Head work
12-12-2017, 12:10 PM
#21
Instructor
Mine were done by WCCH and have had about 4k miles on them since. I am also cammed though with some other work and it makes the typical sewing machine noise which on my other cars in my signature doesnt concern me but with this car it concerns me lol been reassured many times though that since my heads were done I should have no worries.
Last edited by docrocket1967; 12-12-2017 at 12:11 PM.
12-12-2017, 12:13 PM
#22
Safety Car
Of engines in service. Please let us know if you have better information.
Let me ask it this way. How many failures are you aware of? Round it to the nearest hundred.
Just in the Z06 and 427 Convertible, over 30,000 engines were produced. Most of them in the first four years. So unless you think the engine failures are over 300 (I do not), then the failure rate is less than 1%.
And we know the LS7 has been used in other applications also.
Let me ask it this way. How many failures are you aware of? Round it to the nearest hundred.
Just in the Z06 and 427 Convertible, over 30,000 engines were produced. Most of them in the first four years. So unless you think the engine failures are over 300 (I do not), then the failure rate is less than 1%.
And we know the LS7 has been used in other applications also.
I only personally know about 10 people with LS7 engines. Of those, 2 have lost engines when a valve broke. That's more than 1%. It's a small sample size.. but ask around.. I think you'll find other people in the car community have evidence that 1% is laughable for LS7 engine failure where the evidence points to a valve breaking first.
I also have dozens of friends hotrodding other engines and valves dropping without a valve spring (or retainer or keeper) failure first is close to 0% (Maybe one? Idk.. can't remember _any_).
Almost everyone who checks their guides on this forum finds them out of spec. Surely you can understand that a spec exists for a reason. That spec likely exists for multiple reasons. Loose guides or valve seats that are not concentric to the guide bore will put unnecessary side loading on the valve which likely will reduce its life. Is that one of the reasons for the spec? Seems reasonable to me. If you agree, then you have to acknowledge that you should have your guides checked.
It's "percent" not "per cent", btw.
12-12-2017, 12:34 PM
#23
Team Owner
Cars with valve guides beyond GM's service limit with only 10, 15, 20K miles (etc.) are considered a failure in my book, when the car shouldn't be seeing tolerances like that until 100K+. Its not complete catastrophic failure...but the wait and see approach is just plain ill-advised.
12-12-2017, 10:06 PM
#24
Safety Car
As far as the work that was done they used CHE bronze guides, Ferrea hollow stem exhaust valves, I supplied new OEM titanium intake valves, Manley springs with tool steel retainers and 10-degree keepers. We also installed aftermarket push rods and then on the install we put in CHE rockers I got from WCCH. I'm totally sold on the LME package for head fixes.
The following users liked this post:
12GaugeZ06 (12-20-2017)
12-12-2017, 10:25 PM
#25
Race Director
I used to defend your methods but your refusal to accept aggregated data from this community means you're just stubborn and lack objective analysis. Please stop quoting 1%. That's GM's number and is not supported by the failures reported on this website alone.
I only personally know about 10 people with LS7 engines. Of those, 2 have lost engines when a valve broke. That's more than 1%. It's a small sample size.. but ask around.. I think you'll find other people in the car community have evidence that 1% is laughable for LS7 engine failure where the evidence points to a valve breaking first.
I also have dozens of friends hotrodding other engines and valves dropping without a valve spring (or retainer or keeper) failure first is close to 0% (Maybe one? Idk.. can't remember _any_).
Almost everyone who checks their guides on this forum finds them out of spec. Surely you can understand that a spec exists for a reason. That spec likely exists for multiple reasons. Loose guides or valve seats that are not concentric to the guide bore will put unnecessary side loading on the valve which likely will reduce its life. Is that one of the reasons for the spec? Seems reasonable to me. If you agree, then you have to acknowledge that you should have your guides checked.
It's "percent" not "per cent", btw.
I only personally know about 10 people with LS7 engines. Of those, 2 have lost engines when a valve broke. That's more than 1%. It's a small sample size.. but ask around.. I think you'll find other people in the car community have evidence that 1% is laughable for LS7 engine failure where the evidence points to a valve breaking first.
I also have dozens of friends hotrodding other engines and valves dropping without a valve spring (or retainer or keeper) failure first is close to 0% (Maybe one? Idk.. can't remember _any_).
Almost everyone who checks their guides on this forum finds them out of spec. Surely you can understand that a spec exists for a reason. That spec likely exists for multiple reasons. Loose guides or valve seats that are not concentric to the guide bore will put unnecessary side loading on the valve which likely will reduce its life. Is that one of the reasons for the spec? Seems reasonable to me. If you agree, then you have to acknowledge that you should have your guides checked.
