Mark2009

In the interest of complete and accurate information, as best we can determine here on CF the 'upgraded' valve (new part number) entered the system on May 2008, which -- depending how many of the original valves were in the supply line -- would put them in late 2008 model year cars (probably not too many) and up, or about 8,000 more cars than the 1,902 implied in another post (2010's - 2012's). Plus the 2013's and the 427 Verts, maybe another 500-1,000 or so.

Of course we have nothing but pure uniformed speculation that the upgrade in wall thickness had anything to do with the failures, but from a consumer point of view it could hardly seem to hurt.

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Dirty Howie

I will be very interested to see what you decide after talking to Richard. Since his shop is about 30-40 minutes from my house I have actually spoke to him in person 3 times. Somewhere you can find my thread with pictures I took of his facilities when I picked up my heads earlier this year. There are stacks and stacks of heads from shops all across the country and internationally as well. I told him to build my heads the same as he would do if it were his own car. He has complete confidence in his product. I'm sure you will be very impressed when you speak to him, everybody is


DH

Coach62

Lots of good info here, thanks to everyone. Learned a lot, still have more to learn. I have to say reading all the links Quicksilver posted has made my brain cramp up.

briancb1

The "valve float demonstration" was done on a mock engine. There was no cylinder pressure being built or released, which acts as an opposing force to the exhaust valve during the exhaust stroke.

Both my cam grinder who's been doing cams for 20+ years and Darin Morgan (who did my heads and springs) said my solid exhaust valve would be fine for the OE operating range.

Mark2009

Two critical things to consider when analyzing data:

1. That a testimonial is not data.

2. That absence of evidence is not evidence of absence.

Oh, and last but not least but since it wasn't specifically mentioned in your OP it got overlooked -- if a cylinder head has no guide wear and no other evidence of distress (damaged spring seats evidencing repeated valve float, for example), then there is no sound engineering reason to expect a valve to fail.
.

Mark2009

This post is a perfect example of my previous point... it is telling you to ignore data and instead rely on a testimonial.

What it is not telling you is that the "mock engine" is a highly sophisticated machine that is used for valvetrain design and analysis by several highly respected names in motorsport, including Comp Cams (they have several of them) and NASCAR teams.

See http://trendperform.com/spintron/about/ and http://www.cpgnation.com/forum/spin-win-5216.html

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'06 Quicksilver Z06

Put me in, Coach. .

One thing I would recommend since you'll be talking to the people you mention, is to make a list of questions you want answered.

I mean, how many times do you hang up and end up wishing that you had asked this or that?

I'd make a list of questions.

Among them you may decide to inquire about, is the lubricity of bronze alloy guides vs that of powdered metal.

You may also wish to inquire about, or if you've read the forum, may have already heard about, aftermarket valve guide length vs standard valve guide length as well.

You still have a good bit of research left to do, and it's a lot of fun doing it but along your journey, do know, that as much as this matter is sometimes presented as such, it's not so much "rocket science" so much as it is "horse sense".

Good luck Coach.

ConfusedGarage

I am one that has switched to WCCH heads with Bronze guides/OEM exhaust valves replaced new/Katech Timo intake valves. My car's guides were all in spec at 17,000 miles (15k were cammed and 550 rwhp), valves looked new, quiet drivetrain. On the new setup I have only 8,000 miles, 7 dyno pulls, 1.2 track hours, 20 drag passes, and about 20 mexico roll races. More to come and all good thus far. The old setup had 75-80 passes on it, 14 dyno pulls, and about 35 mexico roll runs redlining 1-2-3 and sometimes 4th, so it was used.

As for not seeing failures on heads redone, that all depends. We have seen a few failed lifters on all different setups. Now lets say a particular example has a heavier SS drivetrain that had a lifter fail. Does that heavier valve setup still receive credit for not dropping a valve? Yes. If it were the culprit of the dead lifter, would it receive that credit? No. I think a good data point to watch is Dirty Howie. He has WCCH bronze/SS, and if he doesn't fail a lifter or anything in the next few years, that setup should be fairly proven.

There are intake valve failures mixed in with exhaust valve failures, and a whole ton of guides worn well out of spec prematurely. If there werent cases of guide wear running rampant and valves were exploding with in spec guides, I'd have a different opinion. However, I am not swayed and influenced by anything that isn't supported by data, ever. So digest that how you want, nobody has any conclusive data other than knowing the stock guides seem to wear prematurely about 90 times out of 100. That doesn't bode well for any valve. Do what you want but check the guides.

Michael_D

I find little reason to think the solid stem ss valve and bronze guide will not live a long happy life, IF machining and geometry is spot on and the correct spring package is used and set up correctly. The peak rpm is my primary concern. You can not generalize valve train stability discussions. Too many variables to concider. That is where testing comes into play. To ignore testing results or poke fun at them is just plane stupid. Anyone who does either should not be listened to.

I also tend to take second hand conversations with specialists reported on forums with a grain of salt. They are often missing very important parts of any given conversation, or twisted to support the poster's prefered bias.

