What should you do if you have tiled tub surround and the faucet pipe is too short and you can put the faucet back on but it will just turn a couple of times and is not tight enough to prevent leaking?

Examine the pipe, you can probably turn it out using a pipe wrench, and replace the pipe with one that is 1/2 inch longer. Alternatively, if you can get a couple turns on the pipe, just wrap some Teflon tape around the pipe and see if that stops the leak.

AnswerI would change out nipple to longer one, and then get a new Delta spout with brass adap. When you install spout it will go back to tile all the way. I think if you added .5in. nipple it would make it to long, then it would not go to tile wall all the way. Or do the teflon tape around pipe and see what happens.

ANS 3 - The piece of pipe sticking out of the wall is a 'nipple', unscrew it with a pipe wrench, measure it and get on 1/2 inch longer, put pipe compound or thread tape on the end and screw it into the fitting . Now re-fit your faucet.