I have an LS7 in a 2006 z06 with what I would say is minor damage in cylinder #2.
Dropped an intake valve because I forgot to put lash caps back on after reinstalling the heads 😔.
There are 2 dings in the sleeve, no cracks. Probably too deep to overbore. But I'm wondering if possible to sleeve. Motor is otherwise fine.
Local machine shop says sleeving an LS7 always cracks...
Anyone with better news?

 

Find a different local shop!!! That is simply not true. BUT....As long as the aluminum block behind the sleeve is intact, you dodged a .44 mag bullet!! Steve at Race Engine Development @Steve - Race Eng has dry sleeves for this engine. Might be a bit pricey for shipping, depending on locale, but nobody does it better, and probably even as good. Shipping may actually cost more than sleeving only 1 cylinder, again, depending on location. Best of luck.....

 

BTW, until you know exactly why that valve dropped, it may not be your fault. Yes, that's a big error, especially if you put many miles on it without them. If you did, then it is probably on you. HOWEVER, if it did this within, oh, say only 25-50 miles, then it may not be on you. It may be just the LS7 being an LS7!! Counting on an LS7 having a reliable valvetrain is like counting on honesty and reliability in an ex wifes testimony at a custody hearing! Yes, I like that metaphor......

 

LS7 with block issues?? Nawwww.....
(Sorry, could not resist...)

 

Chances are the block is cracked behind the dented areas in the sleeve. Most likely can't be fixed. Unless you are local to me, not worth the cost of shipping it to find out. I've been replacing these cracked LS7 blocks with sleeved LC9 5.3 blocks. Much stronger casting.

 

Damn it, Gary!! Quit saying that, lol You gave me about the same quote.....Just because you're right, don't confuse us with facts!!!!!!!!

 

Got the sleeve out and of course you were right cracked behind the sleeve. A good local shop did it. They recommended loctite and darton single sleeve to fix it.
I'm trying to keep the original motor because it is a low mile car but if it's just lost cause give it to me straight. I'm in Newport News Virginia.

 

If they did sleeve it and it pressure tests okay, do you think it's just going to end up failing later? It's mainly just going to be a street car with occasional hpde or drag strip. Use. Stock cam no boost no Nitrous. But I also only want to do this once

 

I know you want to hear it will be OK if it passes a pressure test, but I'd listen to @Steve - Race Eng . He has forgotten more about this stuff than most guys will ever know. I would imagine there is a very small chance it would be OK. But unless you have really deep pockets, or just enjoy pulling the engine (some guys do, depending on their age), I'd give up on it. It may be OK for a year, or??? But with all the heat cycles, the flexing of the casting, etc., I dont see it being long term reliable. But, I've been wrong before......

 

That will leak with just Loctite. I don't think it can be successfully welded. When you weld that up it will most likely crack elsewhere in that bore on cool down or crack when the sleeve is installed. These blocks appear to get brittle with age. What I could weld up and repair a few years ago is no longer possible. Best to start with another casting. Any LS2, LS3 block can be sleeved also the already mentioned LC9 5.3 aluminum truck block.

 

Obviously not want I want to hear but I appreciate the advice and I'll start shipping

 

I ended buying an LC9 block which I had a local shop sleeve with darton sleeves and bore to 4.125. They're rebuilding the short block for me now.
I'll do the top end. I assume I need to use the dod delete plugs in the valley, can I use the stock LS7 valley cover?
Is there anything else significantly different between the ls7 and LC9 blocks? I'll be sticking with the factory dry sump system and I'm using the stock rotating assembly. Everything was still in good shape other than the one piston. Obviously using all new bearings and rings. Replacing the lifters.
Also installing the improved racing oil pan baffle.
I want to make sure I'm not missing anything

 

You’ll need to plug the dipstick hole in the block with a freeze plug, or you can pressure feed it with gray RTV from bottom of the hole, to the top. Other than that, everything else is the same on those two blocks…maybe consider using pipe plugs in the valley towers, which I do to all my stuff. Your machinist can do all of this for you. You’ve got a WAAAY better block under that car now with that sleeved LC9 than the LS7. Much stronger.

 

Do you mean hammering in plugs into the valley towers? Or tapping in plugs? Neither seems too difficult

 

I like to thread with a 1/4” pipe tap and use screw-in 1/4” pipe plugs personally…takes maybe a half hour. Lingenfelter makes a set that install like a pop-rivet, but I’ve never used them myself, so I can’t speak of their quality.

 

I have that kit Scott. I have used if for several years. No issues. Saves a lot of time. I deck the valley surface after installation of the rivets which may not be necessary but it looks a lot better.

 

I can say with 100% confidence that if Steve trusts it, it’s a quality product. Thanks for stepping in here Steve.

 

And that will fit under the ls7 valley cover?

 

Yessir. The LS7 block towers aren’t drilled for DOD…no holes in them. That’s why I mentioned tapping the towers and using plugs on the LC9 block. I’m not sure if your LS7 valley even has o-rings to seal the towers, because they weren’t ever drilled on that block. Might be a good time to grab an LS3 valley cover if your not planning on sealing off those towers with plugs of some sort. I personally don’t trust the valley o-rings alone, because o-rings can and will fail.

 

They fit fine, you just have to tap the hole deep enough to flush the plugs. I have done the rivets and the plugs, both work great, but I always do plugs on bare block builds just because you can remove them later for cleaning purposes. When you have an assembled or running motor that needs plugs, then the rivets are the only option.