[Z06] Another dropped valve.
#41
Melting Slicks
#43
Melting Slicks
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St. Jude Donor '12
you must not have read the same thing I did. they stated only two failures on their dyno, not two total failures. how many failed off the dyno months later? how many are about to fail? how many would have failed if heads were not redone before they failed?
#44
As posted above in bold, the argument is officially over.
No more posting.
Thank you "vertC6" for ending this argument.
When you gettin your Z?
#45
Burning Brakes
Texas Speed both your heads worked, new bronze guides and SS valves for the sodium filled time bombs, ported $1200.00 you pay shipping. That's to great of a price to pass up.....
My 2 cents
JwT
My 2 cents
JwT
#46
Safety Car
So many questions - so few concrete answers. Such is life. But it looks like there are two things we ALL can agree on: there is premature guide wear with stock motors and an increased risk of catastrophic failure in otherwise modified engines. This is, likely totally a game changer!
Oh yeah, and it looks like most all of us agree that the odds of failure are less than 1% even with modified vehicles. But yeah, if it worries you have the valves and guides swapped out for less than the cost of a warranty extension.
#47
Melting Slicks
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St. Jude Donor '09-'11
http://forums.corvetteforum.com/1581566412-post83.html
#48
Melting Slicks
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St. Jude Donor '12
How many Z06 owners will die before their valves drop? How many more will die while waiting for the heads to be shipped back from a vendor? How many will have some other problem, like spinning a bearing, after getting the heads reworked (I know of at least one)???
So many questions - so few concrete answers. Such is life. But it looks like there are two things we ALL can agree on: there is premature guide wear with stock motors and an increased risk of catastrophic failure in otherwise modified engines. This is, likely totally a game changer!
Oh yeah, and it looks like most all of us agree that the odds of failure are less than 1% even with modified vehicles. But yeah, if it worries you have the valves and guides swapped out for less than the cost of a warranty extension.
So many questions - so few concrete answers. Such is life. But it looks like there are two things we ALL can agree on: there is premature guide wear with stock motors and an increased risk of catastrophic failure in otherwise modified engines. This is, likely totally a game changer!
Oh yeah, and it looks like most all of us agree that the odds of failure are less than 1% even with modified vehicles. But yeah, if it worries you have the valves and guides swapped out for less than the cost of a warranty extension.
#49
Melting Slicks
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St. Jude Donor '12
Lou just clarified this: "The ONLY two that have failed, have been on the dyno..."
http://forums.corvetteforum.com/1581566412-post83.html
http://forums.corvetteforum.com/1581566412-post83.html
#50
You can bet more than two. Heck LG probably doesn't even know about some blown LS7 with their cams in them. It's not just LG though, there are many different cam producers out there who's cams have been in blown engines. I'm sure those companies know of some, but not all of the failures with their product, but of coarse the aren't eager to tell us, probably not too good for business .
It's too hard to keep an accurate count of blown engines.
#51
Former Vendor
The list of total dropped valves, is less than 5, with OUR customers.
Mike W, dallas Tx- STOCK Z, dropped valve at barber. He bought wheels and slicks.
Preacher- Dallas tx (Cant remember his name) Not our cam, he was the third owner- dropped valve on dyno, he bought a new crate engine, and we put our cam in it.
Tom- Alabama- race car- one piece stainless ex valves, bronze guides, stock intake valves- dropped ex valve, paperweight engine ( may this year)
Tom, houston, our cam, we did all the work, 19k miles. Dropped on dyno last week.
Mike W, dallas Tx- STOCK Z, dropped valve at barber. He bought wheels and slicks.
Preacher- Dallas tx (Cant remember his name) Not our cam, he was the third owner- dropped valve on dyno, he bought a new crate engine, and we put our cam in it.
Tom- Alabama- race car- one piece stainless ex valves, bronze guides, stock intake valves- dropped ex valve, paperweight engine ( may this year)
Tom, houston, our cam, we did all the work, 19k miles. Dropped on dyno last week.
#52
Burning Brakes
Would you care to commment some more...
#53
Melting Slicks
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St. Jude Donor '12
The list of total dropped valves, is less than 5, with OUR customers.
Mike W, dallas Tx- STOCK Z, dropped valve at barber. He bought wheels and slicks.
Preacher- Dallas tx (Cant remember his name) Not our cam, he was the third owner- dropped valve on dyno, he bought a new crate engine, and we put our cam in it.
Tom- Alabama- race car- one piece stainless ex valves, bronze guides, stock intake valves- dropped ex valve, paperweight engine ( may this year)
Tom, houston, our cam, we did all the work, 19k miles. Dropped on dyno last week.
