What is the best way to remove a threaded stuck lead fitting from a cast iron section? The fitting was from a lead sink drain pipe and it connected to the cast pipe at the toilet elbow. I tried a pipe wrench and a hammer to try to budge it but no go. I want to thread new PVC into the section of cast for new drain lines. Can I use mapp gas to heat the fitting?

" Can I use mapp gas to heat the fitting?"

If you're sure the male threaded fitting's lead and not a brass Midland Bushing then you may melt it out with a torch. However, that's messy and will leave melted lead in the threads that can be difficult to remove. A much easier way would be to saw the fitting down to the threads and simply peel it out.
Good luck, Tom

Speedball,
At first I thought it was galvanized, then I started knawing at it w/ pliers and it turns out to be a big lead fitting. Would heat at least soften it up to be able to turn it out or is it just better to just keep peeling it apart w pliers?

About the time it begins to get soft it's right on the verge of melting and if you soften it down enough to turn it you'll just tear it up with a wrench or a pair of pliers. The safest way is to peel it out of there. Tom

Thanks Tom, that's what I'll do. Mike