Coach62

One thing we (well most of us) know for sure is that the problem isn't hollow stem sodium filled valves. These have been used for DECADES, and were bulletproof in the LS6.

I do think the Ferrea may be a better valve choice, but they are very new and I didn't want to be the guinea pig.

I think there are 2 important differences with the Ferrea valve. I personally spoke to their engineer so I know this to be true.
1. it's thicker and more heavy duty, I suspect it won't have the valve bounce issue but we'll know soon enough. They claim the sodium isn't necessary, I'd prefer to have it but they were firm it's not necessary and they've been building this STYLE of valve for many years, just the LS7 valve is fairly new.
2. The weld on the OWM LS7 valve is low, near the valve head. Ferrea puts their weld up higher on the valve stem, they say this places the weld inside the guide reducing side load on the weld. I do think this is an important improvement.

My only concern is whether the lack of sodium will cause a problem. Ferrea is firm that it is not needed.

I do believe that Ferrea should be approached about kicking in some money. If properly handled, and allowing them to send it directly to Katech, I think they could be persuaded.

Oh - Ferrea was also clear that their solid SS valves were intended for turbo applications, not for the N/A LS7 operating and high RPMs.

Vette_DD

Stay on topic or stay out of the thread. If you have a post missing, it's because you forgot to do that.

http://forums.corvetteforum.com/foru...hijacking.html

'06 Quicksilver Z06

Taking into account that you say that you "personally spoke to their engineer so I know this to be true", regarding Ferrea, with regard to your item #2, according to the information posted by Hib Halverson in his conversation with his source whom he identifies as a GM engineer who "did most of the valve train development" and whom he interviewed for his article, it appears that your item #2 at least, is false.

nuck

Fixed I have to say that as more information becomes available, the PM guide option with solid valves, at least with the stock cam, gives me a lot of confidence in a reliable fix. If the bronze guides used by GM could be "off spec", and the stock exhausts themselves are not uniform along with inconsistent machining this would fit with the failure frequency and the fact that many stock setups have been beat on for expended use with zero issues. There may need to be multiple factors lined up to cause many of the failures. I am not in the bronze guide camp as far as repair methods go, but given that a fix with these wouldn't be from the OEM batch and the machining would be fresh this should also be completely reliable so long as there is no defect in the exhaust valve (which per the excellent post by American Heritage may be a concern). So sodium filled exhaust valves are not the problem,maybe just those particular sodium filled valves.

'06 Quicksilver Z06

To your first part in bold above, GM does not use bronze guides in LS7 heads.

To your second part in bold, the fact that so many cars have been built with the prior version of the sodium filled valves where inconsistent wall thickness has been discovered (and not just by AH either) is one big problem.

Over 20,000 cars may have been built with those pre marked valves.

propain

Thanks for the input AH. A very compelling argument backed up by actual data and research. A breath of fresh air and very much appreciated around here.

Your tests on wall thickness is appreciated as well and gives more food for thought on the use of the new OEM valves with the new part numbers if they were to be used. I wonder if GM thought the valves were the issue before discovering the machining issues out of their supplier and this was the reason they beefed up the valve wall thickness.


Seeing how quoting HIB has become a trend around here I will also point to this:

http://forums.corvetteforum.com/1587449894-post5.html

Where he states:

With that and the recommendation of Katech who uses the OEM valves in race engines which are rigorously tested on the track without failure I will be sticking with OEM valves until I see some test data showing that the lack of sodium has no ill effects in terms of heat management. The PM guides from AH seem like the way to go as well unless your going with a roller rocker.

