MTPZ06

No amount of data/statistics is going to get you the answer you're looking for. I assume you're either looking to buy, or have just purchased a C6Z? The only way to know if you own a car that's adversely affected, is to inspect your own two cylinder heads. Don't get caught up in a numbers game, and try to justify why you should or shouldn't have to fix something that hasn't even been inspected yet...and its a simple process to do so.

Inspect your car, examine the results, take action based on those results. That's the best advice I can give you. Lots of good options for resolving valvetrain issues that plague these cars for very little money when compared to cost of ownership (clutch, tires, brakes, etc.). By no means should this issue deter you from purchasing one of these cars if its really what you want.

bd4airman11

.....on the money....!!!

Triple88a

is it possible to check the valves without a compressor?

bd4airman11

If you take both rockers off one cylinder like #1, then perhaps #4 and if you look very closely at the part of the valve stem you can see, just push, or rock the top of the spring retainer or top of the valve intake to exhaust or exhaust to intake and look and feel for movement......It is NOT as good as taking it apart by any stretch.... but if you feel movement it would be prudent to take it to someone for the real check out......Mine were so bad after I did the complete check and teardown (spring off) with compressed air, I found I could tell just by pushing on the top and watching very closely....The stem seal will just push up and you can see the stem move in the guide with good lighting.....just push with your hand. Needless to say I completely redid my heads......Just doing this is a good start to seeing how much where you may or may not have....It's a start.....good luck.....

Tipp44

Allow me to post the results of my 'wiggle test', performed by Kohle at AHP.

2006 Z06 that I purchased after it had the motor replaced by GM. Current engine had approximately 5k miles on it. I had the initial check of the heads done at LG while they were still in Plano. The findings were poor, so the heads were taken off and sent to Kohle.

Results:
#1 int .020" #2 int .013"
#1 exh .007" #2 exh .007"
#3 int .015" #4 int .015"
#3 exh .0075" #4 exh .006"
#5 int .012" #6 int .017"
#5 exh .007" #6 exh .0065"
#7 int .018" #8 int .019"
#7 exh .009" #8 exh .0065"

Replaced with:
AHP Package 4
Ported heads
BTR dual springs with titanium retainers
BTR stage 3 cam

This was all done a while back and I recently sold the car, so if you've purchased a velocity yellow Z06 in the DFW area in the last few months feel free to contact me. I have some invoices for it and such.

RamAir972003

Let's update any reworked heads after done valve guides

stew1100

Vengeance Racing in Atlanta did mine

and did a great job. Super bunch of folks.

my Z is still kicking azz 30,000 miles later

Sotel102

AHP Package 4 heads at roughly ~9k miles on the '07 C6Z06 last year.

Still going strong...

Formula8

American Heritage Performance did the heads on my 2007. Replaced the Ti intake valves with OEM replacements and Ferrera Exhausts. PM guides, CHE trunions and Johnson lifters. Everything else is stock.

The heads were done at 29,000 and I am now at 31,000. I run 0w-40 mobile 1 and deleted the oil cooler. So far, so good and the valve train is much quieter.

JohnRR

I deleted my oil cooler a couple of years ago. The oil heats up much quicker and has never gone above 215 degrees.

El Paso Vette

Cordes Perfomance Racing (Phoenix)

Mileage 62,000

Material WCCH Heads

Parts Custom Tune

Car used for....In town and long drives no track

Cam OEM

Follow up disassembly and data. +65 HP on Dyno

Oil change intervals...4-6,000 miles

Type of oil Mobil 1 (OEM)

RamAir972003

Ttt

Uncle Meat

At 54K miles on my stock, never tracked car, Katech measurements were as follows:


U.M.

AzDave47

Interesting that Katech uses .0025 - .0026 as the clearance limit as all others have reported GM says .0037.

Katech_Zach

Our specs are the same as GM. The production tolerance is .001-.0024" on the intake and .001-.0026" on the exhaust. The service limit is .0037" on the intake and exhaust.

AzDave47

Thanks for that detailed clarification, Jason.

Dave