Please help!!!
 

Ok so i had a leaking tappet cover and while I had my truck extremely dismantled I also added 4k gov springs 60 lb valve springs and put it at 16* timing.
I went to go take a test drive....got it bled and idled fine....left the house and got down the road and started making like a thud thud thud sounding like it was coming from the exhaust. Not a clang cling like it was valve interference (scared the crap outta me) so I limped it home and it kept getting louder and worse.
So since the problem developed with rpms.....although I never exceeded 2000 I think my timing has slipped.....but I checked it and it was .218" plunger lift which is 16*.....so I have no clue.....it couldn't have slipped back right?!? I really need to get my truck running!!
Thanks for your time
Justin