BigVette427

Overall a good article on the LS7 valve guide subject. They could have thrown GM under the bus a little more than they did, but I can understand why they may not have wanted to belabor that point. Sad thing is the fact remains that if you have an LS7 (Z06 or a Z/28) you need to at least have the motor inspected.

http://read.uberflip.com/i/834132-july-17/77

Tigershark3

Thanks for the info. Katech did my heads last summer. Very pleased with the result. Out of 16 valves all but 2 or 3 were out of spec.

Dan_the_C5_Man

Unfortunately, this article just tossed more gasoline on the ever-raging VG tire fire..

The real value of the article is the very last few sentences - posting the quote from GM about 100% inspections (sic) will only provide cannon fodder for the valve guide denier community...

We can only hope the people reading this article will be smarter than the average bear, read between the lines, safely ignore most of it and just focus on the last two sentences.

Mr. Jean

So I'm sure this means all the replacement heads their sending out now are fixed, right? Got mine just awhile back, sure hope so.

UH-60DRIVER

Replacement heads their sending out? How do I get a set?

z06vettewannabe

No mention of Z/28.....only C6 Z06. Haven't seen any issues at all on the Z/28 forum.

rockinSeat

No, on the upper right corner of the first page, katech verified the problem applies to all LS7, 2006-present. They should have marked that summary section more clearly as "gm issued statement".

Anyway guess we have multiple choices for repair parts now. Which is better?

MikeOC

No, brand new GM heads have been found to be out of spec.

If we limit ourselves to what's referenced and recommended in the article, you need to adresss valve coatings or valves entirely, guides, guide concentricity, and valve seating.

Mr. Jean

I got mine during a GMPP replacement when they failed spec, during a teardown for failing cam and lifters replacement.

As mentioned above, mine was a GMPP deal, so I didn't have this option at the time. Still a year plus left on my GMPP, so we'll see how things look next year, when we have another wiggle test..

I was being a bit sarcastic in my earlier question.

stefuel

This is America right? We can still have a opinion right. Well here's mine. LS7 theory GOOD. Implementation not so good. Why do you suppose GM went to a larger platform in the 60's for the 427 AKA big block? Why didn't they just stuff a hundred extra cubes in a 327 small block? The very first time I saw those offset rockers the hair stood up on the back of my neck. A bigger block to allow for thicker sleeves and straighten out the geometry and I'd bet the farm it would be reliable
Someone back then knew you couldn't stuff 3 pounds of $hit in a 2 pound bag. Rant off

Tech

Based upon the dates that Katech provided in that story, they didn't really address whether they felt GM's claim of it being a "small batch" in a certain production range was correct.

Nowanker

Wow. What a highly informative article!
Oh, right. Sarcasm doesn't come off well in print. Sorry.

I do know of Katech's revered status, not just here, but industry wide...
But when I read the article, it reminded me A LOT of Steve Dinan.
But seriously Big vette, thank you for the link.

Katech_Zach

On the third page of the article there is a gray text box that includes GM's statement of 2009-2011 vehicles. On page 2 of the article under the heading titled "MORE THAN EXPECTED" we stated: "Katech's independent research has not limited the issue to 2008-'11 models, but rather all LS7s and LS9s 2006-present."

Landru

Sounds logical, but I'd a pal w/ a '68 L-88.
His motor sucked a valve not once but twice, was w/ him 2nd time.
A valve spring would break releasing vale to drop-in cylinder.
Damned good thing this came from a well endowed family.
Today aftermarket retainers are available for L-88s to prevent this happening, hold broken spring retaining lifter.
Salient point being some Chevy BBs had issues, severe issues and L-88 was one.

Technology's responsible for eliminating the need for a 550# block made from cast iron. Totally unnecessary, today.

Weight savings alone made LS7 the performer it is and always will be.
IIRC fully dressed a LS7 weighs ~300#s. Not bad for 505 HP.

z06vettewannabe

What surprised me was the article says it also affects LS9 motors......had never heard that before....

Gary '09 C6

here you go...check the attachment list.


https://www.corvetteforum.com/forums...on-the-cf.html

rockinSeat

I caught that too. Thanks for the article and helping out LS7/LS9 owners, Jason, Katech.

mirage2991

soooo how much is a set of Street LS9 heads with those fixes? just curious....

08mojo

Someone correct me if I'm wrong, but I thought Katech had their head machine work done by WCCH. Does Katech do the work in-house?

mirage2991

when you look at whcc website, only their ls7 heads are mchined for guides and seats. the ls9 just get the cnc porting.
This article says that even if you get new ls7-9 heads from gmpp you will still have the same issue... kinda bummer because you can get cnc heads for 900 a pop complete from them (or via jegs/summit)