What I did for the piston measurement was.
Put the piston in until the dome was level with the deck. Measured the distance from flat portion of the head to deck. (.349)
I used the 4.28 bore and .349 to get a theoretical flat top volume. With the piston in the same place I CCed it. I subtracted the cc fill from the theoretical volume. After your question it guess I should have added the .021 to the .349.
I hadn't seen the screenshot of the calculator prior to my previous post.
It looks like it's correct there.
I ran the numbers before looking at the data on the screenshot and got 9.75.
Were you/are you really going to use that big of a gasket?
