telly444

so are the intake valves a concern as much as the exhaust?

ctsv510

Year and mileage?

American Heritage

2009
4,000 miles, totally stock, brand new car.

ctsv510

Wow, once again clearly a factory defect and an example of why every car should be checked regardless of mileage.

propain

Keep up the good work inspecting these cars and to CTSV keeping this thread up to date for awareness.

Whis9

good information

conner.mcgrath

we need ls7 valve guide wrist bands ...... and they should be brown bc this is ********

American Heritage

Posting per/customers Request (CF Handle: Mike Hoppe)
2008 C6z06
11,000 miles (100% stock)
GMPP warranty

Raw Wiggle test measurements (actual dial bore/mic is roughly half of wiggle test measurement/raw measurement).
#2 exh:.008"
#2 Int: .0115"
#4 exh: .0085"
#4 Int: .007"
#6 exh: .007"
#6 int: .005"
#8 exh: .008"
#8 int: .010"

#1 exh: .006"
#1 int: .0075"
#3 exh: .008"
#3 int: .010"
#5 exh: .008"
#5 int: .009"
#7 exh: .007"
#7 int: .0095"

ctsv510

Yikes! Intake worse than exhaust with only 11k miles. Thanks Kohle

Vette @ 71

To what do you credit the intakes for being worse than exhausts. We have been increasing seeing this. Seems to rule out EGTemp as a significant factor for guide wear, as one of our major head builder has suggested as a factor for exhaust guide wear..

Maligator

Ah, wonderful, it just keeps getting better, and better and better.................

timafey

Add me up to the list. Had my heads pulled and sure enough really bad guide wear, car just hit 20k 2008 bone stock.

ctsv510

added

john512

So from this thread this is all I saw as far as serial#s, etc:

2006 - F3220771
2006 - G0552126
2009 - I3532011
2011 - A1751270

2006 - 0602610
2006 - 1010508
2009 - 2211812
2011 - 2705909

Can we get more numbers added to this list to find any discernible patterns?

mygiftmycurse

2008 with 22,800 miles. I/H/C added by the previous owner around 16,000 miles. Street driven and some drag strip passes by the previous owner. Upgraded springs but stock heads besides that.

I sent my heads to American Heritage and I received an email with the following measurements. According to him, these are raw wiggle test numbers.

#1 Int: .021"
#1 Exh: .019"
#3 Int: .0145"
#3 Exh: .0125"
#5 Int: .013"
#5 Exh: .010"
#7 Int: .0135"
#7 Exh: .011"


#2 Int: .014"
#2 Exh: .013"
#4 Int: .015"
#4 Exh: .014"
#6 Int: .0145"
#6 Exh: .013"
#8 Int: .0205"
#8 Exh: .015"

roughrider1

This has probably already been considered, but could it simply be oil starvation, or maybe cars being thrashed from stone cold, or maybe over-revved on downshifts???

American Heritage

Ahhh.... there are a lot of thread on this with lots of varying opinions (even from expert/professional to expert/professional. This is the registry for out of spec guides. The search will bring up lots of other "discussion" type threads.

stefuel

Here and other places there are so many posts and threads to read on the subject that it is just staggering. My take on what I've read does not point to the valves themselves as the problem. Then you get to the worn guides. I find it hard to believe that they were loose at assembly so something putting to much sideways stress on the valve stem seems like a likely suspect. What would/could cause this sideways stress? Is it the alignment of the valve stem to rocker centerline? (rocker pushing it to the side as well as down). Is it the alignment of the centerline of the valve stem different then that of the valve seat? (valve closes and pushes slightly to the side). That seems a likely suspect. How many times can you bend metal before fatigue takes it's toll. I have read that there was a defect at some point in machining. I can see how that could happen IF the guides and seats were machined with two seporate processes but from a cost standpoint it does not make sense to do two processes. I do have some machinist experiance and if I were doing a raw casting it would be with tooling that cut the land for the valve seat AND drilled the hole for the guide in one pass.

I'm still looking for my Z06 to buy. When I find it, I will drive it home. It won't go any further then that without the "wiggle" test. If it fails, I will take it apart and I will figure it out.

ITCH

I just received my test results from Kohle at American Heritage Performance.
2007-Z06 24,230 km or 15,144 miles car completely 100% stock.I've owned this car since it's new.This car has only been street driven,and not hard.

#1 Int: .020"
#1 Exh: .0155"

#3 Int: .0185"
#3 Exh: .0125"

#5 Int: .0175"
#5 Exh: .010"

#7 Int: .021"
#7 Exh: .0165"

#2 Int: .0205"
#2 Exh: .016"

#4 Int: .0175"
#4 Exh: .0155"

#6 Int: .020"
#6 Exh: .016"

#8 Int: .0195"
#8 Exh: .016"

ctsv510

Added. Wow those are bad.