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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
I was having second thoughts on getting an LS7. I was under the impression that the problem was widespread.
Thanks for a reality check.
Except he is completely wrong.
I've met plenty of people at shows that never heard of this forum, that were on motor #2 or 3. It is very widespread.
And besides other corvette owners, the #2 worst thing about owning a vette is the dealers. You can't depend on them to change the oil, let alone fix a head. Unless it is under warranty, a corvette should never go back to a dealer (few exceptions like Abel).
I do my own work, as do many here, so my heads come off once a year for inspection and refreshing.
Is that with stock LS7 heads? I was under the impression that with aftermarket heads (Such as the PRC265's I have ) that it's, for the most part, no longer an issue. So I wouldn't think they need to keep being checked.
Not so much factory GM casting vs aftermarket, as overall setup of complete valve train. Just because you have PRC heads doesn't mean anything.
It is an overall system. Cam, lifters, springs, etc. More aggressive cams, more spring pressure, etc will wear guides faster. Guides are a wear item, they wear out. Its like saying once you switch to Michelins you never have to look at tires again. That depends on how you drive, use, alignment, suspension, weather, road conditions, etc.
Not so much factory GM casting vs aftermarket, as overall setup of complete valve train. Just because you have PRC heads doesn't mean anything.
It is an overall system. Cam, lifters, springs, etc. More aggressive cams, more spring pressure, etc will wear guides faster. Guides are a wear item, they wear out. Its like saying once you switch to Michelins you never have to look at tires again. That depends on how you drive, use, alignment, suspension, weather, road conditions, etc.
Obviously things still wear and more aggressive setups will wear faster, etc. But how does having PRC heads (Or any of the aftermarket head for that matter... WCCH, AI, etc) not mean anything when it fixes the problem?
I am just saying I don't think you have to keep opening her up and looking every year once the heads are "addressed" and the initial GM problem is "fixed" (assuming it was a proper fix and the valvetrain was installed/setup properly). Not that it would hurt, but it's not like every engine with aftermarket heads and/or a cam needs to be inspected every year.
If a particular tire had a manufacturing error that caused ruptures or blowouts, that problem would be addressed if you switched to a tire that didn't have the problem. Of course that doesn't mean the new tire won't still be subject to wear.
Aftermarket heads are potential part of a solution, but not a solution on their own. They can wear just as fast.
Tech, just trying to put it into something people would understand. Yes they should get a good 100-120k miles, or on some cars, last longer than the motor. On a 1.8 rocker, aggressive cam, high pressure, high RPM setup, that may not be realistic.
As Unreal said, the guides and other parts of the valve train (springs, retainers etc) are wear items depending on setup and usage. If you are lugging around town with an occasional highway blast, the wear will take virtually forever to occur (once the initial fix is in place). Same for garage queens, show cars etc (nothing wrong with this). Mine is raced, so just like the tires, brakes, clutch etc will wear, so do the guides and parts of the valve train due to my setup and how I use the car. My heads are off my car right now in fact for a refresh. May go with a different rocker this time around (shaft mount roller).
I replaced springs at 22k miles. Inspected guides, inspected rockers, etc. For a high performance high RPM car, this is normal if it is used as intended.
Aftermarket heads are potential part of a solution, but not a solution on their own. They can wear just as fast.
Tech, just trying to put it into something people would understand. Yes they should get a good 100-120k miles, or on some cars, last longer than the motor. On a 1.8 rocker, aggressive cam, high pressure, high RPM setup, that may not be realistic.
Things like this make me happy I switched to a baby cam with the gentle EPS lobe profile.
And yeah, if you race the car, have really aggressive setups, etc, you'd need to check more often. But for most of us, the problem is fixed with heads.
In my case it's a baby EPS cam, stock RPM, 510rwhp setup...and it's just a street car. Never see's the track. Driving style = mostly cruising, will drive semi aggressively here and there and occasionally get on it ***** to the walls. (I think that's probably most of us). Guessing the engine shouldn't need a peek for at least another 50k miles or so...maybe even 100k miles. And since I'll only drive it 1-2 days a week and it sits all winter, that is virtually forever, lol.
You have a very safe, reliable setup kbreese. And 510 rwhp is no slouch. I bet that thing pulls like hell, and power delivery is probably very smooth/predictable with good street manners. She will likely last a long, long time with no issues or worries.
Due to how I drive mine, and the semi-aggressive setup for track work, I must pay more attention to all of the moving, rubbing parts (as well as others here). My clutch decided to give up the ghost a few weeks ago at the track (no surprise as it wears), and I wasn't happy with my latest Blackstone report. So rather than wait until the off season to thoroughly inspect the heads again I just decided to take the car out of commission for a month and refresh them while swapping in a new clutch,slave, master etc. May add some new parts as well for the hell of it. "Since I'm already in there again..." kind of stuff. Was hoping I made it to the winter for this refresh as I just had her apart a few months ago for the new manifold, TB etc...but such is life and race cars. **** wears and breaks. Here she is now.
