A question came up on the other forum, so pasting reply as further elaboration if my saga verbiage was not quite clear.
I don't think there is an advantage to excessive interference, in fact several potential disadvantages. For example, in my case where the cylinder shape is tapered & thicker wall near the top can contribute to different shrink force on upper vs. lower liner. Pretty much every RC engine I have disassembled requires oven heat to install & remove the liner, even when brand new. My initial heat testing was based on a separate spare test cylinder which was the original design, not my subsequent modified design. But I think either reamed ID surfaces were not as consistent, or possibly they stress relieved a bit. In this kind of application, a half thou one way or another seems to make a big difference. My longwinded story was just to say in hindsight I would not bother grinding & lapping the liner bore until mated to cylinder & completely stabilized. Unless you have good shop methods to very tightly control both OD & ID dimensions & finishes. Jung provides these instructions in his 5-cylinder engine which is probably not far off how mine ended up after lapping the cylinder ID (0.02mm = 0.0008”).
To ensure optimum heat transfer, the cylinder liners must be shrunk into the cylinders. The inner diameter of the cylinder is about 0.02 mm smaller than the respective outer diameter of the liners to unscrew. After uniform heating of the aluminum cylinder by means of gas burner or hot plate (to about 200 ° C), the cold liners are inserted into the cylinder.
