhaust valves for other applications, and asked if they could make a premium exhaust valve for the LS7.

My contact at Del West said that his company could make the part but that the business case to do so was not there. He said the demand was low and the company didn't have the marketing resources available right now to support introducing such a product.

blkbrd69

Not quite true:

After finding one of my removed valves was lighter in weight than the other 7 & had a different color to the head and shaft I milled it open.
Didnt get the sodium reaction I expected, so I opened a few more.
Appears the one that was lighter had significantly less sodium than the rest, the wall thickness and weld quality seemed to be sub par also.

This valve had much greater wear on the guide than the others, one could extrapolate it was a manufacturing defect just waiting to snap.

Note to anyone that cares to duplicate this machining. The valves are very hard, sodium makes a mess and is dangerous especially in a humid enviroment. Plan on using up some expensive endmills.

Mark2009

Wild speculation; no place in an engineering discussion.

blkbrd69

I guess as an Engineer, Machinist, Welder, Engine Builder & Aerospace QC inspector I should not speculate?

Form a theory or conjecture about a subject without firm evidence.
Grain scale, Micrometer, Optical micrometer, Microscope what else do I need?

MyLastCorvette

You will find mass amounts of information in the twice closed thread titled;

"GM Response To LS7 Valve Guide Issue Summary Confirmed."

Or you could contact the experts.
1. Katech, Jason
2. WCCH, Richard
3. AHP, Kohle
4. Lingenfelter Performance just to name a few.

There are likely many more competent shops, these are the ones I have talked to, when selecting who would re-do mine. If you do any research you will find posts, by we, who have addressed the issue; And whom we choose to do the machine work...

Dirty Howie

I know this was declared an engeneering discussion but even though I am not an engeneer that doesn't prevent me under CF rules from adding my two cents

Seems pretty obvious that there are at least three critical steps that are all subject to manufactoring error in the OEM valve.
1. Drilling out the stem
2. Welding the head to the stem
3. Getting the sodium in the correct amount into the stem

Obviously, none of these are concerns with a solid SS valve. Maybe this is one reason so many shops and owners select SS exhaust valves.


DH

Dirty Howie

Well imagine how I felt when I read it

Any ways, I don't think you have anything to worry about with the titanium valves installed by the best head builder around


DH

Mark2009

It's the internet; you can be whatever you want to be.

Regardless, your post was a collection of undocumented, misinformed speculation presented as fact; hardly the forte of an engineer.

The first 3 words of your post were false. QED.

blkbrd69

IMHO The valve "was" engineered properly.

Multi step manufacturing process is a build up of possible errors.

Multiple possible errors and minimal QC =

Mark2009

More clueless speculation. And there is evidence that the weld is NOT at the head. When it comes to engineering, RUN away from posters dreaming up imaginary faults/'facts'.

Mark2009

Numbers. Show us the numbers from your inspection/dissection.

blkbrd69

Why?

From what I have seen people have formed there own opinions without doing the hands on dirty work themselves.

"there has never been a defect associated wtth the OEM valve that would cause the typical failure"

That "typical failure" which is multiple valves snapping just above the weld. Or maybe none broke and the whole thing is a fairy tale?

Aside from my time and money using my personal milling machine and tooling to personally find out why there were so many incidents that I had personally seen the results of.

Easy to engineer the perfect component.

Not so easy to follow it through the purchasing of raw material, multiple manufacturing steps then also ensure the quality control process is held to a high standard through multiple companies and locations. All the while not spending too much money on them as they are mass produced parts held to a profit margin.

Dirty Howie

Really?

Why would anyone run away from my post which is not clueles speculation but in fact is just commone sense.

Are you saying that there is no chance for induced errors when:
1. Drilling out the stem
2. Welding the head to the stem
3. Getting the sodium in the correct amount into the stem

Are you disagreeing that none of these steps are necessary in a solid valve thereby making it a defacto more reliably produced valve?


DH

rockinSeat

A while back, there were pictures posted of a valve removed just in time, as there were visible cracks down low where the hat meets the stem - no where near as high as where the weld is. It wouldn't have mattered whether the stem was filled with steel, sodium, air, or jello for that matter. If left in service, the valve was going to break down low where the cracks were. According to the picture, all the valves are solid where they break anyway, so why all the arguing?

stefuel

I can't remember the name of that thread but seem to recall the poster cross sectioning that valve to inspect it.

'06 Quicksilver Z06

You guys are talking about two different threads.

In one forum member 240sx2jz showed a sectioned valve with inconsistent valve stem wall thickness. That's the thread you're referring to.

In the other, forum member Dirty Howie showed at least one stock hollow stemmed exhaust valve which had stress cracks in it.

This is the thread rockinseat is referring to.

At any rate, neither of the above would tend to instill the greatest of confidence in terms of resistance to failure

rockinSeat

]

Hey Quick,
If you have the thread or the pic of the stress cracks handy, would you mind posting the link? I couldn't find it.

Thanks

Mark2009

Instead of trying to build a better mousetrap, which could probably be done (prepare to buy a batch of 200 or 1000), I'd suggest the following improvements to the OEM valve:

1. Polish neck area to remove stress risers.

2. Polish tip for less friction w/rocker arm (polish rocker arm tip too).

3. Maybe polish stem depending on current finish.

That should reduce guide wear and reduce opportunity for catastrophic failure.