[Z06] Have any "fixed heads" failed ?
08-28-2015, 09:51 AM
#101
08-30-2015, 03:51 PM
#102
Melting Slicks
08-30-2015, 08:44 PM
#103
So is there a solution to bullet proof ls7 - last guy told me basically I need to check my guides and stuff every 10k miles despite having wcch stage 2 heads. (Bronze guides, solid stainless intakes - tumbled titanium exhausts) stock 70cc chambers have no idea what springs where used as vengeance racing is stupid and keeps records by first and last name so can't tell me **** about what the previous did - I only know from what he could remeber and what wcch could tell me from the serial number :/
08-31-2015, 09:02 AM
#104
Instructor
So is there a solution to bullet proof ls7 - last guy told me basically I need to check my guides and stuff every 10k miles despite having wcch stage 2 heads. (Bronze guides, solid stainless intakes - tumbled titanium exhausts) stock 70cc chambers have no idea what springs where used as vengeance racing is stupid and keeps records by first and last name so can't tell me **** about what the previous did - I only know from what he could remeber and what wcch could tell me from the serial number :/
08-31-2015, 09:24 AM
#105
Melting Slicks
Hmm Ok .. strange Paul, since I was reading threads from back this spring about final R&D from TEA/TFS on the LS7 TFS 260's and that they would be on sale sometime this summer, I mean Summit Racing own TEA TFS and those heads are a NEW item in their latest Summit mag.... I dunno.. lol.. congrats on the TFS!
A year earlier I got a pair of TFS255s for my CTS-V, those heads (and the guys at TFS, particularly the guy doing their dyno/durability testing) impressed me enough to ensure I got a pair of the 260s for my Z.
Cheers, Paul.
08-31-2015, 09:35 AM
#106
Le Mans Master
So is there a solution to bullet proof ls7 - last guy told me basically I need to check my guides and stuff every 10k miles despite having wcch stage 2 heads. (Bronze guides, solid stainless intakes - tumbled titanium exhausts) stock 70cc chambers have no idea what springs where used as vengeance racing is stupid and keeps records by first and last name so can't tell me **** about what the previous did - I only know from what he could remeber and what wcch could tell me from the serial number :/
But to your concerns, IMO (I have to say that, and will still get blasted by some) if you are running the stock rockers, you aren't completely out of the woods to have the guides go out of spec again.
..and even with my "bullet-proof" solution, I will still check the guides approximately every 10K (external "wiggle test" by hand, the "go / no-go" version).
Last edited by Dan_the_C5_Man; 08-31-2015 at 10:03 AM.
08-31-2015, 10:07 AM
#107
You have it reversed, the intakes are Ti, exhausts are stainless..
But to your concerns, IMO (I have to say that, and will still get blasted by some) if you are running the stock rockers, you aren't completely out of the woods to have the guides go out of spec again.
But to your concerns, IMO (I have to say that, and will still get blasted by some) if you are running the stock rockers, you aren't completely out of the woods to have the guides go out of spec again.
My own car (I posted guide measurements years ago) had 17k on original heads with a 110 torquer cam all that time and my guides were perfectly fine and in spec. Many would argue that if the rockers were a contributing factor to the issue, a cam will exacerbate the issue. If true, how could the data show what it does for my example and numerous others? Also, if the rockers contribute greatly to the cause, why would some have excessive wear on the intake guides, some have excessive wear on the exhaust guides, some have excessive wear on both sides, and some have no excessive wear at all? The data just doesn't support this at all.
I can't say whether or not my WCCH heads with bronze guides and OEM valves are in or out of spec at 15,000 miles. However, knowing my first set of heads remained in spec with these rockers, I wouldn't say they were the cause if my rebuilt heads indicate excessive wear upon a tear down.
08-31-2015, 11:31 AM
#108
Team Owner
The rocker theory, just like the heat theory, has not been supported by data in any way thus far in these discussions.
