Big AL is right about % {valve-seat} and MOST of the dyno's on my web site were 87-88 % intake ,ex. were different. He is also right about sharp angles on the intake seat ,ex. different. If you want to know what these 'stock' 110" heads flow ,ask DON deweysheads, I am sure he will tell you. BIG HOLE - NO FLO !!!!! In my opion , these are good heads ,they just need a 'little' valve-seat work, and when you 'mill' {flycut} .050- .060 off of them,you make the combustion chamber smaller and pretty good. You can 'machine .040 off the heads with no problem. More than that ,make a alum. washer the put under the comp. release to raise it up. Dewey ps. got my 30 tooth front pulley today ,yahoo.