Hi Gary, In my opinion, the 1700 RPM recommended in the 1980 (latest?) version of the Continental Operators Manual will provide a reliable magneto check for RPM drop with minimum foreign object damage to a prop over its service life. Alon and the M10 use that RPM for their C-90s. Forney recommends 1500 RPM for their C-90, presumably with the Marvel-Schleber carb.
Others may "choose" according to how they were instructed, or according to ERCO's manuals from the forties. With all the figures, both old and new from all sources, there is no one RPM that is more logical for C-85 "run up" than the 1700 RPM in the Continental Operators Manual. I remain unaware of any tangible benefit from mag drop testing above 1700 RPM, and believe if Ercoupers wish to minimize prop nicks and dings between annual inspections they "should" use that RPM for run up. It remains a personal choice, however. WRB -- On Nov 19, 2009, at 21:59, G. Jones wrote: > > > I am now confused;I have the c-85 HP, and a stromberg carb.What RPM > should I use to do my run up. Just to say, my engine runs very > smoothly at most all RPMs. > Gary
