Korky Toilet fill valve

I am installing a new Korky toliet fill valve. I have followed directions good I think. When it's flushed the water level shuts off nice. but then you hear small noise a little gurgle & look back in & water has made to way to top of overflow valve. I have it set down & turned to left in locked position. ??

I would double check your 'locked posistion'.

During the repair, you may have dislodged some crud and it is caught in the sealing gasket. Take the cap off and check. The instructions came with it and are at their site. Should take all of a minute or so once you figure it out.