You have a very safe, reliable setup kbreese. And 510 rwhp is no slouch. I bet that thing pulls like hell, and power delivery is probably very smooth/predictable with good street manners. She will likely last a long, long time with no issues or worries.
Thanks Mordeth, appreciate it. And yeah, it's smooth linear power delivery with excellent street manners. Idles very similar to what I have heard stock ones idle, and will chug along at low rpms no problem at all. And yes, to me it does pull like hell. VERY fast street car for sure, at least in my book. It has over 400wtq starting @ 2200 rpm. You just give it a little bit of gas and the car is effortlessly flying forward equivalent to a normal car romping on the gas. Not that it's not controllable...you know what I mean...
It's great that you have the time and abilities to work on your car like that...and great that you use it as it was meant to be used!
I'll be pulling the PAC 1209 springs out of my MMS 265 heads around the 15k mile mark and replacing them if needed. I will check guide wear as well, hopefully things will be within tolerance with the PM guides that TFS installs, along with the SS valves that Tony fits in them. Mine is a solid roller so I waived my right to a set it and forget it valvetrain when I made the decision to go SR. IMO no LS7 is a dead nuts set it and forget it valvetrain...don't feed them after midnight, and for the love of god don't drip water on them.
Wrong, no, bad advise, don't listen... How many more ways can we say this, over and over again?
DON'T BUY A CAR WITH AN LS7 UNLESS YOU CHECK THE VALVE GUIDES, PERIOD - END.
That is all, sheesh..
Uh no you are wrong. Less than 1% affected. That is a known fact. You people on here are unbelievable. You make it sound like 25% of them blew up. It is comical. I am a member of the largest Corvette club in the entire US. You know how many Z06 owners in the club knew about this so called wide spread valve issue, not one.
OP, if you want to have them checked for peace of mind by all means. But do not listen to the nonsense on here that it is running rampid through all LS7's. Funny, Motor Trend, Car and Driver, Road and Track and all the smaller syndicates have been racing and tearing upthese LS7's on a track since 2006. How many dropped a valve? LOL
Uh no you are wrong. Less than 1% affected. That is a known fact. You people on here are unbelievable. You make it sound like 25% of them blew up. It is comical. I am a member of the largest Corvette club in the entire US. You know how many Z06 owners in the club knew about this so called wide spread valve issue, not one.
OP, if you want to have them checked for peace of mind by all means. But do not listen to the nonsense on here that it is running rampid through all LS7's. Funny, Motor Trend, Car and Driver, Road and Track and all the smaller syndicates have been racing and tearing upthese LS7's on a track since 2006. How many dropped a valve? LOL
This guy sounds like he is friends with that other guy, the one that claimed "it must be related to the area of the country, the dealership I visit in the North East hadn't heard about it..".
One more time, to the OP - here are the REAL facts..
1. Over 80 percent of the heads checked for guide wear on this forum were found to have one or more guides out of spec. Not 1 percent, or 10 percent, eighty percent..
2. Loose valve guides are the number one LS7 block ventilation / $16,000.00 paper weight creating contributor.
3. Unless you like to gamble, you'd be a fool not to check them.
Anyone advising you to "don't worry, just drive it!", ask them if they will they put their money where their mouth is - will they write you a $16,000 check? The silence will be deafening.
Last edited by Dan_the_C5_Man; 06-22-2017 at 12:20 PM.
They have? You mean a couple hours of testing for each publication? Not sure that qualifies as a big testament to the whole valve issue.
A couple hours of testing (minimum), at full throttle over 7 years and how many syndicates? Yea I would call that a decent sample size with zero issues. Thanks. LOL
A couple hours of testing (minimum), at full throttle over 7 years and how many syndicates? Yea I would call that a decent sample size with zero issues. Thanks. LOL
It's not the same exact car used over that 7-year span. They are given a new or almost new car in perfect ready-to-go condition from GM for a few hours of performance testing at best.
These are merely quick performance tests of new vehicles, not reliability tests.
If you have 100 different sydicates all doing long term torture or endurance testing for 10k-50k miles, that would be different. But that's not even remotely the case.
06-21-2017, 10:03 AM
And yeah, it's smooth linear power delivery with excellent street manners. Idles very similar to what I have heard stock ones idle, and will chug along at low rpms no problem at all. And yes, to me it does pull like hell. VERY fast street car for sure, at least in my book. It has over 400wtq starting @ 2200 rpm. You just give it a little bit of gas and the car is effortlessly flying forward equivalent to a normal car romping on the gas. Not that it's not controllable...you know what I mean... 
