Std head unskimmed measures 139 mm.
My head is 138.6 mm and the combustion chamber measures 46 cc.
Std 4 wd Piston Dome Volume is 19 cc, and my new pistons have 24 cc Piston Dome Volume.
For the record.....it's a 2wd head.
as my head is 1mm less than std, i have guestimated a std head to be 51.25 cc
Can't say that for sure because the combustion chamber of the head isn't symmetric.
Why do you wanna know? You want to calculate the comp ratio?
Regards,
Bas