40YRW8

Just a couple of things to think about. The wall thickness of the stems is rifle drilled to spec. When you friction weld them together you will get a slightly thicker spot at the weld. This can measure as an inconsistent wall thickness. Instead of having "Thin" spots in the wall, what you have is a standard wall with a "Thick" spot. Ferrea says that you don't "Need" sodium in the stems. Keeping the exhaust valves and seats as cool as possible is necessary to mitigate detonation. That is very important in our high-compression, track-built engines. Is it necessary for a street engine? No. Is it necessary for running a 30 minute track session? I really think so. Lots of companies claim that things are not necessary mainly because they don't sell them and they don't want you to go somewhere else for your purchase. Katech, in my opinion, uses them because they are up to the job AND necessary. Believe me, GM wouldn't have spent the extra cost for sodium valves if THEY didn't think they were necessary. Solid stainless valves are heavy but strong and don't cool the valves well. Hollow stem stainless is lighter, not quite as strong but still doesn't cool well. Titanium is much lighter, very strong but it also doesn't cool well. The stock valve is pretty strong, pretty light and cools pretty well. Any of these valves will work because the advantages and disadvantages aren't all that big a deal. Just build your heads in conjunction with what you are using. After reading about 500 posts about the valve issue even I was getting paranoid about the valves in my '07. I got over it soon enough and have 80,000 miles on my baby. Peace of mind may be way more important to an owner than the technical differences between brands or types of valves.
Gary

'06 Quicksilver Z06

Very well put.

American Heritage

We have spoken to Ferrea extensively about the F2042P valve.
Ferrea says that they believe the alloy used in the F2042P valve is better at transferring heat than the ss alloy used in the stock LS7 exhaust valve. They feel the F2042P hollow exhaust valve is better suited for the LS7 than the stock GM spec sodium filled LS7 exhaust valve.
We also spoke to Ferrea at Sima this past year and they were more than happy to discuss their dislike for the specs given for the stock GM LS7 exhaust valve.

Dirty Howie

So there you have it. Once again the experts can't agree

So who's engineers do you want to believe, Ferrea or GM !!!


DH

Mark2009

Since the GM engineers have made no comments or analysis regarding the Ferrea valve, your post is misleading. For all you know they may agree with Ferrea.

It is better to discuss facts, rather than create them -- or controversy -- out of thin air.


.

propain

GM hasn't made any statement on this. Their change in part number and what was observed to be a thicker wall might say something however.

Regardless of course Ferrea is going to say their valve is better. They sell valves and want the business. Ferrea saying "Our is better" really means nothing without something to back it up as they are of course biased.

Given both of those facts I would still stick with the OEM valve since it has seen a lot more action in the LS7 post fix without any issues or failures. While the Ferrea Hollow valves have been in use for a long time they do not share the same amount of history in the LS7 as the OEM valve at this point.

I honestly find it hard to believe how their valve can handle heat better than a sodium filled valve however. But again, that's just my opinion based on nothing but "Hot Air"

Coach62

Thank you for posting that. It goes back to what I said earlier, you have a lot to offer the board.

However - I think both you and everyone else understood that by saying I spoke to the Ferrea engineer and know this to be true, I simply meant it's first hand info, not hearsay. I've never claimed to be an expert on the subject and I'm keeping an open mind - I just want to know the truth, which is why I donated to the project to learn the truth.

To be fair, the engineer (I think his name was Scott if my memory is correct) did clearly say he wasn't really an expert on the OEM valve, but was of course an expert on his valve. Regardless, he did tell me the Ferrea weld was higher up the stem and inside the guide.

As to the conflicting information on the location of the OEM weld, I don't know what's what. Perhaps he misspoke, perhaps he was referring to the earlier production valves, I really don't know or care.

I do agree with American Heritage, that the Ferrea valve is likely the best overall choice. I ALMOST chose it, but it had just come out and virtually no one had used them yet.

I'm curious as to get a 3rd party opinion about the lack of sodium. Maybe American Heritage would have an opinion.

[Cerberus]

American Heritage, do you have any documents, photos, polished cross sections, surface finish reports, and hardness tests to go along with your data? I would be interested in seeing it all. It is very frustrating when stuff like this information is not posted online except by word of mouth. No offense to you or anyone else at all, but I really like to dig in and read the report, test parameters and the set up of things.

All this stuff being talked about can be tested. Why doesn't anyone do the tests? More importantly why doesn't anyone release this information? Real data published in a meaningful way is a lot better marketing then no data.

