rzmnco

I am currently having SS Exhaust valves and bronze guides installed now at Race Proven Motorsports.

'06 Quicksilver Z06

As per usual Rock, excellent information in both of your last posts, and why that commonly referred to article on spintron testing has to be taken in context.

Yes, they got valve bounce when they tested a 98g Inconel valve using PSI 1511 valve springs.

But now we at least have more clarification as to why.

The article does not show that the use of heavier solid stemmed stainless valves in these motors is necessarily a "bad" idea.

But rather what it does show, is that the use of heavier valves with that particular valve spring, in these engines, is a bad idea.

Rock36

Another interesting thing about the article, the article mentions the 402 ci engine power peaking at 6300 and then "taking a nosedive".

This makes me think, if a LS7 with SS valves was showing float and/or bounce we could potentially see some kind of similar "nosedive" due to the lack of pressure inside the cylinder.

I would be curious to see a dyno graph up to (or beyond) 7000rpm of a cammed LS7 with SS valves, and see if there is a similar "nosedive". The torque curve will be on a downward slope anyway because it will be past peak torque, but if there is a steep negative slope beyond 6500 rpm, that might be a hint that the valve train is stable or not.

Which, is an actual test we can do, since none of us have access to spintrons. I don't know if we have any such dyno graphs.

I'm just spit-balling there, because there could be other reasons for a steep drop off in power, like the intake manifold can't flow enough air at that speed or whatever.

2000FRCZ19

mine has dual springs and it didn't nose dive like the one in the article. yep dual springs and heavy valves are a bad idea. it will not rev to redline like it did stock anymore. it will blow up. I have heard it all but for some reason my cam grinder said it would be just fine with the springs they recommend and for some reason it actually works and has been for over a year. it puts out almost the same power as as it did on the original dyno. I have more power than stock. it revs fast and it hasn't blown up. do I still need a spintron test?

ramairws6

Trust me i have the same deal. My 8 different cams showed none of the so called "nose dives" with my ss vavles and double springs. We must have just got lucky

jbvaldez

SS Valves with Bronze guides. Work done at Dallas Performance.

RedZ4me

Any concerns from the slightly extra dual spring pressure as it affects the lifters - premature wear??

Mark2009

I see. Even though the link I provided talks about the progressive spring rate nature of beehive springs. Even though the vendor (Katech) lists two installed height spring pressures that indicates progressivity, not linearity. Oookay . . . .

Dirty Howie

I like the "0" horsepower loss


DH

Mark2009

We could. That would be a definite indicator of valvetrain instability. I don't think it would be the only indicator.

Again, I have never said that the changes proposed cannot be made to work, simply that a tested/validated system is being replaced with something that lacks the same level of testing/validation, and that the repeated arguments of it being better than a properly functioning OEM design are riddled with illogic, unfounded assumptions, and outright mis-interpretation of data (such as the linear/progressive spring rate discussion) -- all presented as so-called 'fact'.

MarkC

Quick and others, are there any examples of changing to SS exhaust values with bronze guides and you still have bad geometry? That would be a bummer!

Quick, I think you heads went from bad geometry to good after WCCH reworked them. Why?

Mark

'06 Quicksilver Z06

Is Chevy High Performance a professional peer reviewed journal, like JAMA or The Lancet?

You do realize that any of these articles being quoted, are not being quoted from peer reviewed scientific journals, are written for lay people, and may well have errors in them.

Furthermore, I wonder why you snipped out Rock's most important point

So in the context of the article from GM Hi-Tech Performance "Hydraulic Valvetrain Performance" which says:

"This article will specifically address one portion of the test to understand the effect of valve mass on valvetrain dynamics by testing a hollow exhaust valve against a solid Inconel valve on an LS7 valvetrain. We tested this because many people choose solid stainless steel or Inconel valves as an "improvement" over the factory stainless steel, sodium filled, hollow-stem valve."