Mike W, dallas Tx- STOCK Z, dropped valve at barber. He bought wheels and slicks.
Preacher- Dallas tx (Cant remember his name) Not our cam, he was the third owner- dropped valve on dyno, he bought a new crate engine, and we put our cam in it.
Tom- Alabama- race car- one piece stainless ex valves, bronze guides, stock intake valves- dropped ex valve, paperweight engine ( may this year)
Tom, houston, our cam, we did all the work, 19k miles. Dropped on dyno last week.
by the way, until Michelin grows a set and sells you tires they will not have to worry about selling any to me. I hope the courts side with you.
#54
Safety Car
Lou just clarified this: "The ONLY two that have failed, have been on the dyno..."
http://forums.corvetteforum.com/1581566412-post83.html
http://forums.corvetteforum.com/1581566412-post83.html
#55
Former Vendor
The valve weight isnt a concern, as they are relatively light all things considered.
The valvespring, seats and retainers are all race grade PSI cup based stuff. There was 1500$ in just seats, springs, retainers, and locks. Not the standard comp 921 road going parts. They were all intact, and they were all well within spec pressure wise. The cam is standard issue G7xx, marine based lobes, very gentle on parts.
#56
Safety Car
The list of total dropped valves, is less than 5, with OUR customers.
Mike W, dallas Tx- STOCK Z, dropped valve at barber. He bought wheels and slicks.
Preacher- Dallas tx (Cant remember his name) Not our cam, he was the third owner- dropped valve on dyno, he bought a new crate engine, and we put our cam in it.
Tom- Alabama- race car- one piece stainless ex valves, bronze guides, stock intake valves- dropped ex valve, paperweight engine ( may this year)
Tom, houston, our cam, we did all the work, 19k miles. Dropped on dyno last week.
Mike W, dallas Tx- STOCK Z, dropped valve at barber. He bought wheels and slicks.
Preacher- Dallas tx (Cant remember his name) Not our cam, he was the third owner- dropped valve on dyno, he bought a new crate engine, and we put our cam in it.
Tom- Alabama- race car- one piece stainless ex valves, bronze guides, stock intake valves- dropped ex valve, paperweight engine ( may this year)
Tom, houston, our cam, we did all the work, 19k miles. Dropped on dyno last week.
Did the cars with Stainless exhaust valves have dual springs too?
#58
The list of total dropped valves, is less than 5, with OUR customers.
Mike W, dallas Tx- STOCK Z, dropped valve at barber. He bought wheels and slicks.
Preacher- Dallas tx (Cant remember his name) Not our cam, he was the third owner- dropped valve on dyno, he bought a new crate engine, and we put our cam in it.
Tom- Alabama- race car- one piece stainless ex valves, bronze guides, stock intake valves- dropped ex valve, paperweight engine ( may this year)
Tom, houston, our cam, we did all the work, 19k miles. Dropped on dyno last week.
Mike W, dallas Tx- STOCK Z, dropped valve at barber. He bought wheels and slicks.
Preacher- Dallas tx (Cant remember his name) Not our cam, he was the third owner- dropped valve on dyno, he bought a new crate engine, and we put our cam in it.
Tom- Alabama- race car- one piece stainless ex valves, bronze guides, stock intake valves- dropped ex valve, paperweight engine ( may this year)
Tom, houston, our cam, we did all the work, 19k miles. Dropped on dyno last week.
#60
Former Vendor
Any idea of how many LS7`s your shopped has worked on over there years? and I read a post on the other thread where your shop has spent tens of thousands with a cylinder head engineer to try and fiqure out this problem? why would you if it is just a few examples and a small percentage?
Ive broken every single part, in an LS1, LS2, LS3. Of those, We have never Broken an exhaust valve. We have been racing LS engines since 1999, and we've failed a lot of parts. Broken cranks, broken rods, melted pistons, broken pistons! turned lifters, stuck cams, spun bearings, pushed water, cracked blocks, cracked main caps, broken timing chains, worn cam thrust plates, the list goes on.... We.have.a.lot.of.experience.racing.these .engines. Period.
We will determine a root cause, but it may take a bit.
The good thing is that there are a lot of fixed knowns. We know the valve height of all the LS7s, we know the rocker ratio of all the LS7s, we know the pushrod length, angle, cam lobes, guide material, guide length, seat angles and material....etc...
We will work on a formal write up, and although we have already started testing solutions, but this will document everything in hopes of fortifying the LS7, because it is such a great piece of work.
Louis