Here's a pair of glow-plug engines which are clearly from the same maker. They were submitted by Tim Dannels. Looking at the style of their plugs, they have a bit of an Eastern European look about them.
Tim hasn't measured them up, but assesses them as around 1 cc or possible smaller. Both are barstock productions all the way. They are identical apart from the induction - one has a reed valve, while the other has a rear drum valve. Both feature radial porting.
Someone out there must surely recognize these two! If so, let's hear from you!