3" ABS to 4" Cast Bell Hub

I'm remodeling our basement and have an existing 4" cleanout at the very edge of my basement wall. The fitting actually extends under the wall. The easiest place to connect my new system would be the hub of this cleanout fitting.

I think I've used these before, but don't they make a rubber fitting/bushing that fits into the bell hub and accepts the ABS? If they do, does anyone know if these would come in a reducer configuration (3" to 4" hub)? Also, since the line is horizontal and will be buried, would there be a concern regarding longevity or seal deterioration?

Thanks.

I think I found it!

I believe Fernco makes what they call a "doughnut". Slip it on the end of the new pipe, clean the inside of the hub, lube the doughnut with soap and plug 'n go.

co

I am curious about the cleanout fitting. It would be unusual for one to just be by itself going under the wall. Is this a Y-1/8 bend combination fitting and you are going to remove the cleanout riser and use that opening for your connection? If so it is a bad idea unless you keep the cleanout riser and make your connection to the side of it.

Cleanout

It's either a Wye with an 1/8 or a TY. Can't tell until I remove some more concrete. I'm keeping it as a cleanout and just changing all of the upstream plumbing to ABS. I've attached a picture.

The next question - Any suggestions as to how I can free up the threaded brass plug on the top of this old fitting (circa 1950 and has never been touched)?

Thanks

plug

A hammer and a chisel. First try rotating the plug by hitting its perimeter with the chisel, and if that does not work then cut it out and install a new one.

Hammer and chisel

Thanks hj

I kinda figured I'd have to take a hammer to it. Notice the hole just to the right of the bolt head. Will try to persuade it a little more by going farther out on the edge of the plug. Just don't want to mess up the female threads.