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Valve stem seals crushed, LS7. More spring?

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Re: Valve stem seals crushed, LS7. More spring?

Postby JonSimpson » Tue Jan 10, 2017 11:51 pm

Whoever sold you the valve springs you were using should be shot. There is no way I would use that spring with the kind of valvetrain mass you are dealing with, not even on something at stable as a HUC lobe. Not that it matters as you are going with another package now. Just my $0.02, carry on.
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Re: Valve stem seals crushed, LS7. More spring?

Postby mdrew » Wed Jan 11, 2017 9:18 am

airflowdevelop wrote:Mdrew I don't think that Texas Speed has all the answers. Along with that nothing against Geoff but I would prefer that you spoke to Kip Fabre @ CM if you can. If you want access to a spintron I might know a guy. On another note that RWTECH guy might just be spot on. Not that he or I know anything about LS motors.


I did.... Were you aware that CamMotion is grinding EPS camshafts?
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Re: Valve stem seals crushed, LS7. More spring?

Postby mdrew » Wed Jan 11, 2017 9:23 am

JonSimpson wrote:Whoever sold you the valve springs you were using should be shot. There is no way I would use that spring with the kind of valvetrain mass you are dealing with, not even on something at stable as a HUC lobe. Not that it matters as you are going with another package now. Just my $0.02, carry on.


To be fair, I'm the one who screwed up. The springs were originally spec'ed for OEM rockers, OEM valves - and this camshaft. I, under my own conscience and completely sober, decided to go with the roller tipped rocker. I did not consider seat load, and thought that surely - 470 pounds open load was enough. I'm the only dumbass to blame for this.

I decided to move to a roller rocker - after the OEM rockers obliterated the (newly installed) valve guides (valve guide liners to be more accurate) in less than 5K miles use. So bad, many were out of range of my bore scope, and I'm just lucky I didn't break a few valves off...... The same OEM rockers that soooooooooooo many LS motor pro's told me were good for + .750" lift. So while the OEM rockers might just be the best thing since sliced bread, and wonderfully light and good for many revs, they are NOT good for high lift and I don't give a rat's ass what anyone says to the contrary, or what lift they were "designed" for.
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Re: Valve stem seals crushed, LS7. More spring?

Postby Kevin Johnson » Wed Jan 11, 2017 9:58 am

mdrew wrote:...
I decided to move to a roller rocker - after the OEM rockers obliterated the (newly installed) valve guides (valve guide liners to be more accurate) in less than 5K miles use. So bad, many were out of range of my bore scope, and I'm just lucky I didn't break a few valves off...... The same OEM rockers that soooooooooooo many LS motor pro's told me were good for + .750" lift. So while the OEM rockers might just be the best thing since sliced bread, and wonderfully light and good for many revs, they are NOT good for high lift and I don't give a rat's ass what anyone says to the contrary, or what lift they were "designed" for.


mdrew previously wrote:I ran this same set up with OEM rockers, and the lighter OEM SI valves the second time I rebuilt the engine and heads. No damaged seals. The only change was the Crower rockers and heavier Ferrea exh valves.


It is good that you gave us this additional information because it presents an entirely different picture of the previous build.
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Re: Valve stem seals crushed, LS7. More spring?

Postby mdrew » Wed Jan 11, 2017 12:30 pm

I have been trying to be discreet, and not get into too many details that would lead this discussion in a direction filled with conflict, emotions, and stupidity. And, I am not the type to throw anyone under a buss.
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Re: Valve stem seals crushed, LS7. More spring?

Postby Kevin Johnson » Wed Jan 11, 2017 12:51 pm

mdrew wrote:I have been trying to be discreet, and not get into too many details that would lead this discussion in a direction filled with conflict, emotions, and stupidity. And, I am not the type to throw anyone under a buss.


What type of valve guides did you use on the latest build and did you notice any unusual wear?
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Re: Valve stem seals crushed, LS7. More spring?

Postby mdrew » Wed Jan 11, 2017 1:22 pm

Kevin Johnson wrote:
What type of valve guides did you use on the latest build and did you notice any unusual wear?


