Alan,
I agree with the theory that there is an engine power output problem or that the prop may be the wrong one for the engine. Could also be a bad tach, but the lack of performance tends to indicate otherwise. Here is a link to a cheap RPM checker: http://www.aircraftspruce.com/catalog/inpages/onetouch.php Try checking the easiest things first. The first check should be to see if the throttle is opening completely at full throttle. With the mags off, firewall the throttle and see if the carb is hitting the full open stop, also make sure someone has not adjusted the full open stop screw thinking it was the idle screw (saw this problem before) Disconnect the throttle cable and see if there is any additional opening travel. Remove the air filter and be sure the carb heat is full open. Use an inspection mirror to insure that at full open throttle the butterfly is absolutely inline with the airflow, it could be adjusted past full open. Check that there is no foreign obstruction (once found a sparkplug cigarette in a carb and it caused the same problem, who knows how it got there!). Check that the throttle arm on the carb is not loose, there is a clamp screw on it. Run up the engine without the filter installed and see if RPM improves- could be a clogged filter. If this doesn't fix the problem then the timing, compression, exhaust restriction, intake leak and prop suggestions should be followed. How much mag drop do you have? Do you get any backfire? Good luck Bill To: [email protected]; [email protected] From: [email protected] Date: Tue, 31 Mar 2009 13:27:06 -0400 Subject: RE: [ercoupe-tech] RPM at takeoff and cruise altitude >He doesn't have to check his Tach. I didn't mean to imply that the tach was the problem, but It helps to know where we stand. Static RPM is meaningless unless we know the accuracy of the tach. John Cooper Skyport Services www.skyportservices.net _________________________________________________________________ Windows Live™ SkyDrive: Get 25 GB of free online storage. http://windowslive.com/online/skydrive?ocid=TXT_TAGLM_WL_skydrive_032009
