I had 30 thou shaved off my 4k head to raise compression. So i put it all back together today but now there is a really loud tapping that sounds like its coming from the top end its, not valve clearance or the rocker gear because i adjusted the clearances until they almost had no gap at all but it wouldn't go away so i put another rocker gear in and still the same I'm thinking maybe because of the head sitting lower the push rods are on a different angle that makes them noisy but I'm not sure what do you think?

Could it be pinging?

 

Have you rebuilt your engine lately and put the pistons back to front or anything?

bad fuel maybe?

Had a similar thing that could be described as "very loud tapping" in my 4ac powered sprinter.

 

Turns out it was a bent valve sticking and just touching the top of the piston. I drove it about 4 kms, and when the head came off, there were nice little knicks in the carbon on top of the slug!

 

Not enough to bust a hole, but it needed a head rebuild after that.

don't drive it no more and strip it befor it hurts itself...