How far to mill 12v intake plenum down

[m880cummins]

Hi guys,

Have a quick question to run by you. I have my head at the machine shop scheduled to have a 3 angle valve job, mill .040" off HG, O ring and mill plenum surface for runner intake next week. How far do you mill it down? I have seen some where the surface has no rough cast between intake ports but I question how thick surface is for the valve cover gasket. Any pictures or experience?

Thanks

Charlie

 

[YoungDiesel27]

Zz fabrication says to mill it to 0.625-0.650" from the edge of the headbolt hole. I did my hamilton at 0.635" and barely have room for the valve cover to seal. It was mainly smooth but was a little cast between the runners but it was going to take another 0.015" to clean it up so I left it. Also when I bolted my intake on, I got it square with the lip of the head so the valve cover can seal on it too.