can you use a rope rear main on a none knurled / smooth
crank?

Why would you want to, them old rascal are a real pain to install compared to the newer style ones I have a bag of them that will probably never get used now, unless I get to build another pre 1961 Mopar V8 like a Plymouth poly 318, poly Dodge, Desoto or Chrysler Hemi motor that the newer rubber Viton type seals won't fit into or work in the main seal holder

not having any luck with rubber and getting sick of being dripped on

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

its a big block
if i put the rope in there any chance of do any damage to the crank?

Its not going to hurt a thing.......except your feelings when it leaks.........LOL!!!!

God knows i been there a few times in my life

Three things to look at before you start replacing the main seal again, is the oil leaking out of the side seals? If not, is it leaking from above the crankshaft draining down onto the crankshaft and getting slung out from there making it looks like the seal is leaking or is it in fact leaking out of the main seal itself, or maybe the oil pan gasket above the main seal
I've seen more than one main seal get replaced when it wasn't leaking to start with
Try squirting brake cleaner all around the rear of the seal holder and the back of the crankshaft flange that faces the block so it is really clean and put it up high enough to look at while the motor runs with the dust cover off the tranny or bell housing to help you see where the oil is actually leaking from
I've seen main seals replaced when the oil was leaking from the rocker arm covers on B,RB and 426 Hemi motors more than once

did you lube the lips of the seal?? if so what did you use? just curious.

Go ahead & install it. put some sealer under it & cut the ends 1/4 above flush them tamp em down. You will be fine

well we tried another 2 piece rubber seal idled for 30 min. high idle for 10 and another 10 min low idle
bone dry how long before i can quite holding my breath?

Now take a deep breath and share with us what you found to fix it
Never quit, NEVER

seal ends at 12 and 6 some 518 sealer on the seal ends small about of motor oil on the seal to lube it no side seals just some rtv black silicone put some up in the block incase
the rtv on the retainer got scraped a little on the way up all surfaces super clean and dry with brake clean and lots of reading on this super site 2 hours and 20 minutes
run time and still dry

Im going to a rope seal on all my big block stuff. I did all the necessary precautions on the 440 in the ramcharger and that thing leaks like crazy, so I talked with a few guys and they all said rope seal.

So with that and this thread Im doing it. I cant stand leaks let alone the messy floor, but the oil splashing all over a clean chassis pizzes me right off!

The factory made thousands of BB cars with both seals, very few leaked
The rope seals are harder to install properly so they don't leak and they need the knurling to help wipe the oil off the seal
If your crank is smooth or worn down on the knurling use the newer Viton rubber seals and use a adhesive type silicone sealer to seal the two ends together and to seal up the side seals to the seal holder

Cab, Ive literally done it all...

I have the tool to trim the seal, its not a big deal at all.

Ive even tried offsetting the seal, my next bet was a 1 piece seal that's cut that you roll into place, then I talked to a buddy up in South Dakota who literally puts hundred in a year and he went with the rope seal.