1988Bullitt

If everyone on here has not heard enough about LS7 cylinder heads here is one more story…
This winter I planned to finally take my stock 2006 Z06 and start modifying it. The plan was a supercharger, headers and tune. First I decided I needed to check the valve guides before I started the build. I am not one to buy into the “internet hype” but man am I glad I checked the heads!!!
History on the car, I am the second owner. I purchased my Z in the summer of 2011 with 12,500 miles on it. The car was perfect and completely babied; it didn’t even have a rock chip. Every engine bolt had the factory paint mark in place and nothing had been touched. The car currently has 34,000 miles on it. It is my good weather daily driver; I have done one track day in Nashville, about 8 trips to the drag strip in Bowling Green and yearly trips down to Deals Gap, NC. I drive the car spiritedly but I also take very good care of it. The only modifications are a K&N cold air and Mild to Wild exhaust.
The car runs great, had what I would consider a normal level of valve train noise. The car uses hardly any oil (maybe ½ a quart between oil changes) I use 5w-30 Mobil 1 and AC Delco filters every 3,000 miles. There were no indicators I had any issue at all, my teardown was purely for inspection purposes before the supercharger was installed. What I found surprised me to say the least…
I purchased the COMP 5462 spring compressor, which worked fantastically and started pulling springs off. My shop and the engine was about 55F when taking these measurements.
Cylinder #2 Intake .007 Exhaust .005-.006
Cylinder #4 Intake .008 Exhaust .005
Cylinder#6 Intake .0075 Exhaust .005
Cylinder #7 Intake .007 Exhaust .005 Pictured below was something I was very surprised to see. #7 Intake spring seat and stem seal is completely destroyed. It’s smashed, in two pieces and the seal is completely gone. Because of this I plan to pull the oil pan and inspect for debris. Again, this engine ran perfect, I had no idea this had happened.
Cylinder#5 Intake .008 Exhaust .006
Looking in the workshop manual production spec is .001-.002, with service spec being .003*. So it looks like I will be pulling the heads at a minimum. I love this car and I have no problem “paying to play” but I am disappointed in the wear my heads show and the failure that it may have lead to if not addressed. I understand this is a performance vehicle but for a stock, 34,000 mile car this type of valve guide wear and the spring seat damage should not have occurred.
Checking guide clearance:

Good stem seals and spring seat:


My #7 intake stem seal and spring seat, compressed and broken in two pieces:


Spring locks seem to be mushroomed or damaged. I am surprised considering these should be very hard and brittle metal… (No tools used to remove these, just the compressor and a magnet so it’s not tool damage)



Started the complete teardown, now I just have to transfer it over to my lift and drop everything else.

DON T.

The good news is you found it JUST in time. So your not out a complete motor! The answers you need are here on this forum for head fix, unless you take a diff route. Good luck with new build and show us the finished product..

DaOtherOne

1988Bullitt

I have read a lot, which I guess can be dangerous . I will be calling PRC/Texas Speed and WCCH tomorrow and getting their recommendations.

Dirty Howie

My original motor in my 08 broke a spring seat. Car ran and sounded fine. Found out because parts were stuck to my magnetic drain plugs. Motor later failed


DH

'06 Quicksilver Z06

Good move.

GeneSch

I am ordering a blower this week to put on my 10,000 mile 06Z and I think im just going to pull the heads and do it now while I still have a chance. If you dont mind posting what they recommend it will save me and them the time. Im going to stick with stock cam as well and just add some boost.

MTIRC6Z

Probably your first call should be to American Heritage, they not only actually sponsor this forum but have also directly made many very valuable contributions to the membership about how to best rebuild LS7 heads

Cheers, Paul.

Yankee15

At least give Kohle at AH a call. That parts free!
You won't regret it.

solodogg

damn, didn't expect to see yours come up with this issue. If you need a hand with the build, LMK

Unreal

If you plan on a blower you may want to just do the pro or other aftremarked heads for a thicker deck and 6 bolt option. Otherwise wcch and prc are two great options.

1988Bullitt

Thanks everyone for all the information. I have been out of town for the past two weeks for the holiday and work. I hope to pull the motor this weekend if I get a chance. I still have not had a chance to call anyone on the heads but I appreciate the other options suggested. I will keep the thread updated as I make progress.

1988Bullitt

May I ask how much your head work was?

Dirty Howie

You seem very happy with your head work


DH

DON T.

Damn, that's beautiful. looks familiar.

reasonable suspicion

No porting?

Dirty Howie

Looking forward to your update when that happens


DH

DON T.

That is crazy when one thinks about it. Damn motors are bullet proof one minute and then fragile the next.

1988Bullitt

I had a free afternoon Saturday to tear the car mostly down. I still plan to pull the engine and check that the oil pan and oil pump pickup are clean. Heads are on their way to Texas speed.

1988Bullitt

Thanks Brett, I plan to drop the front subframe this weekend, you are welcome to stop by and have a beer. It will be good practice for your C6.