Turbotank

Here's a Vid of number 6 cyl on my 69k mile 06.. it's measured with the valve off the seat. Looks like I'm out of spec.

https://www.youtube.com/watch?v=nrfXE1FdKIQ&feature=youtube_gdat a_player

Bill Dearborn

Hard to see anything. Gauge is barely visible. I can just barely make out the needle moving.

By the way you can include the video in your post by Going Advanced, clicking on the YT icon and then pasting the youtube link between the YTs.

Bill

propain

ctsv510

Looks like .011-.012 on the wiggle or .0055-.0060 actual clearance. Not the worst after 69k miles but definitely out of spec. Good thing you did the test.

Now what?

"NO SHOW"

This is the first of three we are checking.

The other two are 06's as well, 29k and 14k miles on the clocks.

Turbotank

Here's the second car...
https://www.youtube.com/watch?v=PN21MHGVZaQ&feature=youtube_gdat a_player

Mine is the 69k mile car and it'll be getting a set of heads... not even putting it back together after the test. Going to pull them off the car and get them out And built

Mark2009

That one looks like .007 wiggle, or about .0035 clearance. Borderline... I'd check 'em all if the decision has not already been made to pull 'em off.


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rockinSeat

So .06 after 69k miles, is that from wear and tear, or the factory machining problem?

Mark2009

From my interpretation of what has been posted by those in the cylinder head business, .006 guide clearance is excessive for 69K miles in an LS engine.

Undy

At 88K miles all my exhaust guides were well within specs, per WCCH's measurements.

ctsv510

Turbotank

No reason to risk we we have already decided to pull his, mine and noshows... nothing like having to do three sets of heads...

Mark2009

A head pulling party!

Yeah, at .0035 it's likely just a matter of time before they get worse. Might as well get it over with, especially if the car is going to be run hard.

ctsv510

What were the results from "No Show" ?

Turbotank

We haven't checked his yet but he doesn't want to be the only one left stock so we are just going to do all three together. We will pull his this week and check them on the bench.

For ***** and giggles I grabbed an old 98 150k+ ls1 head and a 15K mile LS3 head I had lying around and the junk ls1 had.001 and the LS3 had .002....ls7 heads FTL..

"NO SHOW"

We haven't checked mine yet, Turbotank or myself will post the results after we check them.

I have already decided to pull the heads and not chance it.

Mark2009

Not surprising but thanks for taking the time to check

rockinSeat

Agreed it is excessive, I guess I'm really curious if lasting till 69k with the factory defect was what happened or was there no manufacturing defect and the guide wear occurred over time? I think that both cases are occurring - and the 69k mile car would be one example. If the car had the factory defect, I would have thought it would have dropped a valve or have much worse wear.

Mark2009

If the problem is sloppy machining, then it is quite possibly a matter of degree. Some heads could be worse than others. If you've followed this issue, then you'll recall that one owner had a problem with an intake valve guide at 400 miles.

Alternatively, if the problem is a matter of 'core shift' as a new head heat cycles over time, then that could also be a matter of degree. Some heads could 'shift' more than others.

If the source of the issue is machining or core shift, there is nothing particularly mysterious about some heads being good, some heads being slightly bad, and some heads being very bad. But based upon what has been said by those with a lot of experience with LS heads, we should not be seeing any significant guide wear in the LS7 heads. Something is wrong. Why, we do not exactly know.

As far as dropping valves go, it seems that the OEM valves are a bit tougher than some make them out to be. Of course, given enough abuse, they will break.

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Dirty Howie

Not as tough as solid SS. Thats why those of us that have put them in our cars have a better chance of surviving GM's spec. In fact I wonder what GM's spec would be if they had put SS valves in the car?


DH