It's "percent" not "per cent", btw.
Please do your research before you try to correct me. Percent and per cent are both acceptable. And after the post you wrote, do not get me started on criticizing your writing.
Last edited by Tonylmiller; 12-12-2017 at 10:27 PM.
12-12-2017, 11:45 PM
#26
So estimate how many have failed. Your guess is as good as mine. I have not seen anything that indicates over 300 failures.
Please do your research before you try to correct me. Percent and per cent are both acceptable. And after the post you wrote, do not get me started on criticizing your writing.
Please do your research before you try to correct me. Percent and per cent are both acceptable. And after the post you wrote, do not get me started on criticizing your writing.
Tony before this zr1 z06 topics merged. I had a sticky who did your heads and what oils were being used. Now tube list was long very long; like stated above when the tolerant are out of spec when pulled that's considered a failure correct. Not catastrophic but a failure but unacceptable on a 100k car..so to the conclusion we are not at NASA and in engineering school we are just trying to help you if you do your research on my builds in on my 2 build..goodluck.... Tony
12-13-2017, 12:00 AM
#27
Instructor
I guess you have to decide if you want to take the chance that it will be your Z06 that drops a valve. I went with AHP Stage 4 with MS90 guides.
I couldn't be happier. Zero issues. I did the swap myself and I used this link:
https://www.corvetteforum.com/forums...-headswap.html
A picture always says a thousand words:
https://www.google.com/search?q=ls7+...w=1920&bih=970
I couldn't be happier. Zero issues. I did the swap myself and I used this link:
https://www.corvetteforum.com/forums...-headswap.html
A picture always says a thousand words:
https://www.google.com/search?q=ls7+...w=1920&bih=970
12-13-2017, 07:18 AM
#28
Its all about taking the "good, well informed" advice off this forum and not the "poor, misinformed".
Point is.... HAVE THEM CHECKED! Whats the harm in that???
12-13-2017, 08:23 AM
#29
Race Director
Tony before this zr1 z06 topics merged. I had a sticky who did your heads and what oils were being used. Now tube list was long very long; like stated above when the tolerant are out of spec when pulled that's considered a failure correct. Not catastrophic but a failure but unacceptable on a 100k car..so to the conclusion we are not at NASA and in engineering school we are just trying to help you if you do your research on my builds in on my 2 build..goodluck.... Tony
12-13-2017, 08:31 AM
#30
Race Director
I guess you have to decide if you want to take the chance that it will be your Z06 that drops a valve. I went with AHP Stage 4 with MS90 guides.
I couldn't be happier. Zero issues. I did the swap myself and I used this link:
https://www.corvetteforum.com/forums...-headswap.html
A picture always says a thousand words:
https://www.google.com/search?q=ls7+...w=1920&bih=970
I couldn't be happier. Zero issues. I did the swap myself and I used this link:
https://www.corvetteforum.com/forums...-headswap.html
A picture always says a thousand words:
https://www.google.com/search?q=ls7+...w=1920&bih=970
Some factors to consider:
- Nobody needs a car with the LS7 engine. It is a luxury. Do you want to spend extra money on your car? I have no problem with that. It is your car and your money.
- Are you willing to accept risk? Are you financially able to withstand the cost of a new engine?
- How much is "peace of mind" worth to you? Although "fixed" heads sometimes fail, too.
- I think the failure rate would have to be about 10% to make financial sense to proactively "fix" your heads. That would be 3,000 engine failures. Surely no one claims that many.
- I am not a person who tends to worry, and I can accept the risk. I might rework my heads someday anyway. Who knows?
12-13-2017, 08:42 AM
#31
Race Director
I guess you have to decide if you want to take the chance that it will be your Z06 that drops a valve. I went with AHP Stage 4 with MS90 guides.
I couldn't be happier. Zero issues. I did the swap myself and I used this link:
https://www.corvetteforum.com/forums...-headswap.html
I couldn't be happier. Zero issues. I did the swap myself and I used this link:
https://www.corvetteforum.com/forums...-headswap.html
12-13-2017, 10:12 AM
#32
Safety Car
You've been told multiple times that there is no way to come up with an absolute number. If it were possible, I'd be willing to bet $2500 that the failure rate is nowhere close to 1%. 
12-13-2017, 10:43 AM
#33
Race Director
Of course, I'm sure you know much more about this than the people who designed, built, service, and handle the warranty claims on these vehicles. That makes perfect sense to me. Not really.
12-13-2017, 12:29 PM
#34
Wrong that is not a success....maybe in your book but you have your opinion just like you stated...good luck I just wont continue to argue about this when you don't know the facts and give people misinformed information on here....plain and simple don't take a chance its not that its going to happen its when its going to happen...
