as far as I can tell without taking it off just the outside of the dogear where the bolt goes through (back right hand corner) cracked off. It didn't crack into any of the runners or anything, I just can't get any tightening pressure in that corner for the upper intake now. I'll give a go at loosening the rockers a bit. I don't hear the popping noise when it isn't fired up, only when it's running. When it's just turning over (don't have spark hooked up/whatever) I don't hear the popping.
I paid $~200 ea for the heads.
