if i'm not mistaken, some blocks need a slight grinding of the casting where the starter bolts up to prevent breaking[cracking] the nose piece as shown. the only one i have ran into that problem with is the mockup block i am using on my humpback project. after discovering that issue, since it is for mockup purposes and the block is junk anyway, i just have the starter attached with one bolt. if i were going to use that block, the grinder would come out to clearance the block as needed.