The last head R&R, I had the head builder fit his proprietary PM guides, which were basically HD truck guides with internal oil groves. The seat side (bottom) of the guides did show wear, but nothing unusual or unexpected. The intakes had more wear than the exh, but seat runout was more than I like to see on the intakes, so I was expecting to see it. If I would not have lost an entire season of driving the car, I would not have installed the heads. The shop was informed of my runout readings at the time and offered to rework the heads. They are going back to him for rework now.
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Re: Valve stem seals crushed, LS7. More spring?

Postby RW TECH » Wed Jan 11, 2017 9:38 pm

mdrew wrote:
JonSimpson wrote:Whoever sold you the valve springs you were using should be shot. There is no way I would use that spring with the kind of valvetrain mass you are dealing with, not even on something at stable as a HUC lobe. Not that it matters as you are going with another package now. Just my $0.02, carry on.


To be fair, I'm the one who screwed up. The springs were originally spec'ed for OEM rockers, OEM valves - and this camshaft. I, under my own conscience and completely sober, decided to go with the roller tipped rocker. I did not consider seat load, and thought that surely - 470 pounds open load was enough. I'm the only dumbass to blame for this.

I decided to move to a roller rocker - after the OEM rockers obliterated the (newly installed) valve guides (valve guide liners to be more accurate) in less than 5K miles use. So bad, many were out of range of my bore scope, and I'm just lucky I didn't break a few valves off...... The same OEM rockers that soooooooooooo many LS motor pro's told me were good for + .750" lift. So while the OEM rockers might just be the best thing since sliced bread, and wonderfully light and good for many revs, they are NOT good for high lift and I don't give a rat's ass what anyone says to the contrary, or what lift they were "designed" for.


If the LS motor pros told you the stock rockers are designed to function well with .750" lift, they are not actually LS motor pros. As far as giving a rat's ass that's up to you but what I'm stating is an absolute, measurable fact. Nothing emotional about it and I am not guessing my way through any of this.

Not saying I think the stock LS7 guide is "great" but your problems are far beyond what would normally happen with an LS7 guide if the lift was kept at or below the rocker's designed maximum lift and if the valvetrain was in good control.

Otherwise the off-road trucks could never have raced 2,000 - up miles on their combinations with engine speeds well above 7,000 RPM. Same with the COPO's that run above 8,000 RPM.

I'm glad you're taking the approach you're on now & I'm sure it'll make you happy.
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Re: Valve stem seals crushed, LS7. More spring?

Postby mdrew » Thu Jan 12, 2017 9:20 am

RW TECH wrote:
mdrew wrote:
JonSimpson wrote:Whoever sold you the valve springs you were using should be shot. There is no way I would use that spring with the kind of valvetrain mass you are dealing with, not even on something at stable as a HUC lobe. Not that it matters as you are going with another package now. Just my $0.02, carry on.


To be fair, I'm the one who screwed up. The springs were originally spec'ed for OEM rockers, OEM valves - and this camshaft. I, under my own conscience and completely sober, decided to go with the roller tipped rocker. I did not consider seat load, and thought that surely - 470 pounds open load was enough. I'm the only dumbass to blame for this.

I decided to move to a roller rocker - after the OEM rockers obliterated the (newly installed) valve guides (valve guide liners to be more accurate) in less than 5K miles use. So bad, many were out of range of my bore scope, and I'm just lucky I didn't break a few valves off...... The same OEM rockers that soooooooooooo many LS motor pro's told me were good for + .750" lift. So while the OEM rockers might just be the best thing since sliced bread, and wonderfully light and good for many revs, they are NOT good for high lift and I don't give a rat's ass what anyone says to the contrary, or what lift they were "designed" for.


If the LS motor pros told you the stock rockers are designed to function well with .750" lift, they are not actually LS motor pros. As far as giving a rat's ass that's up to you but what I'm stating is an absolute, measurable fact. Nothing emotional about it and I am not guessing my way through any of this.

