sm blk X and J heads
i have a burrette and have cc'd a pair of 915's with 2.02 intakes ...72cc
About a 1 cc'ish diff between those and the 1.88 version. The factory 2.02 tulip valve gives up volume in the chamber, meanwhile takes up volume in the port, more than the chamber. The same casting 915 intake port volume -155 cc w/2.02 & 160 cc w/1.88 is what I have found. Good heads for factory stuff, my current set I modified and run flow 250cfm by .400 and go over 280cfm @.500
FWIW If you want actual chamber cc, just to know what it is without crevis volume of plug "which is different from running chamber cc aka w/plug crevis volume figured in" take a spark plug and remove the strap, insulator, and fill it flush with some wax. That's is not how you figure final compression ratio of course any idiot would know this...its just independent logging of all volumes/crevis volumes. As for as cast chamber size... 67 cc was the smallest j head chamber I've ever come across, one out of 4 that were 69cc..then I have a set of stock J 2.02 that are 72cc
The casting specs online are all over the place, 273& 318 heads vary quite a bit, stock 302's at 64.4 , 273 315 @66-67c , 675 @68cc