I just put a new cam in my Falcon six to get rid of the 280 duration stick that was in it (automatic also). I bought a Comp Cams 252 and new lifters. One of the new lifters would not slide all the way down the bore, it kind of got stuck, so I used a magnet and a pick and got it back. On closer inspection, there is a crack in top edge and has allowed the upper part of the lifter to expand just enough to not slip in, which is good, because otherwise I would have unknowingly installed a bad new lifter. Since I bought these parts mail order, I was kind of frustrated, so I put one of the old lifters in. I know this is not recommended, but they have less than 5k miles on them, and I put a straightedge on the base and it was still flat. I haven't put the engine back in the car, but I did put the head back on. Now that I'm back in the house, I'm having second thoughts, and if I get enough "You idiot, you should pull the head back off" responses, then I'll do it, but sort of just hoping for a few "I've done that, don't lose any sleep over it" responses.
Put a new one in. If nothing else for peace of mind. If you don't, it will probably bite you on the ass and you could lose the cam to boot! Usually you always use new lifters, as they get a wear pattern to the individual lobe.
Thats a no-no ..... Once a cam is broken in the lifers are mated You can put new lifters on a used cam..... But NEVER a used lifer on a new cam Unless You want to change it again next week Tony
You mite as well use all used litters . Will you be happy with the car if 5 cylinders run good? Change it