Need Help-- New Closet Flange to Old Iron Pipe

[fireduck]

Hello, I am trying to install a toilet in an older house that we have re-modeled. We are trying to get everything finished up to move in before Christmas, but I am having trouble finding a closet flange to fit the existing cast iron drain pipe. We have ran all new plumbing throughout the house, but the only thing I didn't replace is the toilet drain pipe. It is ~3.5" and the closets I've bought at Lowes do not fit. I don't know what to do, and I don't really want to change out the iron pipe, because all my other drains are already hooked up to it. (It was too intimidating for me to mess with, and it runs straight down from the toilet into basement floor and elbows straight out to a septic tank. Do they make a closet flange to fit this pipe? It had one in it before we took out the toilet, but I didn't think it would be a problem to get another, so I threw it out. Any help would be greatly appreciated. Thanks!

[fireduck]

Also, I was wondering about using thread tape on cpvc? I had tape and was going to use it, but I was told by someone that it is only to lubricate the threads, and that it is not recommended for plastic threads. (Ex. the male cpvc threads that all the sink supply lines attach to, and toilet, shower, water heater, etc.)

[phishfood]

On the first question, there is a flange made that fits inside of the cast iron pipe. Some plumbers don't really like them. I have not had any problems from them, but then again I have only a little bit of experience using them. My internet connection is excruciatingly slow, or I would do a search to post up a link for one.

On the second, I use thread tape and thread paste on all thread sealed connections. Be careful to leave the last thread untaped, as the tape in the last thread can make it hard to get the threads started correctly.

[fireduck]

Thanks for the info. I am going to a plumbing supply place today, they saidthey had exactly what I needed for the toilet. Also, I will go back and tape all my threads, before I turn water on. Thanks again for your help.

[fireduck]

Do you think I am crazy for not changing out the old cast iron pipe. I figured with it being straight then there is little chance for it to leak/fail. I guess in the future I could always go back and change it out, it is the only thing I didn't replace.