distributor issues

[bigthings12]

ok i have a 99 f150 completly modified it has a 351w carberated motor with a five speed tranny 4x4 it has 11" of lift an 3/4 ton rearends this is my baby i just got the truck so im learning a lot about it i have been having issues with it starting. it dose great when the motor is cool but as soon as i drive it anywhere an shut it down it is really hard to get it to fire off turns over fine but just wont fire. i checked today an found the distributor is loose i belive that this is my problem like i said im new to this stuff so im learning. how do i know the right setting an placement for the distributor so i can fix the starting issues. i can just twist it back an fourth an belive that is not right any help thanks