Minkster

DH,

As I mentioned before, the dealer told me that they had no idea what caused your engine failure as the motor wasn't opened up. Don't think it is right to assume that valve drop was the cause of your original failure without solid proof. Just sayin.....

Dirty Howie

I don't think I told you this before but when I was on grid before my motor blew, a couple of guys noticed and told me later that my car was puffing smoke from the exhaust.

I believe the smoking was because my guides were shot, which led to valve failure.

I don't know that very many motor failures at all are known with solid proof, even when the valve head is missing. But I do think that bad guides will cause valve failure, not oil starvation or other modes of failure.

My new 2011 motor replacement also had bad guides after only 33K miles.

And for the record: I don't believe I ever refer to my motor as "dropping a valve". I always say it failed or blew up. I think many infer it dropped a valve based on the guide issue and I think that's the most likely cause in my mind too.


DH

Minkster

Fair enough, but the cause of your motor failure is listed as "dropped valve" in the "list". Puffing smoke from the exhaust can be anything from rings to guides, especially after nearly 90K miles of being pounded on, so who knows there. The last time I had bad guides ('71 LT-1 Vette), the only time it smoked when I was backing down, idling hardly anything showed. And I'm pretty sure the burnt journal and the absence of both the rods/pistons that were connected was pretty solid proof of oil starvation in my old engine (I can laugh now).

I believe you had a set of the incorrectly milled heads in your replacement engine since the engine build date was right in the window of suspect heads. That milling error would have been corrected when they were milled for your new guides IMO.

Agree with your previous statements and the inference some have taken to make assumptions. Just wanted to be sure what was what.

Dirty Howie

I thought my heads were in the good-safe build date range

Glad your finally starting to smile ...........


DH

Mark2009

Well, that's interesting

Oh, and as to your wallet, wasn't your engine covered under warranty, Howie?

Coach62

I'll get into more detail when I have some time. But - my discussion with WCCH went well, they do inspire confidence in their product. I was actually considering going the Texas Speed route, but believe I'll stick with the WCCH.

You can tell when someone is BS'ing you and they sure don't come across that way, and they have no problems spending all the time you want talking to you. You don't have to ask many questions, they've heard them all before and anticipate what you're going to ask.

Bottom line is you just don't buy a product, you buy a company and the person behind it. If you think about it, the last thing they want is someone coming on here saying that they lost a exhaust valve and blew an engine with their heads on. They're going to do what they think is best and will hold up best. If they think XYZ valve and/or spring is better, they have no reason not to go with it.

Bottom line is I did a Howie and told them to build the heads like they were building it for themselves. I can always check the heads in a year or two (no more than I drive it).

I certainly do appreciate all the input and thoughtful comments and opinions from everyone. I own my own business so I understand the last thing someone wants to lose is their reputation.

'06 Quicksilver Z06

I think you're going to end up with a solid build from Redline Mororsports.

But more importantly, through your research you've gained confidence in your plan, and in those responsible for helping you implement it.

I expect nothing less than the best results for you.

Coach62

I think either valve is a good choice as long as the guides are changed out. I "might" go to FI some day and feel the SS valve is a better choice for that application.

Also, according to WCCH .015" bounce is acceptable by Comp Cams standards. I plan on verifying that, but assuming it's true that says a lot.

Either way, I figure in a year or two we'll all know a lot more. If I made a bad choice then I can correct it at that time. Maybe even go with an all out forged build if Obummer doesn't completely screw up the economy by then.

'06 Quicksilver Z06

He may have been referring to the following:

http://books.google.com/books?id=nlM...page&q&f=false Last paragraph of page 113, first paragraph of page 114.

This book cites Comp Cams research which considers valve bounce beyond 0.020" as "more serious valve bounce problems".

When I was running those listings, it seemed like even in the rare case that one car go should off the stock or modified listings under the failure category of dropped valve, the uncanny thing was, that there was always room for one more to take it's place. Stock or modified.

http://forums.corvetteforum.com/c6-z...post1581399328

I remember back in 2011 when your incident first happened Howie.

And many of us in here who are familiar with your story, know that it was well in the balance as to whether or not it was going to be covered by warranty.

Without getting into specifics on the circumstances behind your warranty repair, people should know that it was far from a given that warranty was going to cover it.

At any rate, I am glad to see that the discussion remained civil, and that Coach had his questions answered.

Minkster

I thought your motor was built near Feb 11 (when GM indicates the issues was "contained") which means the heads were built prior, so thought they were suspect. Anyhow, you've had them milled now which would have fixed any milling error that existed, so you should be fine as far as guide/seat alignment goes.

Yeah, I can laugh about it now, but it took a while to get to this point.

Be safe at the track.

FSTFRC

OP call shops like you did and get the answers from them... There is good information and talent on this site but you have to weed through the BS sometimes...

This is Darren Morgans website notice all the teams he has worked for over the years and he even did work for GM (IRL Racing, head work) at one time. Plus all the published papers in magazines just like another company on this website... http://www.darinmorgan.com/dmch.html