Another puzzler from my own collection. This nicely-made plain bearing radially-ported diesel arrived years ago in a multi-engine trade. It bears no marks of identification whatsoever. When I first saw it, I thought that it might be a Pfeffer from Czechoslovakia (now the Czech Republic) - it has a definite Eastern European air about it. However, inquiries amoung Czech experts and reference to books on Czech engines confirmed that whatever it was, it was definitely not a Pfeffer. Indeed, it didn't seem to be of Czech origin at all.
My next best guess would have been that it's a Jaskolka from Poland, but I could find no evidence that they ever made a 1.5 cc companion to their well-known 2.5 cc models. The only other possibility that I could come up with is that it was an AERO 1.5 made in the former Yugoslavia. I don't have an image of the AERO 1.5, but I do have documentary evidence for its existence.
The engine has bore and stroke measurements of 12.3 mm and 12.5 mm respectively, for a displacement of 1.49 cc. The shaft runs in a plain bearing, although the bulge at the rear of the main bearing housing implies that a single rear ball-race version may have been contemplated.
As received, the engine had no needle valve, so I added a Webra assembly, which was a perfect match; don't be fooled by that component! I also added the bronze spacer behind the prop driver to limit the crankshaft end-float, thus preventing the rear of the crankpin from contacting the backplate. Otherwise, it's complete, original and in very nice condition. The quality of construction is well up to the best commercial standards for diesels from the "classic" era. The engine starts and runs very well, albeit not with any remarkable power. Definitely a sports engine!
IDENTIFICATION MADE! Before this engine had been up on this page a week, my valued Hungarian friend and colleague Ferenc "Somi" Somogyi had consulted with his friend Peter Valicek, who drew attention to the home page of the fine website maintained by Region 16 of the Model Engine Collectors Association (MECA). There's a very useful link called "Motoren" which allows you to scroll through a gallery of rare and unusual engines. And there it was - see the attached colour image extracted from the MECA web-site! It's a Jaskolka 1.5 cc diesel made in Poland in around 1955. The one illustrated on the MECA website has a red-anodized cooling jacket, spinner and prop driver, but otherwise it's identical - indisputably the same engine.
Many thanks to Somi and Peter for solving this one! Before this identification was made, I wasn't even aware that there was such an engine as a Jaskolka 1.5 cc diesel!