I went to type 67 but my fingers typed 61, after doing a lot of searching is seems that I came up with a lot more info on the .61 so I typed that by mistake, The search function turns up different information depending how you spell or miss spell words also. I found some threads where Dave Trible and a few others were talking about the .67, and one had a picture. I'm pretty sure it's a .67 then, the long stroke engine, with the bars stock case and black head. Just from looking at it in person, I can believe its a long stroke engine, looks almost awkward. The .67 seems to have been around a while and is a favorite to a lot of people. Came as a SE version also. it appears to be a dual purpose engine for muffler or pipe, and a lot of people have used it to replace ST.60s as it's a drop in replacement. My friend has the pipe charts that are here on the section, but any practical use information would be helpful. he's just breaking the engine in now and drawing up the model for a winter build. Knowing what a practical range for the pipe length would be would be helpful. He's primarily run PAs to this point and given the nature of this engine, I don't know if he has any idea of what mode he might run it in. From what I have read in searches, and looking at the charts, allowing for a longish pipe length between 20 to 22 inches might be necessary, given the nature of the stroke of the engine. Getting some good feedback from others ought to help him male a decision on a set up that wil influence the fuselage length.
Type at you later,
Dan McEntee