small block heads

Back to the original question. Set you heads chamber up on a level horizontal surface. Spray some WD40 in the chamber and use a medical syringe they have clear graduations mark on the side. Your no building a pro stock engine so will be near enough.My J heads that have been messed with over the years are 60 cc's.
I used a thin layer of grease on the mateing surface of the head to hold the plexiglas to the head. What's the wd40 for?