You said 7 and 8 . Did you turn it after you put one in before the other ? Normally you are turning it some after each piston installed . I hate to say, that if you needed to ask the question, if it was normal to be so tight, you probably should have someone experienced helping you ! There are so many possible errors could have been made. Is a bearing cap mixed up with the wrong rod, or cap on backwards ? Did you check the bearing clearance ? Also check the side clearance between the rod caps.I don't know your knowledge level . There are a tremendous amount of things that can go wrong in an assembly process ! Also machine shops can make errors that can cause a problem . I once had a big block that seized every time I tightened one of the connecting rods. Come to find out, they machined the rod bore crooked, and it was pushing the bearing out the side of the rod bore.