heres something i want you to do... if you are running stock stud mount rockers... take the valve covers off and run a straightedge across your vavle studs.... this is a common problem with some of the stock rocker setups if you add even just a mild cam.... if one or two studs seems a little higher.... then whats happening, is your rockers are trying to go further than they are slotted for, they will pull the studs out of the heads.... i've seen it happen on about 20 or so engines now..... have the studs replaced by a skilled machinist.... and put on roller rockers....