Peter, So far I found no adverse running effects of the equally-spaced link rod pins in the master rod. The drawing of the cylinder liner ( the Robert Sigler version) specifies trimming of the liner top to achieve equal CR for all cylinders. I myself adjusted the CR by trimming the piston crowns to the correct height because in case of an error is is easier for me to make a new piston than to go through the elaborate and messy process of making a new liner. As far as the spark ignition of the original Edwards is concerned: I found proof on the website of the Miniature Engineering Museum Collection that the original Edwards did have spark ignition. I wonder whether Forest made corrections on the position of the link rod pins or that he kept the equally spacing. Either way, it seems worthwile to investigate how the linkrod configuration was arranged in "real " radial engines.