My own car (I posted guide measurements years ago) had 17k on original heads with a 110 torquer cam all that time and my guides were perfectly fine and in spec. Many would argue that if the rockers were a contributing factor to the issue, a cam will exacerbate the issue. If true, how could the data show what it does for my example and numerous others? Also, if the rockers contribute greatly to the cause, why would some have excessive wear on the intake guides, some have excessive wear on the exhaust guides, some have excessive wear on both sides, and some have no excessive wear at all? The data just doesn't support this at all.
I can't say whether or not my WCCH heads with bronze guides and OEM valves are in or out of spec at 15,000 miles. However, knowing my first set of heads remained in spec with these rockers, I wouldn't say they were the cause if my rebuilt heads indicate excessive wear upon a tear down.
My own car (I posted guide measurements years ago) had 17k on original heads with a 110 torquer cam all that time and my guides were perfectly fine and in spec. Many would argue that if the rockers were a contributing factor to the issue, a cam will exacerbate the issue. If true, how could the data show what it does for my example and numerous others? Also, if the rockers contribute greatly to the cause, why would some have excessive wear on the intake guides, some have excessive wear on the exhaust guides, some have excessive wear on both sides, and some have no excessive wear at all? The data just doesn't support this at all.
I can't say whether or not my WCCH heads with bronze guides and OEM valves are in or out of spec at 15,000 miles. However, knowing my first set of heads remained in spec with these rockers, I wouldn't say they were the cause if my rebuilt heads indicate excessive wear upon a tear down.
"Sam Winegarden: Executive Director of Engine Engineering, GM Powertrain
Throughout his long career with General Motors, Sam Winegarden has had a need for speed.
As GM Powertrain’s executive director of engine engineering, Winegarden is the company’s top engine executive, overseeing the development and production of engines for the company’s entire portfolio.
Winegarden was appointed to his current post in 2004. In March 2011, he also assumed co-leadership with Jim Lanzon of Powertrain Engineering.
Winegarden began his career with General Motors in 1969 as an engineering co-op student with Buick Motor Division in Flint, Mich., while attending General Motors Institute.
He worked for Buick for several years, primarily working with the 3800 (3.8L V-6) engine.
He held several engineering positions of increasing responsibility with Buick and the former Buick-Olds-Cadillac (BOC) Group. In 1986 he joined BOC-Flint Powertrain as Director of Validation. In 1989 he was appointed chief engineer of BOC-Detroit Powertrain.
In this capacity he was responsible for the 4.9L V-8, Northstar V-8 and premium V-6 engines. In 1998 he became chief engineer and program manager for the small-block product team.
He earned a bachelor’s degree in mechanical engineering from General Motors Institute in 1974 and an MBA from the University of Michigan in 1986."
But, he's not going to say anything about the problem to us, so It's up to us layman to muddle our way through the different "theory's" and hope we make the correct decision(do nothing, rebuild factory heads, install aftermarket heads, etc) that will give us a solution that will last for 100,000 trouble free miles.
It's truly a shame that GM has decided to shaft the consumers that decided to spend from $65,000 to over a $100,000, for the "top dog" in GM's lineup starting in 2005(calendar year for 2006 MY).
It's a fairly expensive procedure to properly measure the valve guide clearances to see if they are out of GM's field service spec, as that requires removal of the heads, disassembling them and measuring each guide and then installing new head gaskets and head bolts for the re-assembly. I doubt if any reputable shop that knows the LS7 inside and out, will do that for under $800 to $1,000. Not everybody lives next door to those reputable shops. The closest to me is LG Motorsports which is 409 miles away(and that costs additional money to take the car to them and then come back later to pick it up).
If you are going to spend that money to check your heads, you might as well either rebuild your heads or replace them with aftermarket heads for another couple of thousand.
It would be nice if GM would tell us just what needs to be done, after the inspection, to "fix" the heads so they don't have to be re-inspected 5,000-10,000 miles down the road, as some have suggested. But GM won't do us that courtesy.
