timing off or bad valve spring ?

[Mr 5 0]

Originally posted by gtstang83

...if the timing is off, would that be enough to cause a tapping on only 1 side of the motor, or an i looking at possibly valve spring replacement time?

It isn't very likely to be your timing that causes the tapping (although you should check it).
It could very well be a tired valve spring or a 'bad' lifter or just the usual 5.0 lifter noise that many have. I've had a slightly noticable lifter tap on one side from the day I drove my Mustang off the lot - 12 years and 115,000 miles ago. No big deal.

Check it out, pull the valve covers and do a visual inspection at least but you may just have a gummed up lifter. That can sometimes be cleaned up with solvent and some very frequent oil changes.

Good luck.