12-13-2017, 01:01 PM
#35
Team Owner
I do agree with you that every owner should be well informed to inspect their own car, and make their own informed decision on next steps based on those inspection results.
You are probably correct. By the way, do you think it is 10%? You seem to have an opinion as to what it is not, but no opinion about what it is.
Of course, I'm sure you know much more about this than the people who designed, built, service, and handle the warranty claims on these vehicles. That makes perfect sense to me. Not really.
Of course, I'm sure you know much more about this than the people who designed, built, service, and handle the warranty claims on these vehicles. That makes perfect sense to me. Not really.
My "gut" feeling based on what I know/read/see/hear...I would estimate "catastrophic" engine failure to be in excess of 10%.
If we are calling premature guide wear a failure (as I do), meaning one or more guides beyond GM tolerances at 50K miles or less (unacceptable life span for this to occur); I would say it affects nearly every LS7 produced.
12-13-2017, 01:06 PM
#36
Of engines in service. Please let us know if you have better information.
Let me ask it this way. How many failures are you aware of? Round it to the nearest hundred.
Just in the Z06 and 427 Convertible, over 30,000 engines were produced. Most of them in the first four years. So unless you think the engine failures are over 300 (I do not), then the failure rate is less than 1%.
And we know the LS7 has been used in other applications also.
Let me ask it this way. How many failures are you aware of? Round it to the nearest hundred.
Just in the Z06 and 427 Convertible, over 30,000 engines were produced. Most of them in the first four years. So unless you think the engine failures are over 300 (I do not), then the failure rate is less than 1%.
And we know the LS7 has been used in other applications also.
Your still saying its under 1%? Really? lol I know 3 z06 owners local that have dropped a valve...My head guy has seen many an hundreds out of spec in low miles, and hes just one porter
You sound like most people on this forum back in 09 10 back before people believed guides were wearing in less than 10k miles.
My own heads out of spec with headers an cold air, I had AI rework mine to be out of spec again...You should look at the z06 fb page...at least a motor a week has dropped a valve an I've only been on the site 2 years. I remember my porter saying that 75% would be out of spec by 25k miles 8 years ago...he was wrong its higher than that.
Also how many heads had guides out of spec an were saved like this nice exhaust valve. now this wasn't an engine failure yet. But i'd be willing to bet it wouldn't have lasted another 1000 miles
To the op get them at least checked look how lucky this guy was
Last edited by 2fastz06; 12-13-2017 at 01:57 PM.
12-13-2017, 07:51 PM
#37
Safety Car
You are probably correct. By the way, do you think it is 10%? You seem to have an opinion as to what it is not, but no opinion about what it is.
Of course, I'm sure you know much more about this than the people who designed, built, service, and handle the warranty claims on these vehicles. That makes perfect sense to me. Not really.
Of course, I'm sure you know much more about this than the people who designed, built, service, and handle the warranty claims on these vehicles. That makes perfect sense to me. Not really.
12-13-2017, 08:03 PM
#38
Race Director
Nor do I, yours...but to each his own again. I call it luck, nothing more. The failure occurred upon assembly of an engine that wasn't capable of a normal lifespan within the manufacturers recommended tolerances.
I do agree with you that every owner should be well informed to inspect their own car, and make their own informed decision on next steps based on those inspection results.
Before anyone could hazard a guess, we would have to agree on what a failure actually is, and we simply do not.
My "gut" feeling based on what I know/read/see/hear...I would estimate "catastrophic" engine failure to be in excess of 10%.
If we are calling premature guide wear a failure (as I do), meaning one or more guides beyond GM tolerances at 50K miles or less (unacceptable life span for this to occur); I would say it affects nearly every LS7 produced.
I do agree with you that every owner should be well informed to inspect their own car, and make their own informed decision on next steps based on those inspection results.
Before anyone could hazard a guess, we would have to agree on what a failure actually is, and we simply do not.
My "gut" feeling based on what I know/read/see/hear...I would estimate "catastrophic" engine failure to be in excess of 10%.
If we are calling premature guide wear a failure (as I do), meaning one or more guides beyond GM tolerances at 50K miles or less (unacceptable life span for this to occur); I would say it affects nearly every LS7 produced.
12-13-2017, 08:39 PM
#39
Team Owner
12-13-2017, 08:52 PM
#40
Race Director
Well, I will admit that it is a little annoying that you think I'm wrong, but you do not state why, or what you think the failure rate is. And why we should believe you over Chevrolet. What information do you have?
Last edited by Tonylmiller; 12-13-2017 at 08:55 PM.