Spending thousands of dollars to "fix" the problem and then not having any confidence that they are really 'fixed" is asinine.
My daily driver will need replacing in the near future, but it won't be a GM product. I'm not going through this crap again(I did it the first time with a new 1970(or 1971) Vega that was trash at 30,000 miles because of a poor design decision by GM that caused my car to burn a quart of oil every 200 miles, and they would only "fix" the problem while it was in their short warranty period. And now I'm doing it with my Z06.
I guess I'm lucky that I didn't buy an early 80's Olds or Caddy with the 350 diesel engine or the Caddy with the 4-6-8 engine. Most of those that did got burned by GM also. An early 80's Olds with the diesel had absolutely no resale valve and many owners had to replace the failed diesel with a gas engine to keep the car on the road, early in a normal life cycle for a car.
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SSMOKE (07-02-2016)
08-31-2015, 12:10 PM
#109
Le Mans Master
That said, there are a few key points that are not debateable;
1. A roller-tipped rocker has a significantly smaller sweep across the face of a valve tip as compared to the stock GM LSx design.
2. A roller-tipped rocker presents significantly less side-loading to the face of the valve tip as compared to the stock GM LSx design.
3. All of the excessive valve guide clearance issues we've seen reveal a predictable pattern - North / South is excessively worn, East / West is not. This pattern of wear is consistent with valve tip loading.
4. I clearly witnessed wear patterns on the stock rockers that were all over the place - a few looked fine, most had a pattern of wear that indicated geometry issues, and it is unclear if those issues were caused by the excessive slop in the stock trunion bearings or due to the beginnings of VG wear, or both. The bottom line is, I did not like what I saw.
If your configuration allows it (target mechanical RPM limit, cam lift and lobe profile, spring pressure, total MOI of the assembly), and cost is not a prohibitive factor, why wouldn't you run a roller-tipped rocker, as additional insurance against guide wear? I don't see a down-side (keep in mind, I've already accounted for the valve train dynamics referenced above).
I don't think you'll disagree with the above - I think you disagree to what level the stock rocker plays within our guide wear issues (in your argument, apparently zero).
I don't see a lot of value in blindly defending GM's engineering expertise in this particular case (not that you were doing so, but in general); after all, if the design and execution was perfect, we wouldn't have these discussions in the first place..
Last edited by Dan_the_C5_Man; 08-31-2015 at 01:39 PM.
08-31-2015, 12:20 PM
#110
Melting Slicks
The guy that has all the answers to what is contributing to the LS7 failures, either from initial bad machining of the guides or bad machining in of the rocker pedestals, or bad finishes on the valve stems, or a design problem not allowing for proper cooling of the exhaust valve, etc or a combination of them, is...
"Sam Winegarden: Executive Director of Engine Engineering, GM Powertrain
Throughout his long career with General Motors, Sam Winegarden has had a need for speed.
As GM Powertrain’s executive director of engine engineering, Winegarden is the company’s top engine executive, overseeing the development and production of engines for the company’s entire portfolio.
Winegarden was appointed to his current post in 2004. In March 2011, he also assumed co-leadership with Jim Lanzon of Powertrain Engineering.
Winegarden began his career with General Motors in 1969 as an engineering co-op student with Buick Motor Division in Flint, Mich., while attending General Motors Institute.
He worked for Buick for several years, primarily working with the 3800 (3.8L V-6) engine.
He held several engineering positions of increasing responsibility with Buick and the former Buick-Olds-Cadillac (BOC) Group. In 1986 he joined BOC-Flint Powertrain as Director of Validation. In 1989 he was appointed chief engineer of BOC-Detroit Powertrain.
In this capacity he was responsible for the 4.9L V-8, Northstar V-8 and premium V-6 engines. In 1998 he became chief engineer and program manager for the small-block product team.
He earned a bachelor’s degree in mechanical engineering from General Motors Institute in 1974 and an MBA from the University of Michigan in 1986."
