Originally Posted by
TomB
you should never lapp a piston and sleeve. when you do this, you remove the cross hatching on the sleeve,
and ruin the fit and finish, also the cross hatching asists in allowing to oil to have better surface tension and
do it's job. it it has no cross hatching, it will be too smooth and the fuel will not work/movearound/and stick
to the piston sleeve surfaces as intended.
I have seen people lap the piston leaving enough room for some break in. I've seen p/s sets that are so tight that it either ruined the rod or there was hardly any chrome left on top of the sleeve to create a good seal... You do need to measure before lapping and make sure you don't lap too far down the piston.