AzMotorhead

Mods you can move this to the appropriate topic.
I searched and there were just too many threads to go thru.
AHP got my heads apart and here are the measurements
This was done with a bore mic gauge.
Valve Stem OD: .31360"


#1 intake
T .0040"
M .0021"
B .0052"

#3 intake
T .0061"
M .0035"
B .0092

#5 intake
T .0060"
M .0031"
B .0079"

#7 intake
T .0034"
M .0019"
B .0036"

#1 exhaust
T .0014"
M .0015"
B .0036"

#3 exhaust
T .0013"
M .0015"
B .0029"

#5 exhaust
T .0013"
M .0015"
B .0031"

#7 exhaust
T .0015"
M .0017"
B .0034"

#2 intake
T .0040"
M .0022"
B .0031"

#4 intake
T .0034"
M .0019"
B .0030"

#6 intake
T .0065"
M .0025"
B .0080"

#8 intake
T .0050"
M .0023"
B .0055"

#2 exhaust
T .0014"
M .0015"
B .0023"

#4 exhaust
T .0014"
M .0014"
B .0018"

#6 exhaust
T .0024"
M .0015"
B .0034"

#8 exhaust
T .0013"
M .0014"
B .0031"

My 2009 Z06 has 21300miles on it. Generally weekend cruiser with a few hard driving sessions on it.
AHP is doing the Heads and Cam K501(?)
I must saw Kohle and the rest of the crew at AHP have been great at keeping me apprised of the process and going round and round with the extended warranty.

Dirty Howie

How did your heads sound?
Any oil consumption?
Were you just being cautious or did you do a Wiggle Test or were you in there to do a Cam.


DH

Dan_the_C5_Man

Yeah, those clearances blow.

Others should follow your lead - AHP rocks.

LFZ

It probably would have blown up on the next start up.

FNBADAZ06

You doing any milling on the heads, Phil ?

Dan_the_C5_Man

Nope, but ONLY because the intakes were way out - if those numbers were on the exhaust side, damn skippy!

LFZ

Yes I know

MTPZ06

You're in good hands with Kohle. He did my '09 C6Z heads last year when I was local. If its mainly a weekend cruiser...K501 might be a bit much. Depends on what sort of "street manners" you're looking for I suppose.

AzDave47

In a couple of months I'll be able to report my stock 09Z variances at about 47K miles and some good track work. I wouldn't be surprised if they were similar to OP's. Actually overall the exhaust valve clearances did not look that bad, in spec just barely in a few cases.

Mrfitter

I was up in the air about redoing my heads but decided to do them anyway. I had AHP send me some heads with the new heads and my 2011 stock motor 6000mi heads side by side my old heads had major visible wiggle on all of the intake valves the exhausts were solid. AHP heads no wiggle solid. I'm now a believer of if you don't have a warranty to get them done.

AzMotorhead

I did a wiggle test at about 13k and knew there were a couple that were close then. So I took it in right before my GMPP expired.
I probably had some consumption but never really recorded it.

Not going to mill them just resurface. Our gas is crap here and I dont want to search for E85 of 100LL.

BTW I do some HPDE's & would like to do a bit more. Kohle suggested the next hotter cam up from the 116. He hasn't told me exactly which cam it is yet, but Kohle has said with the Head& port work Cam & tune its produces 585-600 hp. I'm assuming thats at the crank.

Unreal

Strongly suggest a milling. Even with "crap" gas it will help significantly and no need for e85/etc.

Michael_D

And I'd strongly advise against milling with crap ga, unless all you give a shiit about is 1520' runs. I've been dealing with engine builds in my area with 90 octane for over twenty years. You have to sacrifice too much spark in too many areas for it to be worth it.

I would however suggest using a .040" gasket. You will pick up substantial gains in overall performance tightening quench. Downside to this, is that I love the OEM gaskets on these engines, and am not as confident in the aftermarket.

Hib Halverson

"Michael D" (as is often the case) is absolutely right. With "crap gas" (what ever that is) and even with 93-oct, you're going to get KR at WOT high-load anytime the air-density is good.

With a stock LS7 the CR is already quite high. if you increase the CR, you're going to get even more knock retard.

The spark retard will cost you more in performance than will leaving the CR as is.

Now, if your tracking the car and always using 100-oct unleaded, then mill, baby, mill!

AzMotorhead

I'm not always tracking the car, but when I do I generally run 100 Octane.
Bad thing is Most times I have the car out ambient air temps are 80+ and that's measured in the shade away from pavement. and highest octane you can find at the pump is 91
SO since I live here in H377- (Phoenix) I'm holding off on milling

Unreal

As someone that has tuned and messed with a lot of cars here, milling is an easy 20-30rwhp more, and takes 1-1.5 degrees less timing at WOT. So you run 19 degrees instead of 20, but get 20-30rwhp more, and power everywhere. Well worth it.

Dale1990

Just curious, how much milling are we talking about? .020", .030", more?

Unreal

Depends on your end goal.

20-30. If you are concerned with "crap gas" you can go on the lower end. I've always had people do 30 and never had anyone complain or have issues.

Michael_D

Below are screen shots of two high spark timing tables. Both are 2008 Z06's. I tuned both cars. Similar power levels of both. Well, potential anyway. All other spark tables are the same, cause that's just the way I do things. Target PE AFR is 12.5 for both, same engagement parameters. AFR spark correction tables are all zero'ed out.

One is my personal car. One is a friend's car. I can only get 90 octane. He can get 95. I still fight KR, off idle and transient fueling, even with the spark where it is. I can throw more spark at my friend's car, and it'll take it. I stopped raising it, because there is no point to go higher.

My friend is using a .040" gasket. I used the OE gasket. Same stock CC volume, same swept volume, same valve reliefs.

So go ahead and take Unreal's advice and mill away, without any consideration to your fuel. Or, take a look at these tables and decide if you really think that's a good idea or not. I'm not going to argue this point further.

Unreal

Or listen to someone in Arizona, that has done this tons of times, and tons of other locals that are all happy, making more power, more torque, and running plenty of timing on 91 with a .030 mill. One guy even recently commented he wished he did a .045".

I can go dig up two high spark tables from local Arizona cars, one unmilled, taking ~21 degrees peak or so, the other milled taking ~19. The really difference is the dyno charts because the one taking 2 degrees less timing makes 25rwhp more with the same cam.

So do whatever you want, but in my experience, in Arizona, milling is well worth it. The trade off of running 1-2 degrees less timing is well worth the added benefits.

And I am taking in consideration octane, which is why I'm saying 20-30, not 45+ on milling.