>Or, maybe, the price (to repitch) might have risen to what Bill said. My $200 was to repitch. Bill's $400 was for an overhaul and repitch.
* Is it bad to run the C-85 engine at more than 2400 rpm in cruise when you have a flat, climb prop? No. first off, the engine is approved for CONTINUOUS operation at 2575 RPM at maximum throttle, i.e. 85 hp. BO times take this into consideration, so, basically, any power setting up to full power is expected to reach TBO. What determines power output is RPM combined with manifold pressure. Flattening the prop results in lower manifold pressure and hence lower power at a given RPM. * If the plane cruises at 108 mph with the 7150 prop, is it OK to turn high rpm to cruise the same airspeed? Yes, up to red line. Beyond that you are busting the regs. * Would that cause lower or higher stress on the engine than flying 108 mph with the 7140 prop? Good question. I don't know if you could make 108 RPM with a 7140 and stay under redline. On the other hand, you might not make 108 mph with a 7160 either, but your manifold pressure would be a lot higher... Bottom line, at 2575 RPM with a 7140 your manifold pressure and hence power output would be pretty low unless you were hanging the plane on the prop. Regardless, a normally aspirated engine running at or below red line will not make more than rated power. Regarding higher RPM's bear this in mind: The same rotating parts as the O200 (essentially) are used in the GO-300 which is redlined at 3200 RPM (continuous)... John Cooper, A&P Skyport Services PO Box 249 4996 Delaware Tnpk Rensselaerville, NY 12147 518 797-3064 Fax 518 797-3865 www.skyportservices.net
