The case of the LS7 & LS9 Factory Heads and the Valve Drop Issue
Whether you ordered a 2005-2013 Z06 or a 2009-2013 ZR1 Corvette brand new, bought one used or are currently looking to buy one, you might have heard about the notorious "valve drop issues".
What is it?
To sum it up, there's many factors and theories. Heads machined improperly that resulted in valve guides not being seated concentrically in the head. The titanium coating on the valve stems wearing out too fast on the valve guides. Rockers allowing too much side play. The valve guides being too short for the longer valve stems. As such, once the stem snaps the valve drops onto the top of the piston. This results in at minimum minor damage to the heads and valve train. At most it is complete engine destruction from the oil pan to the plenum.
KaTech and Gwatney Performance lay it out quite well in these two links.
https://katechengines.com/pdf/183889
https://gwatneyperformance.com/ls7-valve-drop-issue-what-you-need-to-know/
What cars does it affect?
All 2005-2013 C6 Z06's having the LS7 heads and all 2009-2013 C6 ZR1's having the LS9 heads.
There's a lot of misinformation out there. Such as it only affects 06-08 C6 Z06's or 05-07's or 07-09's. It affects ALL of them. It is not a matter of if, it's a matter of when. Some of you will be lucky and it won't happen. Others will not be so lucky.
What do I do about it?
1.) Do nothing and just drive your car. You risk a minimum of $35K if you try to find another LS7 engine which is difficult because GM ceased production on these engines. That includes parts, labor and new heads. It's a gamble.
2.) Let your car sit and get new heads, intake and cam plus supporting hardware, gaskets, fluids and tune. $10K - $16K minimum for parts and labor depending on the shop.
3.) "Fix your heads". Ligenfelter and KaTech swear they've never had a failure of fixed heads. Others who had their heads fixed through other companies have reported a second failure.
4.) Go to YouTube and type in LS7 Valve Drop. There's plenty of videos talking about the issues. Watch them.
You can do nothing, you can fix your heads, you can replace your heads with fixed heads or you can get completely brand new aftermarket heads. That's 4 courses of action. Only YOU can decide what's best for you.
GM Knew About the Problem
https://www.solsticeforum.com/threads/a-sad-tale-of-greed-ls7-cylinder-head.168625/
Tip: If you go with aftermarket heads, you can sell your factory LS7 heads to Gwatney Performance Inc for $1,500. Just message them on facebook, instagram or send them an email on their website and they'll tell you the process. If the heads are not modified and in good condition with intake valves intact, they'll pay you the full $1,500. Just be sure to mark your heads so you can identify them and take pics of the top, bottom (valves) and sides from multiple angles in really good lighting so you have a visual record of what you sent them.
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