Stirling engine built from trash and clippies

[dizekat]

My first Stirling engine.
http://dmytry.blogspot.com/2009/06/stirling-engine.html
As I found out, regular hole (0.7mm) with regular paperclip displacer rod going through (not a tight hole. Paperclip slides freely) is airtight enough even though I got 2 of them, and it can be sealed 100% tight with drop of liquid (I think pressure over hole is smaller than meniscus pressure, so it cannot make a bubble) but that doesn't seem to make any noticeable difference. The displacer must not be too close fit, because too close fit displacer has a lot of air resistance.
It runs well on the drinkably hot water, without any ice on top. The trick seem to be in really thin shaft, and low friction on displacer rod.

edit: expanded explanation.