Is it a small or big block? Don't think the rope would work well on a slick finish journal. If it has been line bored a lot, that may be your problem. On chevy's they make special main seals for line bored blocks. On mopars I don't know of any. But what I do is take some brass shim stock and silicon and insert a shim on the seal where it slips on the block and cap, this presses the seal a little tighter and will compensate for the material removed during line boring.
If the block is line bored, the seal is already tighter on the crank on the block side, because you machine some out of the saddles but you don't machine the seal groove. So seal is same, saddles are lower