But, he's not going to say anything about the problem to us, so It's up to us layman to muddle our way through the different "theory's" and hope we make the correct decision(do nothing, rebuild factory heads, install aftermarket heads, etc) that will give us a solution that will last for 100,000 trouble free miles.
It's truly a shame that GM has decided to shaft the consumers that decided to spend from $65,000 to over a $100,000, for the "top dog" in GM's lineup starting in 2005(calendar year for 2006 MY).
It's a fairly expensive procedure to properly measure the valve guide clearances to see if they are out of GM's field service spec, as that requires removal of the heads, disassembling them and measuring each guide and then installing new head gaskets and head bolts for the re-assembly. I doubt if any reputable shop that knows the LS7 inside and out, will do that for under $800 to $1,000. Not everybody lives next door to those reputable shops. The closest to me is LG Motorsports which is 409 miles away(and that costs additional money to take the car to them and then come back later to pick it up).
If you are going to spend that money to check your heads, you might as well either rebuild your heads or replace them with aftermarket heads for another couple of thousand.
It would be nice if GM would tell us just what needs to be done, after the inspection, to "fix" the heads so they don't have to be re-inspected 5,000-10,000 miles down the road, as some have suggested. But GM won't do us that courtesy.
Spending thousands of dollars to "fix" the problem and then not having any confidence that they are really 'fixed" is asinine.
My daily driver will need replacing in the near future, but it won't be a GM product. I'm not going through this crap again(I did it the first time with a new 1970(or 1971) Vega that was trash at 30,000 miles because of a poor design decision by GM that caused my car to burn a quart of oil every 200 miles, and they would only "fix" the problem while it was in their short warranty period. And now I'm doing it with my Z06.
I guess I'm lucky that I didn't buy an early 80's Olds or Caddy with the 350 diesel engine or the Caddy with the 4-6-8 engine. Most of those that did got burned by GM also. An early 80's Olds with the diesel had absolutely no resale valve and many owners had to replace the failed diesel with a gas engine to keep the car on the road, early in a normal life cycle for a car.
"Sam Winegarden: Executive Director of Engine Engineering, GM Powertrain
Throughout his long career with General Motors, Sam Winegarden has had a need for speed.
As GM Powertrain’s executive director of engine engineering, Winegarden is the company’s top engine executive, overseeing the development and production of engines for the company’s entire portfolio.
Winegarden was appointed to his current post in 2004. In March 2011, he also assumed co-leadership with Jim Lanzon of Powertrain Engineering.
Winegarden began his career with General Motors in 1969 as an engineering co-op student with Buick Motor Division in Flint, Mich., while attending General Motors Institute.
He worked for Buick for several years, primarily working with the 3800 (3.8L V-6) engine.
He held several engineering positions of increasing responsibility with Buick and the former Buick-Olds-Cadillac (BOC) Group. In 1986 he joined BOC-Flint Powertrain as Director of Validation. In 1989 he was appointed chief engineer of BOC-Detroit Powertrain.
In this capacity he was responsible for the 4.9L V-8, Northstar V-8 and premium V-6 engines. In 1998 he became chief engineer and program manager for the small-block product team.
He earned a bachelor’s degree in mechanical engineering from General Motors Institute in 1974 and an MBA from the University of Michigan in 1986."
But, he's not going to say anything about the problem to us, so It's up to us layman to muddle our way through the different "theory's" and hope we make the correct decision(do nothing, rebuild factory heads, install aftermarket heads, etc) that will give us a solution that will last for 100,000 trouble free miles.
It's truly a shame that GM has decided to shaft the consumers that decided to spend from $65,000 to over a $100,000, for the "top dog" in GM's lineup starting in 2005(calendar year for 2006 MY).
It's a fairly expensive procedure to properly measure the valve guide clearances to see if they are out of GM's field service spec, as that requires removal of the heads, disassembling them and measuring each guide and then installing new head gaskets and head bolts for the re-assembly. I doubt if any reputable shop that knows the LS7 inside and out, will do that for under $800 to $1,000. Not everybody lives next door to those reputable shops. The closest to me is LG Motorsports which is 409 miles away(and that costs additional money to take the car to them and then come back later to pick it up).
