JW7676

Yes SS valves.

No4Play

I've been running SS exhaust valves and factory intake valves with bronze guides for 15000 HARD miles. Not 1 issue yet. Since I have had the car I have only used amsoil 10W30 with zddp. I have very extreme ported and polished non-milled heads, 246/256 @ .650 lift cam and full bolt ons; I beat the crap out of my car and the only issue I have had is the original factory water pump had a small leak at the seal. Otherwise, runs like a champ.

ctsv510

Do you keep track of who on this list has a wiggle test done at any point after changing valves? Or does no one really do wiggle tests once they have changed valves/guides?

'06 Quicksilver Z06

If there are those who still want to do them, then they're free to do so.

In light of the dearth of engine failures due to valve breakage incidents amongst members on this listing, it is hardly worth my time to track such.

And without there being any documented and established correlation between a "passed" wiggle test, and stock hollow stemmed exhaust valve reliability and dependability, I tend to put less stock into a "wiggle test" as a reliable predictor of outcome.

In other words, no one has shown that guide wear was consistently present when a stock exhaust valve failed in here.

In large part because stem to guide clearance is hardly ever measured neither before, nor after the catastrophic event.

As such, you show me a popped motor due to a dropped stock exhaust valve, and typically nobody knows what the "wiggle test" results were neither before, nor after, the mishap. But the assumption is made, that "Oh it dropped a valve, so the guides must have been worn."

Perhaps they were, perhaps there weren't. Since in the large majority of the failed stock exhaust valve cases I can find in here, nobody ever bothered to measure stem to guide clearance after the destruction, how would anyone know what it was when the failure occurred?

However, if you would like to do so, well then feel free.

I can get you started with the case of forum member Madsen, who had SS valves and apparently thought that he had bronze guides too, but discovered that he still had his stock powdered metal guides, on teardown following dropping a valve.

His stock powdered metal guides being used in his setup, were severely worn.

If you're going to do this, well then use bronze guides. Bronze guides have better wear characteristics than do the stock powdered metal guides.

Forum member 240sx2jz, after 25k miles, mild cam, found that all the guides in his reworked heads were in spec on wiggle test.

This in one of the earlier sets of their heads, during a time when they were starting with more stem to guide clearance than in currently redone heads.

If you would like to know any further information regarding wiggle tests for this segment of the forum, then feel free.

Good luck.

'06 Quicksilver Z06

I wanted to announce that I am going to be making a few changes to "The Registry".

We've topped over 300 cars belonging to forum members now, which represents around 1% of total Z06 and LS7 Vert production.

It may not sound like much, but when you take into consideration that the majority of LS7 owners are not on this forum to begin with, and also consider that not everyone who has gone this route is identified, or even a member of this forum, well then it is significant.

Furthermore, now that the Z06 and 427 Vert are out of production, this number figures to rise.

When I first started this, I didn't expect to find nearly this many owners who had proceeded along this path. I initially didn't expect to see it reach this many owners.

I don't have to tell you that what we are witnessing here, is unprecedented, and when it comes to a substitution for stock, you will be hard pressed to find anything like it in any other section of the Corvette Forum, unless you're talking about column lock disabling devices in the C5 section of the forum, skip shift disabling devices in the C5 and C6 sections of the forum, or mild to wild switches.

But arguably no other internal engine part change, is made with this kind of frequency, and more importantly, nor with this kind of success.

At any rate, I think that it is important to identify any new additions to the listing by model year.

Yes, often times this is indicated in the posting which states that non stock heads are being used.

However this is not always the case.

Thus I feel that to better serve the segment of forum membership, who is interested, with this listing, that the year model of the car be included along with the screen name of the owner.

So future additions to the listing, will include the year model of the car, along with the owner's screen name.

I wish the best for you all, irrespective as to if you agree with this method, and look forward to the next 97 members which will take the number to 400.

Good Luck and happy motoring.

Dirty Howie

Just amazing! Seems like it was 200 just a few weeks ago!!

