THEFED, if you have a 0.100" dome on the piston, it's gonna be one hell of a lot more than 3.5 cc's. Figuring a mean (average) diameter of 3.250", here's the formula:

.7854 x diameter x diameter x depth x 16.387

.7854 x 3.250 x 3.250 x 0.100 x 16.387 = 13.59 cc's

What am I missing here????