If you are going to spend that money to check your heads, you might as well either rebuild your heads or replace them with aftermarket heads for another couple of thousand.
It would be nice if GM would tell us just what needs to be done, after the inspection, to "fix" the heads so they don't have to be re-inspected 5,000-10,000 miles down the road, as some have suggested. But GM won't do us that courtesy.
Spending thousands of dollars to "fix" the problem and then not having any confidence that they are really 'fixed" is asinine.
My daily driver will need replacing in the near future, but it won't be a GM product. I'm not going through this crap again(I did it the first time with a new 1970(or 1971) Vega that was trash at 30,000 miles because of a poor design decision by GM that caused my car to burn a quart of oil every 200 miles, and they would only "fix" the problem while it was in their short warranty period. And now I'm doing it with my Z06.
I guess I'm lucky that I didn't buy an early 80's Olds or Caddy with the 350 diesel engine or the Caddy with the 4-6-8 engine. Most of those that did got burned by GM also. An early 80's Olds with the diesel had absolutely no resale valve and many owners had to replace the failed diesel with a gas engine to keep the car on the road, early in a normal life cycle for a car.
08-31-2015, 12:44 PM
#111
Team Owner
I plan to keep mine, so I'm working on scheduling some time to get it fixed at AHP...under my GMPP warranty no less. If you feel its in your best interest to sell, then sell it...I understand. Many others have done the same. I may have even felt similarly if I didn't at least have a GMPP to fall back on to cover a good portion of the repairs, and luckily I don't need to utilize OE parts for those repairs. In the end, just do what you feel is best for you, and who cares what anyone else thinks or says.
08-31-2015, 01:04 PM
#112
Team Owner
Meh...some people flame, some people could care less. Ultimately its your car, your decision. Some are of the mindset that its no big deal, others just view it as the C6Z is nothing more than a car...a car that GM dropped the ball on.
I plan to keep mine, so I'm working on scheduling some time to get it fixed at AHP...under my GMPP warranty no less. If you feel its in your best interest to sell, then sell it...I understand. Many others have done the same. I may have even felt similarly if I didn't at least have a GMPP to fall back on to cover a good portion of the repairs, and luckily I don't need to utilize OE parts for those repairs. In the end, just do what you feel is best for you, and who cares what anyone else thinks or says.
I plan to keep mine, so I'm working on scheduling some time to get it fixed at AHP...under my GMPP warranty no less. If you feel its in your best interest to sell, then sell it...I understand. Many others have done the same. I may have even felt similarly if I didn't at least have a GMPP to fall back on to cover a good portion of the repairs, and luckily I don't need to utilize OE parts for those repairs. In the end, just do what you feel is best for you, and who cares what anyone else thinks or says.
You paid for the GMPP warranty and I paid for directly my PRC265 heads to "hopefully" fix GM's mistake. Are you certain your new heads are truly "fixed" and will give you no more valve problems in the future?
Since I've already done the "fix" LOL, I'm planning on keeping my Z06 and will just "hope" for the best outcome.
If not, I'll be out some real $$$$ for a new engine in the future. I really shouldn't even have to think about that happening, if GM would tell us what truly is a "fix" for the valve problem.
GM says the valve problem is only a problem for cars built during a short time period and they corrected the problem and started inspecting 100%, but that seems to less than truthful, as many have reported valve problems in Z06's built outside of GM's window of "bad machining".
08-31-2015, 01:45 PM
#113
Team Owner
Yes, I will be when they are done. Are you?
08-31-2015, 02:15 PM
#115
Team Owner
Never said that...that's something you came up with. But based on what my GMPP cost me (~$900), I'll be way ahead of most with the repair expense. At least that money I spent on the GMPP will go towards something useful, that's all.
Yes, I will be when they are done. Are you?
Yes, I will be when they are done. Are you?
