'06 Quicksilver Z06

Subject of debate in here and depends on who you ask.

The people who prefer the OEM, stock hollow stemmed valves, and insist that there is nothing wrong with them, will tell you that it is a bad idea.

The people who have gone above 6k rpm on solid SS valves, and even beyond that and with no ill effects, can tell you that it isn't a bad idea.

But anyone who tells you that it is a bad idea, ask them to point out to you confirmed, real world examples of anyone suffering any ill effect from having done so.

Do know then, that if it were such a "bad idea" well then you would have heard of several in here having suffered a failure as a result.

How many have you heard of to suffer catastrophe as a result of going above 6k RPM, with SS valves in one of these cars?

I have SS valves and wanted to find out for myself. My rev limiter is stock and I've inadvertently hit it during drag strip passes, and have run my car to the stock 7100 rpm limit, with no reservation and ill effects.

Jawnathin

I've run my SS valved LS7 to the 7100rpm rev limit without issue. Both on the street and on the autocross.

lebvette

I do not know, for sure, what kind of valves came in my 69 Z/28, but I shifted at 8K. I do know they were not anything special. So....I do not see a problem with 7K shifts.

propain

Its been said by a reputable vendor on this forum who has lots of experience with the LS7 that running SS valves over 6800 for any extended period of time is not recommended.

Just like stock failures these things take time to rear their ugly heads. I wouldn't put much stock in cars that have two or three thousand miles on SS valves and stating they would have blown up by now or instantaneously as soon as they hit the rev limiter.

The only truthful answer to your question is time will tell. Anyone who tells you otherwise is giving you bad information.

Michael_D

I jumped off a crane with a bungee cord strapped to my ankles at the state fair once....good bit of fun. The next day, a man was killed jumping off the same crane, same set up person, same everything really. They were shut down after that.

7000 rpm for an engine swinging a 4" stroke, running hydraulic lifters and big block sized valves is one hell of a bit of engineering. The valve train wasn't designed by a bunch of interns. I'd be very cautious with the rev limiter if I started adding weight to the valve side of the rocker pivot, but that's just me. I tend to error towards the side of caution with engines. I think 6000 is too low, but would recommend 6600 to provide a buffer for over rev.

Coach62

In my opinion, yes and I will probably get beat up over this. I did a lot of research before deciding to use the new revised OEM valves for my WCCH build.

Besides what Jason at Katech said, I talked to a REV valve engineer that was VERY helpful. He basically said those solid SS valves are really meant for high temp applications such as turbos. After talking to him, he said that if the bounce specs that Jason reported are accurate, that amount of valve bounce can definitely cause valve failure.

Besides, the hollow valves are significantly more expensive than the solid valves. So the obvious and important question is - why would GM spend the extra money on these valves if they didn't think it was necessary?

Coach62

'06 Quicksilver Z06

Glad to see that this example pointed to in the first post of this thread, turns out to have had the CHE rocker upgrade, BT Platinum dual springs, and the stock rockers too, as there are a lot of people who run the same, or similar, setup with these particular heads.

Curiosity got the better of me on this particular case, so earlier today after watching the video that maligator linked us to, I spoke with Chad regarding the condition of not just the guides, but the springs and spring pressures, seals, etc. and was glad to learn that he had also evaluated these.

I was glad to find out that these all looked good, and checked out as well. I looked at my own spring pressures and these were consistent with what mine were when freshly done back in August of 2012.

Negative signs of valve bounce was good to know, when we have heard so many theories in here on it.

What are the new revised OEM valves Coach?

What is different about them?

The last "revision" that I know of for the stock valves came May of 2008 of I recall. And that "revision" was a part number change from all that I can tell. Was there a revision after that?

Coach62

Well I never verified this, but it was my understanding that it wasn't just a part # change, the thickness of the valve stem wall was increased.

Coach62

BTW, REV does make a hollow stem valve that is about twice as thick as stock, a bit heavier than stock but much lighter than solid stem. It is NOT sodium filled.

To me, this seems like it may be the best of both worlds and may be the best valve going forward.

Also, you said that there were no signs of valve bounce. What would those signs be?

'06 Quicksilver Z06

Since you have to be careful putting stock into low mileage SS valve setups and their results, you might want to look at the following to help you with your answer.

http://forums.corvetteforum.com/c6-z...woot-woot.html

In this thread, the guy is asked at least twice if he is running SS valves.

He finally gives his answer in post #33.

Also

http://forums.corvetteforum.com/c6-z...post1585466074

I'm thinking that if these guys can run like this with SS valves, that they'll do the job, and do it reliably, at over that 6K RPM you were asking about .

