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C6 Corvette ZR1 & Z06General info about GM’s Corvette Supercar, LS9 Corvette Technical Info, Performance Upgrades, Suspension Setup for Street or Track
Throughout the years on here I've read that there has been wiggle tests that were bad, but I've never read that a stock zr1 dropped a valve, and I know there's a lot of higher mileage zr1's out there now.
The ls7 and ls9 have different heads, they're not designed the same way. I'm sure every shop wants zr1 owners to do their heads now too
It'd be nice to actually know though cause it's a great excuse for me to pull my heads off and add more power 😂
Last edited by chubbs6350; 02-01-2021 at 08:54 AM.
Lol- yeah. The zr1s are interesting in terms of falling into 2 main groups
1- low mileage examples which haven’t been driven much
2- modded with heads and cam
i would think the one way to get any insight From group 2 would be to poll the guys on Kong s face book group (Zr1 everything) and see of the modded guys checked their heads when they pulled them.
2020 Corvette of the Year Finalist (performance mods)
C4 of Year Winner (performance mods) 2019
Originally Posted by chubbs6350
...but I've never read that a stock zr1 dropped a valve, and I know there's a lot of higher mileage zr1's out there now...
Mine's at 60K miles now on stock heads. Stock engine for that matter, only within the last few thousand miles has it had any mods and those are all "bolt-ons".
So it looks like this is a LS9 issue too. Here I was thinking it was an ls7 issue only. The other thread mentions the lt4 too. Why is this such an issue for GM?
If you download the attached list (in post #1), and follow the referenced links, you will come across specific information for each report (if provided therein by the poster of that report).
The measurements have all been all different; each car is different.
If you download the attached list (in post #1), and follow the referenced links, you will come across specific information for each report (if provided therein by the poster of that report).
The measurements have all been all different; each car is different.
yeah I tried three of them, none had actual guide to stem measurements.
2020 Corvette of the Year Finalist (performance mods)
C4 of Year Winner (performance mods) 2019
So just to be clear, per the spreadsheet we have two (2) reported cases of dropped valves on LS9s. One of those (poster has a grand total of 2 posts on the forum) and in his 2nd post clarified that the spring broke and retainer popped off, so I'm not sure I'd classify that as the same issue as the LS7. This leaves us with one reported issue of valve drop on the LS9. Beyond that is looks like 22 reported cases of valve train wear outside of spec. Even if we count the ones where someone saw a "failed" head at a shop, out of 4684 ZR1s made we have less than 0.5% that have been reported here with valve train issues.
mirage2991, I did post measurements with the report on my own car. There are others on the list that have done so, but I agree you do need to hunt for them...
EvanZR1, that is all of the data I've been able to collect from the C-F thus far. Unfortunately (IMO), the sample size isn't representative of the universe of C6 ZR1s,
as it is likely that not all C6 ZR1 owners are C- F members. I am not sure that "sample" difference can be meaningfully addressed when looking to compare relevant statistics.
I do not have all of the answers. All I can conclude is that the matter should not be ignored.
Thanks again to all for their input.
Last edited by Gary '09 C6; 07-02-2021 at 04:58 PM.
Reason: sp & formatting
I asked for the measurements when I sent the heads in to be worked on. The service limit on the guide to valve stem clearance is .0037" , a few of my intake valves were up to .0058". They had a decent amount of wiggle when I checked. Would they have failed? I don't think anyone can say yes or no to that question, but they were above the service limit, so I had work done to them.
I asked for the measurements when I sent the heads in to be worked on. The service limit on the guide to valve stem clearance is .0037" , a few of my intake valves were up to .0058". They had a decent amount of wiggle when I checked. Would they have failed? I don't think anyone can say yes or no to that question, but they were above the service limit, so I had work done to them.
mine were checked by ecs here in in NJ and were out .0052 - .0054. I had them removed. Waiting for the work to be completed.
So I will be having my car modded in the near future. While the supercharger is removed can someone give me an idea of how much a shop would most likely charge to measure and inspect my stock heads?
02-01-2021, 07:10 AM
