rockinSeat

Answers to your follow up questions - I called again today.
What is wrong with the OEM valvetrain? Cannot say for sure - they have not seen enough heads. They have seen guide wear. Guide wear is due to bad guide (mis-centered or problem with surface material) or bad geometry (doubtful because of long line of LS motors). Will ask contacts for more info.

Why do LS6 engines not have valve problems given they have similar exhaust valves? Agree, LS6 not having this problem. Believes this is because they don't have the mystery problem with the guides.

How many LS7 heads have you worked on? Only about a dozen sets of heads. If it is warranty work, stock parts are of course used. Non-warranty work is your choice. Most business comes from Des Moines area dealers. The shop sees racing business from throughout Iowa. Have far more LS1/2/3/6 customers.

What springs do you recommend? Comp dual springs.

Will there be any high-revving issue with Stainless Steel exhaust valves? No, not concerned about changing valves.

Do you have a Spintron machine? No, machine would be used for designing a valve train or R&D and does not pay itself off in our line of work.

What brand parts would you recommend for me? Comp dual springs, CV bronze guides, Manley or Ferrera SS exhaust valves, stock intake valves, Comp roller rockers.

My mistake, it's 35 years experience of building engines and cylinder heads.



Fixed original post:
All, while back home for the holidays, I spoke with my father's mechanic about the valve train issue. He referred me to Jeff Piper, manager of Harvey's Machine Shop in Norwalk, Iowa, who has 30 years of experience with cylinder heads. I spoke with Jeff today and it was quite refreshing to converse with someone who knew exactly what I was talking about with regard to the LS7 valve situation. Jeff's shop does the cylinder head repairs for cars under warranty from many of the dealers in Iowa and he has had about a dozen LS7 heads come through the shop. I will soon be out of warranty soon, so for me, Jeff recommended new guides, stainless steel valves (better than 2 piece/hollow), and new springs. As for rockers, if you have to stay stock for your racing class, he recommends installing the trunnion kit. (He was also familiar with the needle bearings issue, so I knew I was talking to the right guy). If not staying stock, he recommends roller tip rockers, as these would have alleviated many of the problems seen from the factory. Jeff also mentioned that the factory springs should be replaced and that you have to be careful to select a spring/manufacturer that can do the job as there are may out there that don't.

I didn't get a quote, but the rates seemed very reasonable and I could reuse my cylinder heads without worry. I just wanted to make sure those Z06 owners in Iowa are aware that there is a local shop that is familiar with these issues that would be happy to do just the head work or take care of head removal/replacement. Jeff said the LS7 can be a great motor once the valve train is fixed, and that I'd be good for a 100k miles. I feel much better about the situation and will be doing this in the future. In the meantime, if you are in Iowa, definitely check this shop out for having your heads fixed.

Here is the contact info:
515-981-4209
http://www.harveysmachine.com/

Vette @ 71

Disd he say what specifically was wrong with the OEM valve train...?

rockinSeat

It was hard for me to keep up with him considering I am not a mechanic, but I believe he said something about problems with the guides. With 30 yrs of experience he was able to tell me all the pecularities about chevy small block v8s over the years and that Chevy made several poor decisions with the LS7: 1) use of 2 piece valves, 2) no roller rockers, 3) factory springs may not be enough for all-out use. I'm trying to send him an email and I will pose the question. One other thing I should mention is that he thought doing wipe tests or valve wiggle tests would be extremely difficult. He says most of the wear occurs at the bottom of the guide, thereby making the wiggle test less meaningful.

Oskee

Great Info !

Gary '09 C6

MTPZ06

Ask him why the 2 piece valves aren't problematic in the LS6 as they appear to be in the LS7. I'd like to hear his response...

Dirty Howie

Did he mention any spring sets that he likes?

I am glad to hear he told you the same thing Richard at WCCH told me ............ "should be good for 100K miles"


DH

'06 Quicksilver Z06

30 years of experience.

Does he have a spintron?

It is interesting that he knew exactly what you were talking about, since some say that this matter is "overblown".

Here you are in Norwalk, Iowa and they know about it.


It is good that you don't have to send your heads a long distance off in order to get them upgraded. And not only that, they will do the removal and replacement of the heads for you.

Good on you for doing the research and making some phone calls and talking to professionals with three decades of experience, instead of listening to some of the other stuff in here.

Great post and a huge help for anyone in your area needing this kind of work.

'06 Quicksilver Z06

And I don't think that it is a coincidence that more and more shops are seeing this, and going about managing it the same way.

glenB

So we're back to blaming the failure on guides and two piece valves, again.

