??? WTF.. Diameter is 0.408
your seat (marked as vent in your pic Smile ) seems quite large... have you measured its ID or OD ??
the .408 diam is the seat diam inside the piston. i marked it as vent diam on the pic i posted of the piston opened. sorry i should of made that clear.
do i need a measurement of the barrel that holds the piston/spring etc to get a not garbage pilot volume number correct ? if i have the correct idea there it comes in at about 1.299 wide (0.6495 radius)
0.6495 squared is 0.4218 times by pi is 1.325
this is looking more like the correct maths i think?
Just how did you get 16.64??
i honestly have no idea but hopefully with the maths above i am on the right track .. had to learn all this stuff from scratch sorry i never knew maths would be useful when i was in school haha. thanks for being so patient with me