Z28 valve guides LS7 issue?

[Shark72]

Originally Posted by FASTFATBOY

The reason you can't find anything on this forum is the Z28 carries a very small fraction of the 427's.


Want to learn about the valve issues? Go read on Corvetteforum.com

Exactly!
Drive it like you stole it, and don’t worry about it!

[FASTFATBOY]

Originally Posted by Shark72

Exactly!
Drive it like you stole it, and don’t worry about it!

I'm thinking you haven't seen what a dropped valve does to an engine. More often than not it's a total loss.


You won't go to a junkyard and find an LS7 like you will and LS1, 2, 3.


When it happens it's a $10-15,000 ordeal

[Shark72]

Originally Posted by FASTFATBOY

I'm thinking you haven't seen what a dropped valve does to an engine. More often than not it's a total loss.


You won't go to a junkyard and find an LS7 like you will and LS1, 2, 3.


When it happens it's a $10-15,000 ordeal

As a matter of fact, I have seen the damage done…
What’s your point!

[richard grimsley]

If my experience is of any use, after the purchase of my “15 Z, I checked the valve stems. Found 7 were out of tolerance an 3 excessively out. Pulled the heads and had Lingenfelter repair/ upgrade. In the meantime, I checked cam, then bearings, then…. etc. Story shortened, I ended up having to have the Ls7 built.

Merely my thoughts and based off of my experience, get them checked. If something is not of specifications fix and replace before the Ls7 becomes a nightmare -boat anchor and or bad memories.

[highrevving]

So GM did not correct issue after 2011.

Hate to see this on the mighty LS7. Now we have to rebuild our engines in less than 100k.

One of the reason I got this Z was the historic connection to the racing C6R.

[macalot]

It is a Small Block Chevy, enough said. Run it hard, but within suggested boundaries and enjoy! Been doing that since 1973.

[booboo37]

I just put a couple sets of Ls7 heads and blocks in the for sale section...

[FASTFATBOY]

Originally Posted by macalot

It is a Small Block Chevy, enough said. Run it hard, but within suggested boundaries and enjoy! Been doing that since 1973.

Bad info, the LS7 has a very well known valve/valve guide issue that destroys the engine completely when a valve drops, it is not your typical "small block Chevy"

[FASTFATBOY]

Originally Posted by Shark72

As a matter of fact, I have seen the damage done…
What’s your point!

My point is, saying that without knowing how real this issue is is giving out bad info. On the Facebook Z06 pages these heads are constantly being done and redone to avoid the well known valve dropping issue the LS7 is known for.


This info is all over Corvette Forum in the C6 Z06 section.



When a car comes up for sale on the C6 Z06 pages the first question is "have the heads been fixed"


Just because the LS7 is in a Camaro does not change this fact.


Read up


https://www.google.com/search?q=Do+a...h=703&dpr=1.25

[FASTFATBOY]

Originally Posted by highrevving

So GM did not correct issue after 2011.

Hate to see this on the mighty LS7. Now we have to rebuild our engines in less than 100k.

One of the reason I got this Z was the historic connection to the racing C6R.

No, they didn't correct it. All LS7's have this issue. From what I have read the valve seat is not concentric with the valve guide and the guide is too short for the longer valve in the LS7.


There are 3 types of LS7's



One that the valve has dropped in


One that the valve is waiting to drop


One that has had the heads "fixed" and will require the same "fix" in the future(factory head).


I'm not sure even aftermarket heads fix this issue 100%.

[highrevving]

[QUOTE=FASTFATBOY;11162276]No, they didn't correct it. All LS7's have this issue. From what I have read the valve seat is not concentric with the valve guide and the guide is too short for the longer valve in the LS7.

Thanks for the info.

Have you checked your Z28's valve guides?

[macalot]

All I know is I'm running mine the way it is. If I drop a valve I'll be right on this forum letting you all know that one has finally been confirmed. 12,000 miles so far, with a hand full of track days. Have a great day!

[FASTFATBOY]

[QUOTE=highrevving;11162599]

Originally Posted by FASTFATBOY

No, they didn't correct it. All LS7's have this issue. From what I have read the valve seat is not concentric with the valve guide and the guide is too short for the longer valve in the LS7.

Thanks for the info.

Have you checked your Z28's valve guides?

I do not own one and won't own one(an LS7), when I was doing track days in a 99 Z28 I did a lot of reading and research on a C5 vs a C6 Z06 for track days as that was my next step in a track car. The things that I found kept me out of the C6 Z06 because of the engine issues. I bought a C5 Z06.



You blow up a LS6 you can put a new one back in the car for 5K, you blow up a LS7 it's 10-15K. Most track guys if they blow up an LS7 put an LS3 back in the car due to cost and longevity.


My track days are over and I am in a 5th gen ZL1 and love it.

[highrevving]

Thanks for the comments.

I knew the risk of riding this horse. Just could not pass up a chance to own this American GT3RS with heritage from C6R. And I'm coming from owning bunch of Japanese/German performance cars.