For those who have subscribed to the defunct Strictly IC, you may remember one of their cover photos being a 7-cylinder radial which was created using Saito 4-stroke model engine heads. It was gorgeous! For a miniature radial, it was also a bit on the largish side.
Saito 4-stroke model engines, aesthetically, are the best, IMO. They have angled, separate rocker boxes, unlike the O.S. series which have a single rocker-box cover and perpendicular valves. For quite a while, I have been toying with the idea of creating a similar radial engine except on a smaller scale. Horizon hobbies sells and maintains spares for the Saito line. I was thinking of using either the .30 or .40-sized cylinders and heads. Saito produces these as one-piece. Here's a link to the .40:
http://www.horizonhobby.com/Shop/ByC...rodID=SAIE040A
Picture 9 of these in a classic radial! I'd convert it to spark, gasoline, using forced-oil lubrication. About the only change to the head I'd make would be to replace the rocker covers (chromed plastic, I believe) with CNC-machined aluminum.
One way to produce this engine would be to scale the Hodgson-9 crankcase down a bit. What do you guys think? It would take some $$ to buy the necessary jugs, but ultimately it would save probably a year of work, and it would still be quite original.
One other IC engine concept would be 2 or 4 of these cylinders (or O.S. cylinders) in a flat twin or 4-cylinder opposed aircraft engine. I like the concept of using an available head/cylinder combo for experimentation. Anyone who has produced 18 or 36 tiny, stainless-steel valves would probably agree with me that $13 for a pair of precision Saito valves is a bargain, not to mention the rocker arms and other tiny fiddly parts.