These are the same guides used in countless other non LS7 heads and the two piece valve has been in use long before anyone heard of an LS7.

Using a one peice valve is just a crutch for the real problem.

To say that not using a roller tip rocker leads to these issues is not telling the whole story. When looking at the swipe pattern of many of the pics posted cleary shows that the pattern is off and even a roller tip won't correct it, it only delays the wear by reducing friction.

Mookster

...has had many LS7 heads come through the shop...

Really? With the total of two Z06s in Iowa...perhaps they have many customers from middle east

97Black

I would like for all these repetitive posts to be stopped unless there is an absolute positive answer what or if there is a problem and what that fix is. Reading about opinions and arguing over the same posts is past the point of obscene. Maybe the moderators need to step in from now on.

rockinSeat

LOL! Nope, but I can tell you there are more Z06 owners than Z06 forum members. Hopefully, they'd find this by google or something.

rockinSeat

From what I could deduce, it sounded like if work was being done for a dealer under warranty, then the 2 piece valves go in, to remain in a factory configuration. If not warranty work, then its your choice. I thought I heard the two piece valves would be fine once the guides are fixed, but there is a reluctance to put them back in. Along the same lines, the stock rockers are fine once the guides are fixed, but the roller tip rocker would have been better in the first place, etc.

rockinSeat

I agree this issue is depressing, let alone boring and repetitive. The main purpose of this thread was to alert folks in Iowa that there is an experienced shop that is familiar with this problem and I am sorry I included details about my conversation. I will tell you that after talking with Jeff, I have renewed confidence with my car and I know what I'll be doing - that's really why I wanted to share. Moderators, if you are listening, I'd like to see a sticky thread that has the following info:

1. What the problem is
2. How to tell if you have it
3. What to do if you have warranty vs. no warranty
4. A list of reputable shops that can perform the work in various regions.
5. Disclaimer

I think that will be the way to put this to bed.

Thanks, Sean

Bill Dearborn

Only one thing concerns me about the credibility of the information and that is the so called experience with the LS7 where it is stated the shop has seen many LS7 heads. Just how many Z06s or LS7 engines have been delivered to Iowa since 2006? Total population of the state is about 3M. Assuming an even distribution of Z06s across the US population that means for every 11214 people in the US there is 1 Z06 (314M divided by 28K). That rough calculation indicates there are only 267 Z06s in all of Iowa. With a failure rate of 5% (is it that high yet?) that means the shop might have seen 26 LS7 heads. Does that qualify as many and does it qualify anybody to be an expert in how to solve the problems if as stated most of the repairs were to return the heads to stock form. If we assume a bare majority of 14 heads were returned to stock format that means a maximum of 12 (6 engines) could have been converted to stainless valves. Of those 6 engines how many have been torn down after 15K miles to see if there is any proof the solution has worked? 1? 2? More than likely if the engine is running well the owner isn't going to have it torn down to see if the solution worked. Assuming the worst case scenario and they didn't solve the problem and end up with the same assumed 5% failure rate of the stock valves you don't have much to work with. Five percent of 48 exhaust valves means at least 2 valves might fail within 15K miles or a max of 2 engines and then how many miles have those engines been driven in Iowa over the last x years? A well used Vette probably averages 5K miles per year in a state where the cars are stored for the winter.

I tried to make these numbers worst case so the results would show more cars are impacted but even then the numbers aren't sufficient to make any conclusions.

Bill

'06 Quicksilver Z06

They could be seeing cars and heads, from surrounding areas and outside of Norwalk, IA.

Kansas City is only 180 miles away, Omaha Nebraska about 140 miles away.

If their reputation is good, and after 30 years, it would seem to be, then they could easily be seeing cars from further away than that.

You look at the states which border them, South Dakota, Minnesota, Nebraska, northern Missiouri, western Illinois, western Wisconsin, it is not unimaginable to me that they are seeing a good number of LS7 cylinder heads. They look to be one of the only big shops in that area.

Given the above, I believe he has seen a dozen sets of heads.

Vette @ 71

Try viewing there web site?? Almost useless..Could be a great shop however..Agree with your worse case assumptions..Another solution with no stated failure mode(s)..

MTIRC6Z

Yep you really need to get all those defective stock parts out of there and do stuff like upgrade to solid stainless valves, for sure, every Z06 owner is nuts if they don't follow Ricky's lead so they too can sleep better knowing they wont ever blow anything up

Of course some people might not view a 100k fix as an upgrade, particularly the ones who have gone over 200k on their STOCK parts

http://forums.corvetteforum.com/c6-z...000-miles.html

Cheers, Paul.

HyperX

People say you cant get high revs with SS valves, is this true?