Gearpuller

Add me to the list also.
2010, 21,500 miles, produce 12/09
No mods done....yet.

I bought this car 2 weeks ago knowing full well that I could have this problem. I am the 3rd owner. I put 500 lucky miles on it in 2 weeks.
Just got back from my shop where I keep it and my drag car.
Preformed the wiggle test (only on cly. #2 ex.) before I even set up the dial indicator I knew I was screwed.

.024 (yes you read that right, checked it 3 times).

I have replaced valves in cly. heads before where they only needed to be lapped in, built many of small and big block Chevy's (very high performance),I work on both diesel and gas engines in aerial lifts and telehandlers (Genie and JLG's) and I have never seen this kind of wear.

I am not going to take it to any dealer to get it fixed, if they cant do it right the first time how can I ever trust that the repair will be right (besides I don't like anybody else working on my car).

After I remove the heads I will come back and give the full read out of all clearances.

And let the mods began. Good time to put in cam and headers.

American Heritage

This is a data thread

It is important to the corvette community that this thread remain data driven (as opposed to opinion/advertising driven). No disrespect intended, just want to see this thread stay data only and not get side tracked.

Gearpuller

I will probably use Texas Speed, 1 hour drive away from me. $1350 for guides, new s/s ex. valves, new .650 springs and retainers and porting work.
May use their LS7R cam.

Dirty Howie

Sounds good. Nice to have a good shop so close


DH

wjnjr

Waco to Lubbock in 1 hour??!!!

Gearpuller

Texas Speed has moved. They are just north of Georgetown along I-35

Gearpuller

Results are in. Not what I expected. I wrote in my first reply that it was #2 exhaust was out of specs, end up being the #2 intake.

Cly #1 in. .033
ex. .003

Cly #2 in. .024
ex. .005

Cly #3 in. .026
ex. .003

Cly #4 in. .019
ex. .005

Cly #5 in. .031
ex. .003

Cly #6 in. .016
ex. .004

Cly #7 in. .013
ex. .002

Cly #8 in. .018
ex. .0025
So my exhaust were pretty much in specs and intakes were shot.

Mark2009

Seems to be an interesting trend on the 'newer' cars with the exhausts mostly okay but the intakes whacked.

I presume those are actual wiggle numbers and not the calculated clearance?

wjnjr

How do the intake stems look/measure?

MTIRC6Z

Yeah but still a proper 'fix' has to involve getting those JUNK stock exhaust valves out of there because we all know completely worn guides have nothing to do with why the stock exhaust valves fail...at least that's STILL the gospel according to du quick

Cheers, Paul.

Gearpuller

These were wiggle numbers with the valve 1/2 in. down.

Intake valve stem measures .313 where there is no wear to .3129 where the stem was inside the guide.
I can live with .0001 wear.

Zeaux6504

2008 Z06
20,000 miles, street use, never tracked
Wiggle test performed by American Heritage

Needless to say, the heads will be reworked by AH.

The following is my wiggle test results.

#1 int: .010"
#1 exh: .005"

#3 int: .0125"
#3 exh: .007"

#5 int: .0135"
#5 exh: .007"

#7 int: .012"
#7 exh: .0075"

#2 int: .011"
#2 exh: .0075"

#4 int: .0125"
#4 exh: .0065"

#6 int: .010"
#6 exh: .0055"

#8 int: .011"
#8 exh: .007"

Random84

Interesting that in both cases the intake valves are all well on their way out, yet the exhaust - with the now notoriously inadequate sodium-filled hollow valves - are in essence still within specification. Must not be purely a heat transfer / "bad valve causing wear" issue? Pretty wild, really.

Perhaps the guides/install was fubar'd from the get-go?

Glad you caught it though!!!

Norm_427

I thought it was interesting to do percentages of those who posted out of spec divided by the production numbers. Numbers are taken from Post #1.


THE OUT OF SPEC LIST: (stock powdered metal guides)

2006: 43 of 6272 produced (20.5% of production) = 0.63%
2007: 46 of 8159 produced (26.7% of production) = 0.56%
2008: 42 of 7731 produced (25.3% of production) = 0.54%
2009: 25 of 3461 produced (11.3% of production) = 0.72%
2010: 5 of 518 produced (1.70% of production) = 0.97%
2011: 5 of 904 produced (3.00% of production) = 0.55%
2012: 2 of 478 produced (1.60% of production) = 0.42%
2013: 1 of 471 produced (1.50% of production) = 0.21%
427: 0 of 2552 produced (8.40% of production) = 0.00%

.

EWK

2009 Z06
7,666 Miles
Street use, Never tracked
Heads reworked by Katech Performance
Valve Guide Clearances done by WCCH

#1 - Intake = .0057
#1 - Exhaust = .0041

#2 - Intake = .0093
#2 - Exhaust = .0039

#3 - Intake = .0052
#3 - Exhaust = .0038

#4 - Intake= .0097
#4 - Exhaust = .0037

#5 - Intake = .0071
#5 - Exhaust = .0042

#6 - Intake = .0106
#6 - Exhaust = .0052

#7 - Intake = .0065
#7 - Intake = .0044

#8 – Intake = N/R [Too large for gauge]
#8 – Exhaust = .0038

Gizmo5

I just had mine gauged and Kohle from AHP said they were all in spec with 47k miles. I'll ask him what the numbers where on the measurements and report back.

Vette @ 71

This the out of spec thread, add results to the in-spec thread.

GeneSch

2006, All stock. Some track days but not abused. 10,300 miles.

Wiggle
tested your bank 1 head (driver side).
results are as follows:
#1 Exh: .0125"#1 Int:
.010"
#3 Exh: .013"#3 Int:
.009"
#5 Exh: .014"#5 Int:
.010"
#7 Exh: .013"#7 Int:
.008"
The are the raw wiggle test measurements.
The actual measurement is roughly half of the wiggle test
measurement.

3 Z06ZR1

Yikes 45k and no issues but pulling heads and adding (waiting to hear on 2013 heads stock)

Z06_1

I guess I get to be added twice.. I bought a set of used heads (off of a 2013 427 vert) with a whooping 4k miles (yes 4k), and low and behold, exhausts are fine, but all the intakes are out..

Thought I'd save some cash, slap the roller rockers on them and call it a day.. Not a chance, they will need to be reworked.. At least I won't be down for more than a weekend.

Trust me my friends, this is geometry / design / factory tolerances problem, not a "you have bad luck" problem..