Thanks for your reply, as I have also not seen where anyone has verified that. Not saying that it is not the case, just that I have never seen that the part number change reflected with an an actual increase of any wall thickness specifications of the stock hollow stemmed LS7 exhaust valve.

I have seen five reports, or comments which center around concerns of the actual valve stem wall thickness of the stock exhaust valves.

The first I recall seeing was by Brian Tooley.

Then there was the report by 240sx2jz of his findings upon sectioning a random stock LS7 exhaust valve.


Then report of other evaluations and examination with regard to the thickness of the OEM stock LS7 valve stem by one of the new forum vendors offering cylinder head service here.

Another forum member in his thread, posted this up, and mention of valve stem wall thickness is made in his post as well.

And finally a concern and an observation made by Chad around the same area where the YouTube video being discussed in the first post of this thread was introduced.

So some have observed, and expressed concern over the wall thickness of the stock hollow stemmed exhaust valves.

The best thing to do, would be to go over and ask him. I knew of tuliping and valve deformity as signs, but better you ask him for any other examination he did, and explanation, in an effort to determine if there had been any valve bounce and the manner in which the car had been used. He told me what he looked for, and I am sure that he will tell you.

I asked him his thoughts on motor oil, which motor oil had been used in this case, (his answer was interesting) asked him about the condition of the valve seals, the springs themselves, the pressures, etc. I would recommend that you do the same thing for your best answers with regard to this case.

You can make an account on the forum where he is a member and where the bulk of this case is being discussed, and where that video was introduced.

I've kept in periodic contact with him and phoned him to get my answers and ended up talking to him today for over an hour. While I was talking to him, two other people called him.

But that is not going to be practical for everybody, so what I suggest to you above with regard to just making an account and asking him, that would be easiest as opposed to me conveying what he mentioned with regard his evaluation of what you are asking about.

Mark2009

Depends on whether or not the valve springs can handle the extra load. But consider this:

Say you have to catch a 10 lb. bowling ball, dropped from a height of 10 feet, every day. 5,000 times a day.

Now say they increase the weight of that bowling ball to 15 lbs. Do you think that will put any additional stress on your body?

Would you prefer the heavier ball be dropped from 8 feet instead of 10? (6500 RPM instead of 7000)

Food for thought . . . . .
.

Mark2009

Do they make this for an LS7, and if so what is the part number?

Mark2009

That is correct.

Dirty Howie

Obviously, I am a big supporter of Richard and WCCH so am happy to see this video from Chad. And even happier that I have WCCH heads on my car. Usually, Chad is posting vids of heads completely out of spec. It never hurts to have work done by one of if not the best head shop anywhere. WCCH head work is beyond reproach, utilized by many of the best specialty shops and has stood the test of time under the most harsh track conditions.


DH

'06 Quicksilver Z06

Source???

Coach62

Yes, they do make this valve for an LS7. The engineer verified this, I believe his name was Scott???? Sorry, do not have a PN, but if you call REV I'm sure they can look it up. I'll see if I can find my notes, I think I have his name on them.

I made the point to him that since it was a newer part, I didn't want to be the guinea pig. His response was something along the line of: "We've been making hollow exhaust valves for over (20 years???). We're no newcomer to this, we know what we're doing.

As pointed out above, the GM exhaust valves are around .030" thick at the sidewalls. I believe theirs is .060 or .070 thick. I left out one very important point BTW. The OEM valve weld is just above the valve head. REV makes their weld high enough that it will be up inside the valve guide. I think this is huge - IMHO.

Their engineer really impressed me, being an engineer myself (electrical). He said the valve bounce is serious as it sets up harmonic distortions that can cause stress to the valve and cause failure. He was very firm and direct in this assertion.

The ONLY reason I didn't go with that valve is they had not spintron tested it. Had they tested it, I would have hands-down bought that valve.

Dirty Howie

Not true !!! I have 22K miles and 12 track days on my WCCH heads. I regularly rev to 7K RPM or close to it every chance I get. Plus there is no performance penalty. I get to the same top speed on every point on each track I go to as I did with the stock heads.


DH

Dirty Howie

I am not beating on you for your decision to use OEM valves. I was actually at WCCH today speaking to Richard. He showed me the new OEM exhaust valves. They basically have some machining on the top of the valve but still the same welded application. I asked him if he was ready to advise anything different than what he has been using for years and he said no. He pointed out that his heads are routinely beat on with very large cams and never sees any heads coming back. You can't argue with success


DH

propain

Food for thought, one guy running 8's on SS valves is not a reason to blindly think they will have longevity.

I can make a gocart run 8's. It will probably blow up on the 2nd run.

So yes, even with such a compelling sales pitch I will still be waiting for longevity out of the SS setup before I buy some shares.