Georgies

Hi all,

one of my spark plug holes is damaged and i want to fix it properly and take off the heads. also get a general look at the cylinder bores and maybe port the heads. Id rather not mill them if its not needed. the motor has about 25k miles on it.

its a 2003 z06.

From what i understand, milling the heads would increase compression ratio and on boosted motors you want low compression? If thats the case, should i not mill them if not needed?

I was going to order LS9 head gaskets but thought i should ask here first before attempting the job myself. at the same time want ARP head studs.

What do you all think i should do? any part#s would be appreciated too.

I plan on going twin rear sometime within the next 2 years.

Thanks

ascastil

What casting number heads do you have?
I'm running LS9 gaskets and ARP studs. No complaints, it's working lol.

DBS99MagRedCoupe

At a minimum I would upgrade the valve springs, pushrods and rocker arm trunnions. Make sure to order the correct set of studs for your year engine. Ensure all of the coolant is out of the bolt holes before you install the studs.

Georgies

Ive already done CHE trunions, pac dual springs, manton 3 piece pushrods, titanium retainers, ls3 timing chain, high pressure oil pump etc...

How do i know what studs to get?

StatmanRN

I think its always a good idea to surface the heads while they are off, in your case just the minimum to true them.
Regardind studs, you cant go wrong with the ARPs- but they will cost you.

Turpid porpoise

You should have the Pre '04 long and short style head bolts. In 2004 they changed to all "short" bolts.

Georgies

how can i confirm this?

Smoken1

When you remove the heads, the 2 end ones in the center row will be the shorter ones

Turpid porpoise

You have a 2003 Z06, confirmed to be Pre 2004.

junk c5

I’d deck the heads so they’re 100% straight at whatever the material loss. You can always use a thicker head gasket to even the compression back out. A head that’s not straight will push head gaskets with boost .

Georgies

Ok that sounds logical. So ill get it done. What head gasket brands offer a thicker option for this type of scenario?

Smoken1

The LS9 head gaskets are thicker than stock...
My heads had .005 taken off just to clean then up so I could keep the compression lower using the LS9 gaskets

junk c5

That would take some research. Look into the thicknesses available for LS9’s and contact Cometic and see what they have available for your application.

junk c5

https://www.lingenfelter.com/product...62SPP075S.html

Georgies

thank you!!

Georgies

Considering im running a ms4 cam that i know isnt good for boost. Is it.wise to lower compression that much??

junk c5

I ran a MS4 and it wasn’t great but it’s what I already had at the time. What fuel are you running ? IDK what kind of cylinder pressure that cam would produce. I’d consult a cam guru like Patrick G or LJMS.

Georgies

This is what my compression test got.

Georgies

What type of forced induction?

junk c5

I had a rear mount turbo with a MS4 and PRC heads. Went to a front mount turbo with a Patrick G spec’ed cam and cleaned up 317’s.