Gentlemen, Thanks for the Info.I wound up sistering the New joist with the old.Had to drill out hole for romex going through it,just measure it and drill.was close enough. Disconnected the romex and re pulled after the joist was in place.Purchased a new 2x8x12 from depot. Had to go through the whole pile to find 1 that was good.i jacked the old joist up ever so slighttly until it fit with a little hammering. Hammered into place and then used nails. Ill have to check the specs on the nails. I didn't use liquid nails, didn't see the post in time. will double up on the nails then. My first instinct was to rip the old joist out and replace, but after considering it nailed from up top,this was the easier way to go.Thanks everyone for the posts and help.
Should be OK without the adhesive if it's nailed well. The standard 'rule of thumb' is one nail for every nominal 2 inches, so a 2X8 will need four nails across, and I'd run that pattern every foot or so. You should be using 16d Coated, ring shank, or spiral nails. Commons don't hold as well, but they've worked for a hundred years when there was nothing else so I wouldn't worry. From the sound of it I'd say
Job Well Done!
Sistering the joists together is the best idea. And remember both the joists should be of same size and attached them with each other tightly. That will make them able to bear the weight of hardwood floor and other things.