I removed the fuel tank on my 450i to check the valve lash. No petcock nonsense to deal with, so it was easy. Pop off the hi-pressure fuel hose on the top and the tank is freed up.

The 2 valve lash adjustment ports are quite accessible. The intake spec was a bit over 4 thousandths, and I measured .003, so I opened it up a bit.

 

MXU, loaded for bear (wood).