Originally Posted by RedZ4me

Jimman, you're wrong about the your and you're.

Originally Posted by Vette @ 71

Old chinese proverb:

"Arguing with a contrarian only proves there are two"

Originally Posted by jimman

There is no proof either way, that's the point. Tell me your not an engineer.

Originally Posted by '06 Quicksilver Z06

The following are all possibilities, not just "bad juju":

[1] Bad surface finish on valve stems.
[2] Guide clearance can be out of spec when the LS7 leaves the factory
[3] Defective spring(s)
[4] Soft or abrasive guides.
[5] Heat

These along with "bad geometry" are outlined in the very first post of that thread. There may even be more. But the point is, "bad juju" is not the sole reason, and perhaps not even the primary reason why we are seeing guide wear.

Originally Posted by Michael_D

No sir, I have no first hand experience with BTR springs. I have had several phone conversations with Mr. Tooley when he was with Trick Flow, but that was years ago. He is a smart fella, smarter then me for sure. Based on the BTR price point with Ti retainers alone, I suspect they do not use Peterson wire.

Sometimes less is better. I had a 377 gen III sbc project that I fought with whilst on the dyno. It was built to spin 8500 rpm. I couldn’t get it to rev past 7900 without it falling on its face. I made a few phone calls and swapped out the springs to a different set with about 150# lower seat and 300# lower open pressure. First pull went straight to the rev limiter of 8500 – problem solved.

As you spend a lot of time on the track, I suspect your engine spends quite a bit of time at a particular rpm, right?? I’m guessing 5200 – 5600 rpm?? Well whatever it is, that needs to be communicated to the cam grinder to make sure the spring you run does not have inherent resonance at that particular rpm. As you intent to keep the OEM cam, I suggest you give PSI and PAC both a phone call and tell them what you intend to do. See what they have to say. There is no rule or law that says you can’t get several opinions…. I have had nothing but very straight forward, no nonsense, no BS conversations with these folks in the past. They know their business. They are not bashful or afraid to tell you that your idea is dumb or good.

With drag race engines the fixed resonance does not matter as much because the engine generally shoots through it. But with a road race set up where rpm is constant for longish periods of time, you really need to be a bit fussier with what you run. I would much rather run a beehive in a road race engine because they do not have a fixed resonance, if you can find one with the correct rate to work with the heavier valve.

Every time I see that quote from Crane earlier in the thread about how apposing spring pressure on the closing side of the lobe offsets the opening side I get a good laugh. They obviously forgot why lifters are called “followers”. The only time the spring forces equalize is when the starter is rolling the engine.

Here are two extremely informative quotes from Darin Morgan (no one in their right mind would say he is not an authority on heads and valve train dynamics). Don’t think that just because his reference is to race engines that the theory does not apply to this conversation.

