when i got my truck the timing was off in it a hair...it was close enough that i loosened the distrib and turned it alittle bit to straighten it out. but instead of 10 btdc its timed at 0...could this be where my valve chatter is comeing from. i get the chatter when the engine is under a light load or when shift it alittle early...kind of annoying and embarrasing sometimes

 

Sounds like that "chatter" was pre-ignition and yes, backing off the timing does help that. As far far as timing marks being off, that could be a number of things. One being balancer has slipped.