How much to mill off a head?

[edgewood bronco]

I've got my head ready to go to the machine shop, if only I knew how much to mill.
the chambers came out at 59.2 to 59.8 cc, and it looks like I want to get to 52 cc to achieve a 9:1 compression ratio. That assumes a 0.050 head gasket thickness and 7 cc dishes in the pistons, which I'll verify when I get home tonight.
If that assumption is correct, then how does a reduction of 8 cc translate to thousandths of an inch milled from said head? It's a D8BE head casting number. I can see the impression of the head gasket part no. D7BE printed backwards on the head, so I assume that this head hadn't been worked on prior to my getting ahold of it.

My goal here is to be able to use regular gas in this thing. If I'm pushing my luck at 9:1, please let me know!
Thanks!

 

[JackFish]

I would think the machine shop could mill it to meet your specification of a 52cc chamber without you having to do the math for them.

 

[CNC-Dude]

Are you doing a valve job, this can change the amount they remove? Once they get the head setup and leveled in the surfacing machine, they will fill the chamber to your desired cc amount and measure down with an indicator to see how far below the surface it is. This will give them a very close starting point and target to mill off.

 

[edgewood bronco]

Wow. I didn't realize that they should be able to do that. I'm doing a valve job, so that'll have to figure in as well. I'll check with him tomorrow.
Thanks!

 

[rbohm]

when you talk to your machinist, tell them what combustion cc you want at the end of everything, as well as any other work you plan on having done.