Great work Ricky


DH

Frankie2blue

Talked to Lingenfelter today and they don't believe that Stainless /bronze is the way to go. They use P/M guides and OEM valves and they say that it is really a tolerance issue of the guides, and that they have had ZO6's in there with as low as 12 miles from the factory and found guides out of spec. He said they have not had a failure yet rebuilding the stock style setup.
I for one have not done anything yet because I really want to keep the motor as it was designed if and when I do something even though it seems to go against popular opinion around here. Hoping for more info on this route.

'06 Quicksilver Z06

Wow, 12 miles. That is incredible

Also, you might want to take a look at the following thread Frankie.

Good luck.

http://forums.corvetteforum.com/c6-z...ust-valve.html

Mark2009

We now return you to your regularly scheduled propaganda

Frankie2blue

Actually he said they tore one down with only 8 miles never driven except off the line and 5 guides were out by quite a bit. But he insists that the valves are not the problem and they have torn down heads that they re-did a while back and found no issues still using the PM guides and stock valves, which I found interesting.

propain

Lingenfelter is another big company I wouldn't disagree with. Thanks for the update.

12 miles? How is that even possible. Just goes to show this isn't any kind of wear issue or heat issue or bad valve issue. This is a defect coming out of the factory from their head supplier. Wow... 12 miles...

ClarksZ06

I find this very interesting too. Except how do you explain some Z's going a few thousand miles with drastically out of spec guides, some going ~50k miles with slightly out of spec guides, some that have widely out of spec guides with ~50k mikes, and the few that have gone 100k miles virtually no wear ?
You think the guides originally installed from the factory come in all different bore sizes ?? Surely that's not possible.

propain

I think it goes back to the statement:

How badly they come out of the heads supplier could be how severe the guides will wear. Use also plays a huge roll. Its no coincidence that the majority of failures are from tracked and or modded Z06's. How its used will either delay or accelerate a badly machined guide. Who knows how long cars with recorded valve guide wear would have went if nothing was done to them. Maybe 100K miles depending on use. Again, majority of failures are track or modded. Many are lightly driven but second and third owner cars with no previous knowledge of how they were driven.

'06 Quicksilver Z06

Very interesting Frankie. Very interesting indeed.

One of the reasons why I'm so proud of this thread, is because of its effectiveness in disseminating new information, and in an unbiased manner such as that to which you point.

With QC issues to a point to where you indicate in that post, it definitely tells me that the people who sounded the warning bell about this matter early on were justified in doing so.

A car with out of spec guides inside of 8 miles, is a huge concern.

If the guides were already out of spec at that point, well then how far would it have gone before disasaster struck?

Probably not far.

LFZ

Just because a Z goes 100k miles, doesn't mean it doesn't have guide wear. Who do you know that has a 100k mile Z with inspected guides? Just because it has guide wear, doesn't mean it's going to drop a valve right off the bat. You see why this is so bizarre....

How about that geometry theory?

ClarksZ06

I just meant that the few members here that have over 100k miles must have little to no guide wear issues to go that many miles without failure.
I've seen the steam gnawing on my sodium valves with guides that measured .0148. It was literally a short matter of time until the valve would of failed with only 9k miles on the motor.

propain

I don't believe those members have inspected for guide wear. At least not that I have seen. I would bet even if it went 100K miles it has guide wear. I bet out of spec too.

silvrhand

Add me to the list:

2008 Z06 40k miles:

- ss exhaust valves, bronze guides, ported/polished heads, new rocker bearings.
- done by england green in Houston

'06 Quicksilver Z06

Thanks Howie.

I'm really glad to see other forum vendors step up and accommodate our fellow forum members.

Alright silverhand. 2008 with 40K miles.

Welcome aboard.

There is always room for one more.

Dirty Howie

There is no doubt in my mind that you have single handedly saved many of our members from blowing up their motors and landing on that OTHER LIST (for which I am a member ). I don't think even your detractors would begrudge you this point


DH