C6z 2007

[Alstoy]

Looking at 2007 C6Z with 31000 km. Heads checked 2000 km ago and all valves are in spec.
Runs good doesn't burn oil. PO has changed rocker arms to reduce side loading on valves.
Has anyone heard of this ? Will it help?

 

[Roughrider]

Maybe call an engine rebuild shop, they will probably give you an answer.

 

[Rruuff Day]

Looking at 2007 C6Z with 31000 km. Heads checked 2000 km ago and all valves are in spec.
Runs good doesn't burn oil. PO has changed rocker arms to reduce side loading on valves.
Has anyone heard of this ? Will it help?

I agree with Roughrider. From what I have read on the LS7 issue, it appears to be a rocker arm failure problem so would guess that new rocker arms before they give grief should help. My concern would be replacing with OEM rocker arms as if this is indeed the source of the problem, it may come back in the future. I would definitely call either Dave at RaceReadyGarage in Cambridge Ont. or Steve at Davenport Motorsports in Calgary Ab. and ask the question. These guys have done lots of LS7 heads. JMO

 

[Maximus]

I thought it was a valve guide issue. never heard anyone swaping out rocker arms to fix the inherent LS7 head issue

 

[Rruuff Day]

I thought it was a valve guide issue. never heard anyone swaping out rocker arms to fix the inherent LS7 head issue

There has been some discussion regarding rocker arm and needle bearing failures which may lead to the valve guide wear.

 

[Alstoy]

The theory as I understand it is that rocker arm geometry is wrong allowing the rocker arms to put side pressure on the valve stem as it opens the valve. This would result in excess wear on one side of the valve guide resulting in an oval valve guide. New rocker arms are engineered to reduce side pressure and therefor solve the uneven valve guide wear. Some shops are saying that they have not had any returns on engines that they have changed the rocker arms. I believe that usually they use a roller rocker to do this. It does make sense to me.

 

[Maximus]

hmmm. so why have all the re valve guide engines lasted?

 

[Rruuff Day]

hmmm. so why have all the re valve guide engines lasted?

Maybe they changed out the rockers as well... If not, a "re valve guide" engine will only last as long as the original..... There are lots of LS7 engines out there with a ton of miles that haven't had this problem. No easy explanation...