[MBZ] Piston protrusion limits

[Peter Merle]

After rebuilding my 300D  I measured piston protrusion at 0.8mm which is
just within spec of 0.9mm. I find it strange in that the block is just
0.1mm short of a new one which means I should actual have 0.3mm
available. What is the limiting factor - prechamber collision or valve
collision with pistons. Has anyone got figure for valve lift vs crank
position for the non-turbo  ?
Peter