undersize rear main seal

does anyone make undersize rear main seals for cranks ground undersize on the rear seal journal?
if so, then rusted/pitted cranks could be saved.

Me thanks you mean oversize rear mail seals so you could grind the seal area down to smooth it up, correct?
If so, due you know about the original rope rear main seals that Ma Mopar used forever before switching to the new style neoprene and Viton formed two piece rear main seals?
They, the rope type, should work well on a rusted and pitted main seal area as long as the rust is remove and polished down some to make a smooth sealing area for the old style rope seals to seal against

there are no under or over size inside diameter rubber seals for any of our SB or BB engines.

As Cab suggested, the early style rope seals would be your best bet. However, be aware that their installation is critical.. and.. the current material is very difficult to cut flush upon installation. The early original material was made with asbestos rope and graphite lubricated... easy to cut. The newer generation (for past 30-40 years) is now made with a Kevlar material and very difficult to cut... takes additional time.. and requires a very sharp serrated cutting blade... but the rope is dominantly replaced by rubber seals.

I'm a former gasket engineer and know the history of this matter.

NOTE: Certain late-model crankshafts can have a press-on metal sleeve installed, however, those designs of cranks cannot have a flange at the end. Similarly, many harmonic balancers have sleeve available to save the balancer and provide a new sealing surface.

If you go the rope seal route get a BEST GASKET rope seal , the ones that come in the fel pro kits are a pain to work with and keep from leaking .

Best Gasket rope seal

well,they call bearings undersize when the bearing journals are ground undersize was my thinking. anyhow.....hadnt thought about rope seals as i know they are a real pain.thats a good suggestion though because its a shame to scrap otherwise salvageable cranks. i appreciate your idea,and may try it if i can find a good enough rope seal that can be cut cleanly [as someone mentioned here]. thanks.

sounds good. where to find a "BEST GASKET" rope seal? thanks.

Doesn't a factory rope seal require the directional "knurl" on the crank to work properly?

If you machine that sealing area smooth won't it leak?

I was always taught rope seal--knurled, lip seal--smooth.

Both type seals will work on either type crankshaft

If using a neoprene seal, shimming the seal cavity in the block and retainer would probably work but the mating ends of the seal would need to be trimmed.

I provided one in my original reply.

Except you can't buy direct from Best.

Here's the link to the distributors page, pick your dealer

https://bestgasket.com/distributors/

Something may have changed since I bought some many years ago , I'm 99% sure I purchased directly from them ?

If you’re having the rear main seal area cut down…

Make sure to have the machinist put the knurl back on the surface. And make sure the knurls are going the right direction.

Many aftermarket stroker cranks don’t have the knurl and most seep oil. The stroker cranks that some builders ask to be cut for knurl are much better improvement. SCAT can cut knurl on their cranks for an added fee. They don’t like to and resist it. Just be persistent.

Troy here just built a Hemi with Barton rotating assembly. Guess what? Rear seal area was knurled. And it doesn’t seep oil. The Eagle crank in Troy’s other hemi built 10 years ago leaked immediately. Then a rope seal helped. But not as good as the knurled Barton crank.

Good info , I will have to ask around to see if someone can put knurling on my eagle crank here in the northeast.

I've built and raced a bunch of stroker motors with no knurling on the main seal surface with no leaks using the new type of Viton or neoprene rear crank seals
I had more troubles with rear main seal leaks on BB using the old rope seals
That knurling provides a small shallow path for oil to leaf out of
I've had that surface polished a lot by crank grinders when having stock cranks ground down on the rods and main journals to help seal the rear mains up
I also use a good brand of adhesive silicone to completely seal the side seals up on the rear main seal holder and the block