"Bob Engelhardt" wrote in message
...
First, some nomenclatu plumbing pipe is named by its nominal ID. Your
5/8 OD copper pipe is what's called 1/2". And it's highly standardized -
how a piece that's .655 got into play is the question. Unless it's 3/8"
threaded brass pipe, but that's larger, about .67 OD.

The 3/8" brass makes more sense, 'cause it was often used to plumb
toilets. I don't think that I've ever seen a toilet plumbed with 1/2'
pipe. Is the pipe-valve connection threaded?

The solution is to replace that .655 pipe between the valve & the toilet.
If the toilet valve that it connects to requires that size pipe, replace
the valve too. That's highly unlikely, though, unless the valve is
Victorian era. And then it should be replaced anyhow.

Bob

It's soft copper tubing, easy to bend by hand. This is an older house, not
sure why the tubing is too thick though. Flare fittings might not be as
critical OD as compression fittings are, might work fine for flaring.

RogerN