High closet flange

I know this has been discussed previously and I`ve read many,if not all of the suggestions.Some were useful and some just impractical.So I`m looking for some input.Here`s what I have.I have a 3.5 cast iron drain with a concrete floor.Where the concrete contacts the pipe on the back edge it is almost 1/2" higher than the front edge.The closet flange is relatively level though.So when the new toilet,an American Standard Champion 4,sits atop needless to say the rocking begins.When I took the horn(funnel) out of the drain it fit much tighter overall but still had some rocking.I have not yet put any wax down.....all of this has been done as a dry fitting so far.

In the tail of the bottom of the toilet are 2 molded slats that act as support I imagine.It just so happens that they coincidently reside right on top of where the mounded concrete is.The question is whether of not I could either 1)grind down these molded slats to a degree that the toilet would nestle down snug over the closet flange with the result being a 1/8 gap...easily caulked?
2)Trace an outline of base onto existing newly installed vinyl flooring and try to chip away the concrete.
3)How necessary is this plastic funnel really.I`ve read various descriptions about where/how/why to install it. It appears to me that without it I increase my space where the bottom molded flange of the toliet encounters the opening of closet flange.Wouldn`t this space,useful to get a level effect,eventually become watertight by the wax ring without the flange.It just seems to get in the way here.I`m having a difficult time trying to figure out if the concrete floor,where it`s kinda mounded in the back section is more of the problem because of those molded pieces on the underside of the toilet base OR if the cast iron/closet flange duo is the real culprit.

Other considerations are this problem exists in a below grade portion of the house.This cast iron pipe is 50+ years old.To gain access to the stack and change this out isn`t an option.

I understand I can also trace and make for a plastic/plywood mold to achieve a level playing field but I think it will look,,,,,pardon the pun,,,,,crappy.

So,any thoughts new or old would be welcome as I watch my Eagles and do some woodwork.Thanks in advance.

The drain pipe is measured ID, so it is a 3" drain pipe. Your best option is to remove the existing flange and install a new one so that it fits flat on the floor. this may require chipping some concrete, but not a major tearout. A plumber is best, since leading a connection is not something most people have either the tools or skill to perform.

I would be very leary about grinding the toilet. Avoid wax rings with plastic horns in them...they cause more problems than they solve.

Question Jim???

Are you saying that the new flange will have to be leaded on? I assume that means the old one is leaded in place. I tried to remove the existing flange but thought it was just rusted on so I stopped because I didn`t want to create a bigger issue. I thought maybe it had some hidden set screws somewhere that I couldn`t find.

Thanks.

Yes, the old flange is likely leaded in place. First you use some oiled hemp (oakum) that actually creates the seal, pounded in, then after that's in place, liquid lead is poured into the remainder to hold things in place.

If you look carefully, you should notice a ring of lead between the CI pipe and the CI ring (flange).

There are some alternatives, but not really for a pipe embedded in concrete...those that clamp on the outside of the pipe need room to access the tightening mechanism. On a 3" pipe, you don't want to restrict the opening by using one that fits inside the pipe (you could if it was a 4" ID pipe). So, that leaves you with leading on a new one.

As mentioned earlier, if it isn't too low, I'd consider just leaving it there and either using a thick wax ring (or two stacked), or a waxless seal - Fluidmaster and Fernco both make them. The best solution is to replace it with a new one at the proper height.

Thanks for the help.....

Went with a thicker wax ring sans the horn.So far so good...no water anywhere,powerful flush.It`s a little higher still in the back but very sturdy. It`s kinda funny since I work as a construction inspector on the commercial side that I never really took more than a casual notice of CI installations.I knew what the process was with the oakum and lead but just never made the connection to residential use. Always good to learn something.Thanks again....