pkincy

Well definitely PM me when you get here. I can't imagine a better place to own a Corvette, which is why I have two. <g>

Mopar Jimmy

I would buy it and quit reading the forum. I WOULD NOT buy it if your going to be worrying about it having a major engine issue everytime you are driving it (b/c driving scared is not fun and its just not worth IF you are driving worried all the time).

I myself think the C6 Z is a great car and the engine issue is overblown on the forum, but the car certainly has a larger percentage of engine issue versus other high performance street cars and the dropped valve issue was always in back of my mind (even though I had 2 more full years of GMPP bumper to bumper warranty).

What year Viper do you have? I just bought a 2009 Viper Coupe VOI 10 and LOVE it and traded my C6 Z in for it 2.5 weeks (it was just time for a change for me and the valve issue was a small factor in my decision even with my warranty).

3 Z06ZR1

25,000 Z's produced and maybe a few hundred with that we know about blown. Of that amount some had different cams and springs.
Over blown to "just change the valves to be safe" I consider my 43,000
miles blown Z with stock heads nothing to worry about. With a super quiet heads. I even run without the covers. Still very quiet.

GMuffley

That's misleading. I doubt that a majority of Z06 owners visit this site; we don't know how many of those cars have had issues.

Mark2009

Yes and no. For example:

It is misleading, not because it is low but because it is high -- we actually know about only a few dozen engines that have blown because of valve issues. These tend to get lumped in with all the other engines that have blown because of other issues, mostly the oil starvation failures on race tracks (which was addressed by the larger oil tank on the '09 and up models).

Now we do know of a few hundred here with worn guides. While worn guides are bad, it is a matter of degree as to whether or not it will cause a broken valve. So far I'd say that maybe 10-15% of the worn guide cars have dropped a valve. Will the other 85-90% of the worn guide cars drop a valve? I'd say there is a good chance they will if the guides wear to a certain point (unknown what point that is) and/or if the car is driven very hard (like on a race track).

The upside is that the guide issue can be addressed by simply rebuilding or replacing the cylinder heads. So it's a two step deal with the LS7: first, have the guide wear checked. Second, if the guides are worn, plan on getting them replaced -- ASAP if they are worn badly, in the not too distant future if they aren't too far along. Or just get them replaced up front without checking anything, but you may be wasting money and if substituting aftermarket parts you may be putting in something that doesn't work as well as the OEM stuff (or as well as the OEM stuff was supposed to work... if the guides are wearing prematurely then there is obviously an issue with execution at the OEM level).

Based on what we've seen reported here on the forum the odds of having worn guides are pretty high... 50% or better, if I had to put a number on it, and that's probably conservative. And before anyone asks (again ) the only way definitive to tell is to remove the valve springs and check the stems with a dial indicator. Exhaust smoke, noise (clicking-clacking-tipping-tapping), oil consumption, oil on spark plugs, leak down test, none of that is a reliable indicator. Best thing to do is budget up front for getting the guides replaced; if you get lucky, then so much the better

GM claims to be on the lookout for this problem on heads made on/after Feb. 2011... I'd give that about a 50% chance of being worth the screen it was typed on (there is no official GM document stating such, and a subsequent official GM document indirectly claims the valve guide issue is an internet myth).

So, are OEM heads destined to fail? Not all of them... that's blown out of proportion. Better check, though.