Good luck…… mike

>>>>>>>>>>>>>>>>>>>>

Valve train design and tuning is a science all its own and has a little touch of mysticism as well. The Kinematic motion of a valve train is extremely complex. Simply stating that a spring needs "more" or "less" pressure is overly simplistic. It overlooks the finer tuning aspects of the system and especially the spring. The spring can encounter many different problems; float being just one of them. The spring can encounter Resonance, Coil surge, Float or simple Fatigue due to excessive heat or use. Float is the term most often used to describe the spring not controlling the valve train and in most cases people are correct in using this term because Float is the predominant valve train problem in most racing engines operating at moderately high engine speeds in the 7500 to 8000rpm range. This is due to either the builder not using the correct spring to control the valve train or the springs being used have fatigued with time and or heat. This is where the valves can bounces off the seat as much as .020 bleeding off the rising cylinder pressure back up the intake tract effectively shutting the engine off or keeping it from accelerating any further. Having two or three valve bounces of about .005 at the valve is a normal but albeit unhealthy occurrence in high rpm racing engines. We would like to have zero bounce, but that just doesn’t happen. Coil surge is a scenario that takes place when the spring is set up to far away from coil bind giving the middle coils room to bounce back and forth from top to bottom as the spring is closing. This usually takes place with a highly energized spring (fast ramp rate) at high engine speeds. Having a spring with not enough rate can exacerbate the problem and having a spring with both to little rate and not enough seat/nose pressure in conjunction with being set up to far from coil bind is down right deadly. I have seen springs turn blue, shatter and literally melt due to this scenario. This will cause valve bounce similar to floating the system and letting the valve hit the seat. Resonance is a killer but I find it a rare occurrence with the Super Series engines or other engines that operate at or below 7500rpm. In the big Block Chevy engine there are two distinct points within the rpm range that present a problem. 7600to 7800 and 9800-10000. 7600-7800 is usually just before the cam goes into loft (not float) and the 9800+ range is where the loft goes Bozo for a lack of a better term. The 7600-7800rpm point has been shown to excite certain types of springs that are considered to be "better" because of there increased rate and pressures. I put a set of PSI 048 style springs on a truck puller engine with the Raptor heads. I mistakenly thought that the “better " spring would lend some protection to the valve train because this guy revved the engine to 9600rpm+ and at time free revved the engine to 9500rpm+. Well he called me the after a week and said that he had broken six valve springs and the rest where Jell-O. They had lost 100lbs of seat pressure. I instantly knew to ask him one question. Do you hold the engine at or around 7600-7800rpm for any length of time? He reported that that is exactly where the engine dropped back down to when the sled came in. BINGO, resonance! I sent him A set of Comp 048 springs and told him to change them when they dropped below 285lbs. He has over 100runs on the engine and going strong. He replaces the valve springs about every 25 runs. This is the point I was trying to make. Just because a spring has more pressure or rate does not mean that it is a good match for the valve train system you are using them on. On a Drag racing engine that goes to 7600-8000 or 8500rpm on the shift, you won’t generally encounter this problem because the spring goes in and out of resonance so fast its of no consequence. If you just go to the point of resonance or just past it and back down through it, you’re generally ok. It’s when you “hang" there for any length of time that the damage becomes evident.
_________________
Darin Morgan
There is no pat answer for the proper procedure to set up valve springs. There are guide lines you should follow such as not taking the coils to bind and trying to set it up close to the manufactures recommendations. I always tell people that .050 away from coil bind is as tight as I would ever run a spring. I have never seen ( at least with the engines I have worked with) a spring that benefited from running it tighter than .050. Some springs like to be farther away from coil bind than others. On a Pro Stock engine they are about .120 away from coil bind. It depends on, the spring design, the camshafts lobe design, valve train weight and the amount of loft your are trying to control. The valve train weight and loft usually come into play with engine that operate at extreme engine speeds at or around 9000-10000rpm but Nextel Cup engines use these techniques as well.
To answer some of your questions, yes we do worry about both the open and closed pressures but the seat pressure much less than the open. In a perfect world the spring would have little pressure at close and about 1200 over the nose but this is not a perfect world so we have to set them up at about 425 on the seat to get that over the nose pressure and the proper rate to control the valve action. I wish I could get 200 on the seat and 1200 over the nose but they cant make a spring with that rate. An engine design is an exercise in compromise and that goes double for the valve train! The only way to learn what makes a particular engines valve train work is to get on a Spin Tron and the dyno and work it out over time. otherwise, you go off the camshaft and spring manufactures recommendations.

General rules of thumb,

(1) Don't get any closer than .050 to coil bind.
(2) As far as Seat pressure goes, A little too much will not hurt you but too little will DESTROY you!
(3) Follow the manufacture recommendations first before you venture out on your own. I say this because if you pick the wrong spring for a camshaft you will induce resonance into the valve train and hurt parts. Even if the spring has more pressure than what the manufacture wanted you to run! I cant count how many times people purchased some wiz bang HIGH pressure spring only to discover that its rate and coil design induced resonance some where in the power band and beat everything to death! Spring design still rates as a black art in my book.
_________________
Darin Morgan

Originally Posted by Mark200X

1. Quite possible.
2. Pretty much impossible since all or nearly all posted guide wear sheets show at least either the top or middle guide measurement to be within original spec (0.0026").
3. I don't understand what the wear mechanism would be.
4. Unlikely given the widespread use of what I assume is the same guide in many other LS engines, including the 6.
5. Possible if something else is also wrong.

Originally Posted by Random84

Interestingly, John_G's car (and others) with their bad geometry have gone 80,000+ miles....

Originally Posted by 50 4Ever

Maybe we can get this train wreck back on track...

Originally Posted by 50 4Ever

I will be getting SS exhaust valves, dual springs and brass guides. Work will be done by WCCH.

Originally Posted by '06 Quicksilver Z06

...



Good for you 50, I think you lost a motor awhile back too, didn't you.

I remember your name.

Anyway, I put you on the listing.

Good luck and all the best, you made a good move. Losing one motor is enough. More than enough.

Originally Posted by 50 4Ever

Never had an engine failure (yet) but I had an LS7 replaced under warranty on my last Z06 because oil was getting into the coolant.

Originally Posted by wolf8218

Sorry if this question is a bit low level for the discussion:

I read in the failure list thread that this problem can be identified from valve train clicking noises. Could some one please clarify what sort of sound level this is at? Every car I've ever driven has some sort of constant clicking noise when you open the hood and listen closely.