Nope, as I'm not 100% sure that what I did absolutely "fixed" the problem and that I will never have to address the heads again.
I went with 100% all new head castings and components, etc. from the aftermarket, and I can't say that the problem is 100% "fixed", as for a fact, I don't know if the actual problem was corrected with my aftermarket heads, as I don't know what the actual problem is with the GM heads.
Apparently you know what the actual problem is with the GM heads if you are sure it will be 100% fixed after you are through. Care to share what the "real" problem is, so we can see if all those "theory's" being thrown around for the past 3-4 years are factual?
Your sharing of your knowledge could save the world of Z06 owners a lot of headaches and $$$$$ other wise spent on chasing false "fixes" being performed because of false "theory's" being thrown about and believed.
What do you know about the PRC265 heads with Ti intakes and SS exhausts with dual springs running on a stock cam with stock rockers, that is not "fixing" the problems with the GM heads you know all about, that makes you so confident that your "fix" is 100% and you will never have to address the valve problem again?
I'm sure not smart enough to make a blanket statement that my "fix" is 100%, but you seem to have no problem making the statement...
"Yes, I will be when they are done", when I asked "Are you certain your new heads are truly "fixed" and will give you no more valve problems in the future?."
Last edited by JoesC5; 08-31-2015 at 03:09 PM.
08-31-2015, 02:15 PM
#116
Melting Slicks
Not failures that I have read, but way out of spec ex. valves have reported under 20K miles after the fix. Not that most re check 10K or so miles later after getting theirs redone... so its a crap shoot I suppose.
08-31-2015, 02:24 PM
#117
Former Vendor
So is there a solution to bullet proof ls7 - last guy told me basically I need to check my guides and stuff every 10k miles despite having wcch stage 2 heads. (Bronze guides, solid stainless intakes - tumbled titanium exhausts) stock 70cc chambers have no idea what springs where used as vengeance racing is stupid and keeps records by first and last name so can't tell me **** about what the previous did - I only know from what he could remeber and what wcch could tell me from the serial number :/
Thanks for your kind words... Rest assured nobody at Vengeance "is stupid". We simply respect our clients privacy and do not share information without their permission. We are happy to tell you everything you want to know about your car IF our client calls and releases that information.
08-31-2015, 03:07 PM
#118
I think for a 16k motor the new customer should be informed about all the info about the vehicle, I mean what's confidential about giving a list of work being done to the vehicle now I understand asking for his or her number yea that's confidential. If I'm spending 50 60k on a used car I better get the info about it. I understand VR point of view but the new owner should be privileged to that information.
08-31-2015, 03:31 PM
#119
Former Vendor
I think for a 16k motor the new customer should be informed about all the info about the vehicle, I mean what's confidential about giving a list of work being done to the vehicle now I understand asking for his or her number yea that's confidential. If I'm spending 50 60k on a used car I better get the info about it. I understand VR point of view but the new owner should be privileged to that information.
08-31-2015, 03:35 PM
#120
lurking a LOT. Have 2008 Z OEm with 68K miles. no problems. Have not done a valve guide inspection--but will soon.
Im an experienced car guy--and I hear what is being said. But, I got to thinking--in all my years I have never heard of a bulletproof 7K rpm rather large engine, with over 500hp and a pisspot full of TQ that was? At the power level we are running all of them need careful attention.
Dont think GM has dropped the ball here guys. Could have been better---sure. Could have been bulletproof? Nope, dont think so.
By the way --Hey Vengence Guys--coming to see yall soon, getting ready to have a bit more fun!
Im an experienced car guy--and I hear what is being said. But, I got to thinking--in all my years I have never heard of a bulletproof 7K rpm rather large engine, with over 500hp and a pisspot full of TQ that was? At the power level we are running all of them need careful attention.
Dont think GM has dropped the ball here guys. Could have been better---sure. Could have been bulletproof? Nope, dont think so.
By the way --Hey Vengence Guys--coming to see yall soon, getting ready to have a bit more fun!