Heat transfer can be calculated, and while it is my my field of expertise, I would bet a hollow valve with a conductive filler would transfer heat better than a plain hollow valve and air. The thermal conductivity of sodium metal is around 77 BTUs/(hr *F ft) and stainless steel is between 4-26. Pretty huge difference.

If the heads of a used motor were CMM measured you could get the direction the alignment was out (if any), the shape of the bore of the guide which can tell you how it is wearing, is the rocker putting a lot of side load on it, etc.

'06 Quicksilver Z06

I would have considered this valve had it been available two years ago when I had my own heads done.

Like you and others though, were I doing it over again today, my concern with it would be that while this type of valve has been offered by Ferrea in the past for other applications, it hasn't been in use in the 427 cu in 505hp LS7 for very long at all.

As far as their alloy transferring heat as good or better than the stock sodium filled valve, you never know when claims like that are made by a company selling whatever it is they sell, be it valves or anything else.

About the only way I can think of to substantiate that claim to where I, as a consumer would consider it, would be through independent testing of both, by a neutral investigator to see which one transferred heat best.

The remarks by 40YRW8 in the regard of heat management and potential detonation are concerning when I look over some of the history of this issue.

For a while, many thought that some of these valve failures were actually piston failures which had been misidentified as valve failures.

So when he brings up detonation in his post as a concern for poor heat transfer, it makes me think back to some of the instances early on, where some of the valve failures may have been misidentified piston failures.

His comments on detonation also make me think of cracked sleeves, and ruined engine blocks, in cars which in some instances won't die right away. Indeed, might be running find. You'll just find antifreeze in their next UOA.

So as I look at the whole matter, if I were making a selection between any of the three valves today, they all seem to have their drawbacks.

It's almost a pick your poison/how much risk do you want to take/ exactly which risk do you want to take, type situation.

'06 Quicksilver Z06

As do I, whenever possible and those items which you point to are readily available.

[Cerberus]

No offense, but what are you trying to say? I have read everything you have written and I can not tell what you are trying to say here? Do you have data to add or are you just trying to say you wish there was more out there?

'06 Quicksilver Z06

None taken, as what I wrote was cryptic and amounted to walking on eggshells so as not to open any wounds about my critique of prior research done in here and the materials, methods, financing and neutrality, or lack therof associated with it.

Or what I consider and interpret to be, "the setup of things", to borrow your phrase, whenever I look at data or results.

I'm saying that I wish there was more data out there.

However I qualify that by adding that I am particular about whom the data comes from and when it comes from non neutral parties, I tend to give it less consideration.

To me, "data" which comes from a source with a vested interest in outcomes is worth less. Especially when there is no similar data showing similar results from any other investigators.

I'll look at it. But I look at it knowing that it's not a neutral source from where it comes.

If you've read everything that I have had to say on this matter, well then you know of my comments on the findings of 240sx2jz, an average forum member, with no known ties to GM or any valve vendor, and whose findings on inconsistent wall thickness, are "consistent" with those reported by AH.

The reason I am more prone to accept Kohle's reports of varied wall stem thickness, is because his results seem to be consistent with the findings of 240sx2jz.

But yes, it would be nice if others with no dog in the fight were to offer up their findings after the same type evaluations.

Dirty Howie

I don't disagree with anything you have posted above.

I'm sure GM had the option of NOT filling the valve with sodium. So despite what others may say there is obviously a difference of opinion amongst the engineers. And I don't understand why some (not you) find this so astonishing. It happens in every professional field. As in the past its going to come down to who do you trust and what makes sense in your mind to address your particular needs. I think I have said this before


DH

Coach62

The Ferrea engineer I spoke to did have an explanation. I don't recall the details so I won't go there right now. If I get the time I'll try to call them and see if I can get something - in writing if possible or I can just take notes.

As you said, GM apparently felt it was necessary or they wouldn't have spent the extra $$$.

One thing I do recall is Ferrea did say they've been running their hollow stem valves for many years without sodium - mostly in race applications and they don't feel it's necessary. I just don't recall the details of the explanation.