Corvette Z06 Forum banner

1 - 20 of 21 Posts

·
Registered
Joined
·
562 Posts
Damn, that can't be good for the valves...how do those look?

I guess that's what to expect from a 242/248 - .608/.612 on a freggin 110 LSA :eek: HUGE!
 

·
Registered
Joined
·
2,375 Posts
Killa,

Ouch!!!!!!!!!!!!

You are looking at the kiss of death and I think you need more than shims. If you are going to run that cam you may need to fly cut your pistons. With the amount of "Kiss" in the photo's you probably bent some valves also. I would think something like this may have been making noise hence pulling your heads after work. Good luck on your repair. I guess the T-REX instructions are correct when it says check valve to piston clearance. Are you running the Comp 921 spring with your cam?

It may be worth the effort now to do a clay test and see what your clearance is. Couldn't hurt anything at this point.

D.J.
 

·
Registered
Joined
·
79 Posts
Look at the small white lines on the pistons where the valves kissed the heads! It says not enough piston to vlave clearance for that cam, especially on a 110 Centerline.

CobraKilla, how did that thing run with the 110 CL?
 

·
Registered
Joined
·
999 Posts
2002Z06Yellow said:
can someone please explain what the picture says?

The combination of the high lift and the high duration of the cam holds the valve open such that when the piston is at the top of its exhaust stroke its hitting a valve. Note the small cressant shaped indentions in the upper left area of each piston (the last photo shows them the best). Not good.

JWz06.
 

·
Registered
Joined
·
17,744 Posts
WOW! DIY piston notching, not good. :cheers:
 

·
Registered
Joined
·
2,375 Posts
Vette1171 said:
my guess is -.08 :p
The comment about the clay test was in reference to the shim statement in his post. I was thinking out loud that he may be thinking it was caused by weak valve springs or not at the correct installed height. I would think that during the cam degreeing process you might feel this type of contact when you manually roll over the engine. Maybe not.

D.J.
 

·
Registered
Joined
·
36 Posts
Discussion Starter · #10 ·
The car isn't mine, I'm just changing the heads, trans and rear end for the owner. The car had the cam for 10k miles or so I think actually. The car laid down 45xrwhp 3 weeks ago and pulled strong enough to break the rear end and trans Friday night. But yes we're going to have to figure out what we're going to do about it. I also didn't install the cam in the car so I don't know if there was any interfernce before or not.
I'm thinking that when the broke the rear end (in 1st gear at WOT) it lost forward motion and hit the limiter hard. Plus a few other times the car's seen the limiter just caused it to float the valves and get into it.
There was no noise coming from it, the car ran quite and the only reason we pulled the heads is we're supposed to put different ones on it. Anyway I gotta run for now I'll check back later.
-Brad
 

·
Registered
Joined
·
2,375 Posts
:jammin: Thanks McRat. Now theirs some info I can use. Did you run a vacuum or what ever when you made the cuts? How much did you remove? Inquiring minds want to know.

D.J.
 

·
Registered
Joined
·
204 Posts
Killa and I are working on that car. The "kissing" happened at high rpm's, most likely when he hit limiter. We are shimming the springs for better high rpm valve control. The car ran very strong. It should be up and running in the next 2 weeks. We are waiting on the trans and rear end to show up.
-matt
 

·
Registered
Joined
·
1,280 Posts
OneQuickCoupe said:
:jammin: Thanks McRat. Now theirs some info I can use. Did you run a vacuum or what ever when you made the cuts? How much did you remove? Inquiring minds want to know.

D.J.
I brought the piston to TDC and taped off the the bore. I used the 2.125"(? I'll check when I get home) intake cutter and went .090" deep. Vacuumed chips, and removed tape.

I didn't do the exhaust as it had tons of room.

When you are done, put a light spring on the valve, torque the head with the old bolts, and check clearance with a dial indicator. Max interference is about 10 deg ATDC if I remember right.
 

·
Registered
Joined
·
2,375 Posts
McRat,

At 10 degrees is the intake valve chasing the piston down the bore? Is that the closest postion in the piston to valve relationship?

D.J.
 

·
Registered
Joined
·
109 Posts
Anyone know what the CC is on the stock 10.5:1 comp LS6 heads?
 

·
Registered
Joined
·
1,280 Posts
OneQuickCoupe said:
McRat,

At 10 degrees is the intake valve chasing the piston down the bore? Is that the closest postion in the piston to valve relationship?

D.J.
It will depend on your cam ramps, but yes. The valve out accelerates the piston on it's way down. This is because the piston doesn't move down very fast until about 30 deg.
 

·
Registered
Joined
·
895 Posts
I've got about 6000 miles on my TRex install, with (knock on wood) no problems or funny noises to date. I had the rev limiter moved to 6800.

Also have COMP921 springs as well. Heads have NEVER been off the engine.

Steve
 

·
Registered
Joined
·
2,127 Posts
smithsc said:
I've got about 6000 miles on my TRex install, with (knock on wood) no problems or funny noises to date. I had the rev limiter moved to 6800.

Also have COMP921 springs as well. Heads have NEVER been off the engine.

Steve
1-If you never had the heads off then the valves are stock size. AFR heads have larger valves which adds to the problem.
2- if you are running same C/R then you didn't mill the heads.
I had to do it cause I had larger vaves and milled the heads and after crunching the number I had .037 clearance on paper.
Comp cams wants .080-.100 P/V clearance.
 
1 - 20 of 21 Posts
Top