Ls7 heads dropping valves
Thread Starter
Joined: Apr 2004
Posts: 430
Likes: 0
From: West Palm Beach, FL
Ls7 heads dropping valves Have any vendors experienced a "bad" batch of stock ls7 heads? Over on cf, there's a bunch of guys that are dropping exhaust valves. Kinda making me a little concerned as my car has the (what has been determined "normal") ticking between 1500-2500 rpm. I'm suspecting that there is something amiss with the rocker geometry causing excessive valve guide wear but don't have any real evidence.
I was hoping some venders could shed some light on this.
I was hoping some venders could shed some light on this.
Staging Lane
Joined: Aug 2012
Posts: 65
Likes: 0
I can tell you that my 07 dropped a valve. I can also tell you I haven't seen outside of 06-08 cars do it. Also a thread popped up recently on cf claiming it was a manufacturer problem in the geometry of the valve tunnel in the heads themselves.
Trending Topics
My guides were all wore and out of spec on the exhaust side. Richard at WCCH redid my heads and is pretty confident it's a heat issue on the exhaust valve and it's cooking the oil and gauling the valve and thus wearing out the guide. The stock valves are also 2 pieced and sonic welded at the head of the valve. There also has been some shown to be very inconsistant in the stem thickness after cutting them open. Get new bronze guides put in and get those sodium filled stockers out and all will be fine 
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
if you read through all the CF threads, this is happening but it's not a catastrophic failure of ls7 engines. probably 1% of all engines having issues and most of the issues are coming up on cammed cars.
Staging Lane
Joined: Aug 2012
Posts: 65
Likes: 0
My guides were all wore and out of spec on the exhaust side. Richard at WCCH redid my heads and is pretty confident it's a heat issue on the exhaust valve and it's cooking the oil and gauling the valve and thus wearing out the guide. The stock valves are also 2 pieced and sonic welded at the head of the valve. There also has been some shown to be very inconsistant in the stem thickness after cutting them open. Get new bronze guides put in and get those sodium filled stockers out and all will be fine
Higher lift cams would exacerbate the problem above. More lift means more travel which means more heat.
Staging Lane
Joined: Aug 2012
Posts: 65
Likes: 0
TECH Regular
Joined: Jan 2010
Posts: 449
Likes: 0
From: Bay Area
Fran which would you do:
1. Have WCCH do their Stage 2 package heads with the SS valves, comp cam 3/8 7.800 push rods, trunion upgrade, and manley springs with reused stock intake valves
Or
2. Buy Texas Speed PRC 285cc heads with titanium intake/SS exhaust valves
If there's any changes to any of those setups feel free to chime in
1. Have WCCH do their Stage 2 package heads with the SS valves, comp cam 3/8 7.800 push rods, trunion upgrade, and manley springs with reused stock intake valves
Or
2. Buy Texas Speed PRC 285cc heads with titanium intake/SS exhaust valves
If there's any changes to any of those setups feel free to chime in
Thread Starter
Joined: Apr 2004
Posts: 430
Likes: 0
From: West Palm Beach, FL
Thanks for taking the time to respond. In your opinion, what is causing the excessive valve guide wear?
AWD if it were me, and it might be soon. I think aftermarket casting might be the way to go. It would completely rule out any geometry issues stock LS7 heads might have. Not sure if there is even a problem, but something is definitely wearing out the valve guides
AWD if it were me, and it might be soon. I think aftermarket casting might be the way to go. It would completely rule out any geometry issues stock LS7 heads might have. Not sure if there is even a problem, but something is definitely wearing out the valve guides
I agree with your cause more than the whole geometry issue. I think GM changed the oil pump to the higher flow rate ZR1 pump in 09 but never revealed it. Jason from Katech at one point even stated that the sprocket on the Z06 from 09 on was that of the ZR1. Doesn't make much sense to only change the sprocket and re-engineer the oil pump to fit the new sprocket.
Higher lift cams would exacerbate the problem above. More lift means more travel which means more heat.
Higher lift cams would exacerbate the problem above. More lift means more travel which means more heat.
There was some speculation that the LS7 got the LS9 pump after 2009, but it wasn't the case. The LS7 still gets the same pump that it did in 2006. The crank sprocket changed in 2009 to accommodate the thicker pressure section of the LS9 pump and rather than continuing to make two sprockets they just made the one sprocket go on both engines since it fits on both. A 2009 crank sprocket will fit with a LS7 oil pump, but not the other way around.
To answer the OP, there is nothing wrong with the LS7 exhaust valves. There is a frenzy of people on the Corvette Forum who refuse to accept that conclusion, but we are continuing to use them in racing engines that we have to stand behind and we do not see a problem. We are seeing excessive guide wear (intake and exhaust) on LS7 and LS9 (especially with higher lift camshafts) which we are continuing to gather data on, but we do have a fix that we are doing for any track-going car which is bronze guides and our titanium/molybdenum intake valves.
Launching!
Joined: May 2010
Posts: 274
Likes: 1
My guides were all wore and out of spec on the exhaust side. Richard at WCCH redid my heads and is pretty confident it's a heat issue on the exhaust valve and it's cooking the oil and gauling the valve and thus wearing out the guide. The stock valves are also 2 pieced and sonic welded at the head of the valve. There also has been some shown to be very inconsistant in the stem thickness after cutting them open. Get new bronze guides put in and get those sodium filled stockers out and all will be fine