LS9 valve guides
 

Dont tell me this is a issue with the ZR1. How many of you guys have swapped out heads?
Have 12k miles, will not be tracked, do i really need to worry about this. Some say yes, some say the LS9 is bullit proof, my Lord

Perhaps it is either in part a combination of the guides and valves? The LS9 uses slightly smaller Del West Ti intake valves than the LS7 uses, and had the same CrN coating prior to the point in time where Del West started tumble polishing their Ti valves. GM approached Del West when they were designing the LT4 and asked them to see if they could make their Ti valves any smoother. Del West proposed the additional step of tumble polishing the valves, and GM liked it so much they even began to apply the process to all the Ti valves they had in inventory for GM. Some machine shops like AHP will actually send out the older Ti valves that they inspect and approve for reuse, and Del West will apply this tumble polishing process to them, as well.

Who knows for certain if the issue is as bad as it is on the LS7, but the thing about valve guides are by the time you go through all the work to pull the heads and accurately measure your guides, you may as well rebuild/freshen up the heads while they are out, (great time if nonetheless to replace the lifters as you can only do that with the heads off.) AHP has a great new CNC porting program now for the LS9 cylinder heads so even if you kept the same OE cam and just do Johnson SLR 2110 lifters/ new pushrods, and AHP CNC ported heads with Moldstar 90 beryllium-free copper valve guides, PSI valve springs, and the additionally tumble polished Ti intake valves, you're going to pick up some good power on top of increased durability and reliability.

https://www.corvetteforum.com/forums...post1598859036

Thanks, im on here everyday, and im just reading on this issue involving the LS9.

John, in case you haven't seen my reference/compilation thread....the attachment therein contains links to actual CF reports. Gary


https://www.corvetteforum.com/forums...on-the-cf.html

I certainly hope that the LS9 doesn't have the same issues with machining/rough stems on the Ti valves, and start dropping them like the LS7. If this does happen, it'll be a disaster for owners in the short term, and for GM in the long run......

Katech has done extensive research on LS 7/9 heads and concluded: “Katech’s independent research has not limited the issue to 2008-’11 models; but rather all LS7s and LS9s 2006-present.”

Advance search CF or Katech for more.

Mine were out of spec at 6k miles and at 12k miles

C7 LT engines have the same issue.

Yup - Katech has a video I've seen thru FB on the LT4 - same crap. Stock will last longer, add more lift and it increases your wear rapidly

I have spoken with John, Matt at 21st Century Motorsports here in Dallas.. They have been working on and building the C6ZR1 since 09... They have came across ZERO valve guide issues w LS9... Not my opinion, This came from 21st...

bringing back from the dead...

That's what I wanted to hear😁

I think we will run into issues eventually but not as bad as with the ls7s, they made the heads in a different place and it's a different setup. Ls3's don't seem to be dropping valves daily either

Yup ... This valve problem don't exist on the LS3, however the LS3 don't have titanium valves ... The LS3 uses hollow stainless steel intake and solid stainless steel exhaust valves.

And the valve guides last forever.

Early valve guide wear is an issue on LS9 heads as well as LS7 heads.
With that said it is no where near as prevalent on LS9 heads as it is on LS7 heads.
The 1.8 rockers on the LS7 sure help point out issues that are present alot faster than the 1.7 rockers on the LS9 heads. Another school of thought is that the LS7 and LS9 both share titanium intake valves that were processed/manufactured in the same manner (two different valves but same process). The process GM used on the LS7 and LS9 intake valves left an incorrect stem finish that can contribute to early valve guide wear. GM corrected this processing/manufacturing issue on the LT4 titanium intake valves.


https://americanheritageperformance.com/

Been saying the above in bold for a long-long time, the different rocker arm ratio (higher) is not good and adds to side wear. Takes me back to my old Mustang 5.0L days, stock 1.6 ratio, everyone was putting on 1.7 roller rockers, more lift/free hp but more wear.

Jeeeze ... I am hoping that 1.8 ratio rocker arms don't eventually destroy the valve guides in my LS3.

This weekend, I am installing a set of Comp Cams 'Ultra-Pro Magnum' 1.8 rocker arms, PAC springs and hardened Brian Tooley pushrods.


https://www.cnc-motorsports.com/medi...apromagnum.jpg

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apparently the coating isn’t the inherent problem then, since the lt4 has the same valve guide premature wear issue.

The coating is the problem - they just attacked it wrong thinking polishing would fix it. The issue with CrN comes from no oil retention as the PVD coating is applied too perfect. There is nowhere for oil to hide and protect the parts from wear. Polishing doesn’t help that. What does help is using a moly coating or switching to a totally different valve stem material. Most all valves use hard chrome on the stem for wear protection which has microscopic cracks in it that oil can hide to keep lubricated. Once the chrome started to be applied by PVD instead that went away.

perhaps you should let gm know