Small Block Cylinder Heads 'Stock Specs'

The factory 2.02 j heads I have tested flow 228cfm intake and 142-147cfm exh.
The factory 2.02 j heads also have an exact 72 cc chamber.
The port volume increases from 160 to 165 with a 1.88 int valve due to the back side of the valve head having less tulip to it.
The 1.88 int valve j head flows 215cfm .450-.500

The 318 heads can be 124-125cc int port volume, the open chamber version is 68 cc while the closed is only a few cc smaller amazingly enough at 65-66cc.

The specs I give come from stock/as cast heads from 64-71.