adamgl

I would say it affects every year of LS7.
There are a few measured and out of spec '12's and '13's.

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

MyLastCorvette

Still swirling in the "Sea" of uncertainty. (Which replacement vendors heads vs C-7 maybe a Ford, just kidding) I was told by Lingenfelter, they have had -0- failures with their replacement heads using stock GM parts; Installed in a correctly set up CNC head. PS But I still "Know Not What To Do."

Vette @ 71

How many have they done??

MyLastCorvette

That is something I forgot to ask; As I draw nearer to addressing the issue I will call back and ask. PS Will then post his answer...

MTPZ06

I find it believable that they haven't...if the issue truly is nothing more than a machining error from GM, Lingenfelter's rebuilt heads should fix the issue with proper machining. Look at the LS6, same essential valvetrain design...beehives, needle bearing rockers, PM guides, two piece sodium filled exhaust valves, etc. No valve issues on that motor...and its a workhorse at the track.

MyLastCorvette

Agreed, I have had more than one aftermarket vendor say the same; Bad machining of the guides, through the outsourced GM supplier. Damn it just kills me thinking about tearing into my engine...

clogan

Don't sweat it. Let a good shop do it for you. I took mine in to an LS7 specialty shop one morning at 9:30 or so, and it was ready the next day before lunch. New heads, valves, guides, springs, et al. Cost me less than a couple sets of tires. One day turn around: about what it takes for me to get a suit dry cleaned.

Makes a bit more noise now, and mpg is a bit less (edit: should say "better") on trips, but the peace of mind is really nice.

Frankie2blue

I'm with you there. I am still waiting and watching for some more definitive answers, along the route of keeping mine stock. I do not want more HP and I do not want an altered design. I just want it to be correct OEM and trustworthy. My car is 08, never seen redline ever and has 8000 miles. Quiet as a church mouse and burns no oil, but I realize that is an indication of nothing.

Z06hopeful

With the way you describe your car, the only difference between you, your car, and me is vehicle color.
But you know, since I had that electrical issue.. posted here and some great advice, I realize that this is still a car, garage queen or not, and things will happen. Since GM has hesitated to help, and even if they did, finding a good dealership????, we are going to be left to our own devices.
I am reading all posts, seeking the repair strategy of posting vendors, and when I am ready, moving on that discovery.
Right now, it looks to me like AH has the perfect solution to addressing problem and still staying relatively stock. Just my thoughts.

Frankie2blue

Yes I have been watching AH and their use of PM guides, but I would like to use OEM valves if possible to keep everything stock. Lingenfelter seems to go that way, or I would consider Katech also. I don't think I want the bronze guides and all that. Most people doing heads seem to be interested in HP gains at the same time and I am really wanting it OEM as designed. This issue alone and GM's handling of it has pretty much quelled my interest in purchasing a C7 Z06, even though I really have been planning on ordering a second year Z. Without even a definitive answer from GM on this issue, I am no longer ready to jump into a new Z and get thrown under the bus again on whatever the next big issue will be that they want to avoid dealing with. People can defend GM all they like, but it is a travesty that we have to tear down a nearly new engine and have to try to decide on our own what the best fix may or may not be to make our cars dependable. I stopped doing car shows because I got tired of all the questions about the friggin valve issue. Sorry, but it's not right.

Z06hopeful

Yes.. see your point
Think as of now my choice will be stock Ti intake, polished, that new bronze guide material they are just putting out, Ferra hollow stem SS exhaust... and if it works, stock springs, Ti retainers.
Now to decide on rockers, seat material, and if shaft mounted rollers make sense.
Then get tune, and hopefully rest easy.

AzDave47

Stock springs probably are too light a spring rate to deal with the hollow SS exhaust valves as I believe they are 6-10 grams heavier than the stock exhaust valves?

MTPZ06

We'll soon find out... https://www.corvetteforum.com/forums...on-thread.html

Dirty Howie

You mean those that donated money to the testing will find out soon. The rest of the Corvette comunity will be left in the dark


DH

propain

Are you scared of the dark?

Old Boot

2013 just passed 10K, I use the rev limiter to know when to shift LOL.
Like I said before, 2013 has a 5 year 100K warranty. I don't try and kill the car but I do drive it like it should be driven, Im hoping GM got it right in 2013 but if they didn't Ill get work done with the warranty motor so it wount have the same chance as the original motor to break.

MyLastCorvette

UPDATE:
After calling Lingenfelter back they said over 2k, he didn't know for sure without checking. ZERO failures with proper machining using all stock GM parts...

My Z-06 is scheduled for valve train inspection/tear down Monday September 15. They and I feel, the only way to completely accurately measure valve to guild clearance, condition of valves, is heads on the bench.

So here is how it's supposed to go. Since I'm on extended warranty (until 1/04/15) any valves that are found to be out of GM specks, they are going to attempt to run a "Stock" repair on both heads through the warranty program.

If the valves are within GM guild lines, I will be covering the complete cost, at that point, will likely be heads similar to the Katech heads they offer as option #3. Bronze guides Ti/Mo intake and exhaust.

I think it VERY POOR customer loyalty/payback, and have called GM customer service to voice my opinion. Do I need to say, THEY are very sorry for my concern; But there are no current plans for a RECALL on the LS-7 engine/heads...

Dirty Howie

Not anymore. I have a 4yr/48mo warranty that will protect me form the Boogie Man now


DH

propain

The boogie man is real. That warranty is the only thing that will keep it away. Maybe.... I never trust after market warranties. If your planning on tracking it you can bet it wont hold up if it blows up on the track.

Dirty Howie

I appreciate your concern but I have full confidence in the relationship my dealer has with V1 as well as my relationship with the dealer. This warranty will treat any LS7 failure the same as GMPP. I have seen GM communications via email from the highest level of management that GM recognizes these cars are tracked and the motors will be covered.


DH