Not saying I think the stock LS7 guide is "great" but your problems are far beyond what would normally happen with an LS7 guide if the lift was kept at or below the rocker's designed maximum lift and if the valvetrain was in good control.

Otherwise the off-road trucks could never have raced 2,000 - up miles on their combinations with engine speeds well above 7,000 RPM. Same with the COPO's that run above 8,000 RPM.

I'm glad you're taking the approach you're on now & I'm sure it'll make you happy.


My original post, and this entire thread was to verify my initial thoughts that the valve train was not happy and beat the crap out of valve seals. Had nothing to do with valve guide wear......I intentionally tried to avoid that hot mess of a topic.

I posted my personal observations about lift and the OE rockers, and what my measurements came up with --- as a response to an inquiry about how I ended up with the roller tipped rockers. You then countered that with what lift the OE rockers were designed to support, which was more than what my measurements indicate. I'm sticking with what I measured, and not what they were designed for. Which, coincidentally, is pretty close to the lift that truck engine of yours and the COPO has with the GM stage 3 cam.......right? Knowing what I know today, and if I were starting from scratch, I would not mess with ANY roller tipped rocker on this engine for street duty, and I'd keep lift under .630".

Just take a look at what Lingenfelter has doing, and still is doing with their LS7 engine packages. Lifts in the .700" range, and they are very adamant that the OEM rockers be used. The Comp LSK lobe origins is LPE... That's just one example. No less than two professional engine builders, and at least one cylinder head professionals on this board told me these rockers were good for lfts over .750". That was about three years ago, so maybe they've changed their opinion since then? LS / Vette shops all over the country are selling engine packages and they have lifts over .650", some over .700"....They all advocate stock rocker use. And most, by a long shot, get rid of the OE exh valve and run a solid stemmed valve. None of these shops spin test their packages either (with the exception of Katech). Tony Mamo is selling his new cylinder heads (his CNC porting on Trick Flow castings), and they come with hollow stemmed stainless intake valve, and solid stemmed exh valves. He's also selling these heads with his variant of YT roller tipped rockers. No spin testing of any sort - I know because I asked and he said he doesn't need to. He "engineered" his system.

I'm not making this crap up. It's all easily verified.
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Re: Valve stem seals crushed, LS7. More spring?

Postby CGT » Thu Jan 12, 2017 10:30 am

mdrew wrote:No spin testing of any sort - I know because I asked and he said he doesn't need to. He "engineered" his system.

There seems to be alot of "engineered" stuff in this industry, and heaven forbid you question the "experts"
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Re: Valve stem seals crushed, LS7. More spring?

Postby Warp Speed » Thu Jan 12, 2017 12:49 pm

The lift limit is brought on by the body length of the rocker, and it's ability to give an acceptable tip sweep for the desired valve lift. A short rocker body length offer a very stiff design, while maintaining a low weight, and also keeping material costs down. This comes at the price of being lift limited.
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Re: Valve stem seals crushed, LS7. More spring?

Postby RW TECH » Thu Jan 12, 2017 9:05 pm

mdrew wrote:
My original post, and this entire thread was to verify my initial thoughts that the valve train was not happy and beat the crap out of valve seals. Had nothing to do with valve guide wear......I intentionally tried to avoid that hot mess of a topic.

I posted my personal observations about lift and the OE rockers, and what my measurements came up with --- as a response to an inquiry about how I ended up with the roller tipped rockers. You then countered that with what lift the OE rockers were designed to support, which was more than what my measurements indicate. I'm sticking with what I measured, and not what they were designed for. Which, coincidentally, is pretty close to the lift that truck engine of yours and the COPO has with the GM stage 3 cam.......right? Knowing what I know today, and if I were starting from scratch, I would not mess with ANY roller tipped rocker on this engine for street duty, and I'd keep lift under .630".

