ORIGINAL: ace4-40
ABC engines are not lapped with anything. If there was lapping compound in it, someone put it in or someone a the factory screwed up.
Even back in the day of lapped engines using lustrox was a bad Idea. It was poured into the intake while the engine was running. This not only lapped the piston/cylinder, it lapped the crankpin/conrod fit and crankshaft/crankcase fit and that was the front end seal. Bad idea making it bigger/looser rod big end a sloppy fit.
Lapped engines needed a slow long break in. Trying to speed up the process usually ruined them.
ace4-40, i am model engine builder and know what i am talking about this lapping procces both in older "iron" engines and ABC engines.....
See the pic of the piston and sleeve are lapped in post #25 and #16:
http://www.rcuniverse.com/forum/fb.asp?m=6286262 ,
http://www.rcuniverse.com/forum/fb.asp?m=6267829 .
Read in post #22 how the piston and sleeve are worked, lapped to fit togheter, translated from russian:
http://www.rcuniverse.com/forum/fb.asp?m=6281801
All parts who are lapped must be cleaned with ultrasonic bath to remove all lapping pasta out of all pores in the material. In case homemachinist: all parts are washed in gasoline/kerosene to remove all lapping pasta before use.