Re: 4" Cast Iron usage with 1.6 flush toliet
Before you purchase the new toilet, measure how far away from the back wall the bolts holding down the existing toilet are. The standard measurement nowadays is 12 inches; some of the old toilets were 15 inches or more. This means your new toilet could end up sitting 3 or so inches away from the wall. If the measurement is less than 12 inches, the new toilet won't fit at all.
You can get modern toilets for different measurements, but they are special-order items, and the selection may be limited.
The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.