Originally Posted by young grease monkey
am i misreading? it is NOT a good idea to try to get a flat surface, which is what lapping does, on something that is NOT flat to machining standards! if you want to use an orbital sander, stick the glass on it and then the sandpaper to the glass. i almost slapped myself when you said you lapped on a floor! look for a thick piece of glass that doesn't distort your reflection by a noticable amount, i think plate glass is the stuff. thick because you don't want it to bend.
it's not the first time i've lapped either the head or the cylinder. just the first time i've done it with an orbital sander.
i've done it several times on just my drive way with a sheet of sandpaper, and havn't had any head gasket issues.
the only one time i had an issue was because i had a bolt that wasn't torqued the same.
i even checked it with carb cleaner after i had run the motor and warmed it up, no leaks at all in the gasket.