As a new owner, what days steps can you recommend (apart from John GS very informative thread).

Also any other preventative maintenance that I should look into?

I am of a medium tech level. (I can open up valve covers, replace accessory drives, etc)

Originally Posted by Dirty Howie

Thanks for the info !!

I will ask Richard if there are any other spring sets he would use with the stock cam. Specifically what he thinks of PSI and PAC. I may also call them.

Regardless, I am definitely going with SS valves.

So I'm just trying to get a feel of the equation in determining the spring. How much do the valve and cam profile affect it.


DH

Originally Posted by '06 Quicksilver Z06

Wolf, is the car in warranty?

If it is, and you are concerned about it, then I'd suggest taking it to a dealership and letting them take a listen to it.

Do you have plans of tracking the car or modding it?

If so, then you are going to want to pay close attention to these type threads which you apparently have already become familiar with, this one and the one by John.

The information in them, could well end up protecting you from a big repair bill, depending upon your planned use and warranty status.

Originally Posted by wolf8218

It's under GM warranty until February and VehicleOne exclusionary until Dec 2016.

I will not track it.

I'm on the "if it ain't broke don't fix it" boat, so I'd like to see if there's anything wrong before freaking out. If I miss anything, well, that's what the extended warranty is for. However I'd like to make sure I do everything I CAN do before the GM powertrain runs out, since it'll be smoother to do it that way.

Originally Posted by '06 Quicksilver Z06

Frankly, I wouldn't worry about any of this then wolf.

I would not even consider changing a thing, if you have an aftermarket warranty in play after the GM warranty runs out.

Because if you do, then it gives your aftermarket warranty company an out.

I do hope that you went about getting your Vehicle One warranty the right way, ie had the car inspected by a dealership or some other required facility, and that you have all of your prior receipts, and maintain your future receipts, for oil changes, indeed fluid changes of all types, and that you can demonstrate that these were done at the recommended intervals as per your owner's manual.

Because if you cannot do this, then it could affect your warranty coverage.

Furthermore, if you have any intentions of tracking the car, or if you are tracking it, then I would not put that information on this forum, in print, and especially not in the form of video, as there have actually been people "busted" right in here, after popping a motor, and it later being discovered that the car had been tracked. And of course being denied warranty coverage.

Good luck, wolf.

Originally Posted by wolf8218

I fixed that post, you should fix my quote for spelling errors.

As far as the inspection, yes, I had them follow the checklist provided by Dennis Fichtner, and I paid Munday Chevy 149$ for the used car inspection.

Would they deny the claim even if work was done by that same accredited GM dealership?

Originally Posted by Michael_D

Hi again –

I am sure that Richard would not steer you towards a spring, or any service/product that would not be fit for purpose. I do not think any of the reputable head suppliers would do that actually. In this day and age, it’s a pretty dumb move to try and sell junk because that will eventually hit the forums and kill their reputation.

But having said that….there’s always a ‘but’.

These folks are selling a product. The bulk of their sales are to “enthusiasts” who are constantly trying to save a buck. I know, I’ve heard it time and time again. The first thing out of their mouth is “How much do you charge for ……?” “How much does that cost?”

So keeping this in mind, they have to be competitive with their prices if they want to stay in business. One way to do this is to buy bulk to get a better jobber price from the vendor. So with regards to springs, they will find a few different spring sets that cover a wide range of applications. So what you get from the head supplier will more than likely work just fine, but there quite possibly is a better spring for your particular application that they do not have on hand – but could get for you if asked. The 377 example I used earlier is one that I learned from. I told the supplier exactly what the engine was, operating rpm, and all the components being used. I was assured that the springs that came with these heads would work just fine. Well they didn't. After that experience, I made it a point to consult the cam grinder first, then the spring supplier, then whoever happened to be working the heads (if I was not personally doing the work).

One way to give the head supplier an “out”, is to ask them what they would do if this was their engine, their car, and cost was not the primary consideration. I have found that when doing this, the tone of the conversation changes somewhat. The supplier then no longer feels pressure to make a sale that is based primarily on price, and that you are more concerned with getting the best product. They will generally give a few options, ranging from overkill to ‘good enough’.

Valve weight has a significant impact, as well as cam profile, rocker mass / stiffness / ratio, valve train rigidity, spring mass, retainer weight, push rod rigidity....the list goes on and on. It is an overly complex subject that gives me a headache. Cam grinders (the ones who actually grind the cams) have already done most of the testing with multiple scenarios with different lobe families. Comp pioneered that tech (spin rigs) a couple decades ago. But they obviously can not test every single variable.