Just take a look at what Lingenfelter has doing, and still is doing with their LS7 engine packages. Lifts in the .700" range, and they are very adamant that the OEM rockers be used. The Comp LSK lobe origins is LPE... That's just one example. No less than two professional engine builders, and at least one cylinder head professionals on this board told me these rockers were good for lfts over .750". That was about three years ago, so maybe they've changed their opinion since then? LS / Vette shops all over the country are selling engine packages and they have lifts over .650", some over .700"....They all advocate stock rocker use. And most, by a long shot, get rid of the OE exh valve and run a solid stemmed valve. None of these shops spin test their packages either (with the exception of Katech). Tony Mamo is selling his new cylinder heads (his CNC porting on Trick Flow castings), and they come with hollow stemmed stainless intake valve, and solid stemmed exh valves. He's also selling these heads with his variant of YT roller tipped rockers. No spin testing of any sort - I know because I asked and he said he doesn't need to. He "engineered" his system.

I'm not making this crap up. It's all easily verified.


I'm not really interested in what this guy or that guy does. Noticed that I kept things nice by not directly saying "Your blah-blah-blah brand this or that is wrong"? I did drop a hard hint about a component & glad to see movement there.

Instead of pitching my favorite brand of whatever I have for sale or whatever my pet theory is this week or whatever my favorite hot rod guy said on the internet yesterday, I tried to steer you down a path where you'd know for sure what you have is truly going to work and live. You would also know what to look for next time & get even more out of it because you know the physical limits with data to prove it.

The off-road example is a system that has been proven to be reliable in one of the most severe applications on wheels. If I caused offense by showing that to you please be assured I will have no problem in signing off with you. I gave you that example because I know for sure what it is actually capable of.

Think what you want, my wasting time typing in this thread & steering you towards certainty with real information about real things that were really measured & really proven to work was not done to hurt your feelings or pick on your car.
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Re: Valve stem seals crushed, LS7. More spring?

Postby RW TECH » Thu Jan 12, 2017 9:06 pm

Warp Speed wrote:The lift limit is brought on by the body length of the rocker, and it's ability to give an acceptable tip sweep for the desired valve lift. A short rocker body length offer a very stiff design, while maintaining a low weight, and also keeping material costs down. This comes at the price of being lift limited.


I don't believe you. LOL!!!! J/K. :D
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Re: Valve stem seals crushed, LS7. More spring?

Postby mdrew » Thu Jan 12, 2017 10:17 pm

RW TECH wrote:
I'm not really interested in what this guy or that guy does. Noticed that I kept things nice by not directly saying "Your blah-blah-blah brand this or that is wrong"? I did drop a hard hint about a component & glad to see movement there.

Instead of pitching my favorite brand of whatever I have for sale or whatever my pet theory is this week or whatever my favorite hot rod guy said on the internet yesterday, I tried to steer you down a path where you'd know for sure what you have is truly going to work and live. You would also know what to look for next time & get even more out of it because you know the physical limits with data to prove it.

The off-road example is a system that has been proven to be reliable in one of the most severe applications on wheels. If I caused offense by showing that to you please be assured I will have no problem in signing off with you. I gave you that example because I know for sure what it is actually capable of.

Think what you want, my wasting time typing in this thread & steering you towards certainty with real information about real things that were really measured & really proven to work was not done to hurt your feelings or pick on your car.


You totally misread the tone of my post. I was AGREEING with your assertations regarding this engine and valve train dynamics. No where have you written anything that I took offense to. If anything, I'm pissed off at the aforementioned "professionals" steering folks in the wrong direction, which they are constantly doing to sell their stuff.

Like I said, I really do wish I had the time, means, and money to haul my crap to a facility with a spin rig and run a couple dozen iterations. I do not, and neither do 95% of the rest of guys working paycheck to paycheck do. The horse has left the barn, and I'm just trying to ride it.

And for what it's worth, I have been communicating with someone who does have a lot of experience with LS engines running the same rocker system (and others), with cams that have lobes much more aggressive than the one I am using. He told me I need a lot more seat pressure. He's suggesting 170# on the seat, and 475# open. I'm surfing the PAC rate sheet now.....
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Re: Valve stem seals crushed, LS7. More spring?

Postby Phipp85 » Wed Feb 08, 2017 11:58 pm

Any further progress on this?
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