The listed seat pressure of the PSI-LS 1511 valve spring is 120lbs @ 1.80".

The Katech catalog says the installed height for PSI-1511 springs on the LS7 is 1.85".

Which is taller than 1.80".

So whether or not seat pressures for the PSI-1511 are linear or progressive, at a 1.85" install height, it is expected that seat pressure will still be less than it would be a 1.80" spring height, which is known to be just 120lbs.

So if this was an LS7, like ours, that Katech tested for he article, and they were using the recommended spring heights for the LS7, which is 1.85", then the spring install height would have resulted in less spring pressure than 120lbs, whatever that number is.

So your point is moot.

Linear or progressive, it's still installed at a taller spring height if going by Katech's recommendation, and so whatever the seat pressure is, it can be expected to be less than 120lbs.

'06 Quicksilver Z06

Oh, here we go.

Why don't you quit pointing to that ONE article then in your attempts to bolster your position against their use?

So what? I could see if the "replacement" were not working. But so what if they have not been "tested/validated" using the same level of "testing/validation".

And why the selection of the term "validation" unless you are attempting to imply that any other setup is "without validation" and thus "invalid"?

And as far as "testing", spintron testing, who says that it is the only "valid" method of testing?

See my comments on your "linear vs progressive" argument.

The point is, you know damn well that the seat pressures of the springs at the install heights that they would have been, for the purposes of "testing/validation, are considerably lower than those used in for example MY setup, where I show the seat pressures, and mine are typical.

Anytime anyone in here quotes or references that ONE article again, you, anyone else, in an effort to discredit the use of stainless valves in these cars as a viable alternative to the use of the stock valves, and thus mislead this membership, this will be pointed out.

Mark2009

My point was:
And has been well made

Your repeated attempts to argue the obvious does not paper over the underlying errors in your argument.

'06 Quicksilver Z06

If you believe in this "geometry" "good juju vs bad juju" approach, then you have to accept a few things.

1. It is possible to go from good geometry to bad geometry by having head work done.

2. It is possible to go from bad juju to good juju by having head work done.

3. Apparently everybody who had "bad juju" and went to stainless valves, when they had their heads done, now has "good juju", as no stainless valve in here has failed, and no bad juju has been identified from the juju test after having been done. Even if they were known to have been afflicted by bad juju as their guides were originally shot in the first place. If your guides are shot, or were shot, well then the biggest reason for them having been shot, is bad juju. Bad juju is the leading cause of valve guide wear.

4. Having your heads done, but sticking with the stock exhaust valves, does not remove the bad juju if you had it before. As there are at least two cars in here, which had their heads done, but kept their stock exhaust valves, and promptly broke the stock valves.

Bad juju. Now some imply that the installation of "new guides" might cure bad juju. But they offer up no example demonstrating that it actually has.

4. In the cases of the cars which failed in here after having their heads done, but sticking with the stock exhaust valves, one can immediately think of two possibilities as to why that may have happened.

A. They started out with good juju, and when the heads were done, ended up with bad juju.

B. They started out with bad juju, and after they were done, still had bad juju. But apparently such a case of retaining bad juju after headwork and using stainless valves, is not in the annals of forum history......so it must have been bad luck, that they still had bad juju after the heads were done.

Now of course, the above is all said tongue in cheek, and is allegory.

But I don't for one minute believe that the guides wore out in my spare set of heads due to "bad geometry", and then after I sent them to WCCH to have them do the stage 2 port work, guides and valves, than now all of a sudden they have "good geometry".

Mark2009

Making stuff up doesn't help your argument either

'06 Quicksilver Z06

Point to the one belonging to a member in here which snapped off a valve head and had it fall into a combustion chamber like the stock ones have been known to do, again.

I didn't see it the first time you posted it.

'06 Quicksilver Z06

I put you both on the listing.

Sm5654

My heads are on their way back to Quality Motorsports from WCCH with SS valves and bronze guides as well.

'06 Quicksilver Z06

Thanks for posting up.