How much will have to be milled off a dart 308 head to reduce the volume by 5 or 6cc's? Is there a chart?

Unshrouding the valves and clean up will add a couple cc's to so may be up to 8 or so.
Thanks.

I would cc them then refill with the volume I was looking for and measure the gap between the water and the head surface. Not exact but will get you a good idea. Just a thought.

that will work just need a depth mic and level the head and check the depth in a couple of spots

Ok, liquid tends to "grab" at the edge and anything you stick near it, but that will work for an initial stab at it. Will make a final cut when it's close.

creating the meniscus
always measure from the bottom, low spot

.006 per cc for flat mill

So .035ish then? Good ballpark.

Use a surfactant, soap?

If you take off more than .030, you will most likely need to have the intake milled to fit also.

^^And might need thicker intake gaskets^^