Thanks everyone, I need some new studs then, as they should be cycle thread above the case. For the record I reckon the stud should be at least 15/16 above the case and at least 1/2 in the case (I could go up to 5/8 with my cases), so the studs I have off a thin flange engine are just a 1/16 too short at best - just another item on the huge parts order I will have to place on some lucky vendor .......