What is this screw on toilet ballcock?

I am not sure but I believe what looks like a screw going into the side at the top of the unit adjust the refill rate (really a guess) I suspect there is a screw on the top that will adjust the height (float valve) of the fill.

That said, I doubt if your problem is there. I suspect if you just hold the handle down a little longer when you need a little extra flush, it will take car of the problem.

The screw on top is for the float. That is not the problem. The screw I am referring to in the figure is on the top right side. Holding down the flush lever does not really help. All the water is emptying from the tank OK. The problem is there is not a lot of water in the bowl initially to get the flush process going. When the bowl has a lot of water, it flushes fine.

So you are saying the amount of water in the bowl between the flushs varies? Most designs have a plastic or metal tube that feeds a small amount of water into the bowl by way of the overflow pipe as the tank fills. This is how the bowl is refilled. If this is not done, then the bowl will often not be refilled to it's design depth.

Correct. But on my toilet the bowl gets filled throught a seperate tube which rather than going throught the overflow pipe, get fed directly into the bowl, until the float for the diverter valve stops it, diverting the water in the tank. The float is mounted on the diverter valve shaft with a screw, but the shaft is keyed, so I can't adjust it.

Neither of which have much to do with filling the bowl...

Couldn't tell you. But from the diagram I don't think it has anything to do with the problem.

The hose coming from the side of the fill valve should be directed into the overflow. The water coming from this hose fills the bowl while the main flow from the fill valve fills the tank until stopped by the float.

In other words, is water coming from the hose, and is it all going down the overflow tube? If so, the bowl should fill. If it doesn't, perhaps that plastic screw does adjust the flow thru that hose. Remember (or mark) the starting position and try turning it a turn or two and see.

sdb

And it is possible that a crack internally can be draining the level down.

In other words, is water coming from the hose, and is it all going down

the overflow tube?

As I said in my previous post, the tube gets fed directly into the bowl through the casting of the tank. It does not go into the overflow tube.

And it is possible that a crack internally can be draining the level down.

If it happened everytime, yes it is possible. But it only happens occasionally

replying to Mikepier, Ken Brose wrote: It controls the amount of water that goes into the bowl.

SEVENTEEN YEAR OLD post, ace. But no matter, Mikepier got tired of waiting on your reply so he ripped the toilet out and now just pees in his yard. I'm not going to mention where he takes a dump.

HomeMoanersHub strikes again!!!! Make that HomeMORONShub.

does that large head plastic screw on the side of the 1B1X fill valve send extra water into the rim jets if it is turned one way or another? Will extra water help flush a one-piece low boy toilet better?

I haven't had this problem but I've heard that water minerals can narrow the ports in the rim of a toilet and keep it from flushing as well.

There is a way to redisolve the mineral.