early 273 pistons.

I cc'd my heads too, 58cc's. Took a clear CD blank and vaselined it to the level chamber. Took a turkey baster full of distilled water and weighed it then filled chamber up to the hole making sure there were no air bubbles, filled it so there was the slightest miniscus and then weighed the baster again. 58g short, so thats 58cc's. No drips out the ports so I believe that is pretty freakin' close. Nail head valves would pick up some volume.