Cam Timing Methanol Glow Engines

[petertha]

For any of you RC engine enthusiasts, I found this website which has a nice selection of past engine reviews. You know, back when 'review' actually meant disassembly, measurements, run testing, useful commentary, performance numbers... as opposed to the more modern pain of watching someone open box & slowly unwrapping an object... but I digress.
Sceptre Flight

I was there principally looking at carb sizes (more on that later). But while I was harvesting numbers, I also made note of the timing where it was stated. I was curious about the range & mostly how my radial compared to them & other multi-cylinder engines in one picture. I just extracted O.S. 4-strokes across the displacement range so it may have their design bias. I could probably go back & harvest some Saito or others brands too. If you have any data or links, I'm happy to add it on. Note these are all methanol glow 4S so please don't infer its directly applicable to gasoline or other types of engines.

Here are some screen grabs of my spreadsheet. Even among the O.S. engines its a bit of apples & oranges of course. The designs span over many years, these commercial single cylinders are happy to run at relatively high rpm, the valves started to grow over time, usually had muffler pressurized fuel tanks feeding carb & other variables in the mix. Hope the chart makes sense - the dots on the comparison graph correlate to the more familiar timing diagram INT/EXH duration bars. It was the only way I could think of displaying it.

 

[cwelkie]

Thanks Peter for sharing your research. It is interesting to see the (apparent) relationship between displacement and valve event timing/duration for the OS engines.