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First I would take the cowling and nose bowl off, remove the spacer on the prop, and run the engine. Is it still rough ? With then nose bowl too tight ??? causing the engine to vibrate aginst it, transmitting vibrations to the airframe..may be the cause. The engine should be free to move inside the cowling. Next, I would recheck the tightness of the rubber bushings on the engine mount. They must not be tight!Maximum torque is very low ( surprisingly ), but necessary to allow engine movement in the rubber bushings....not so tight as to transfer the vibrations to the mount, and to the airframe. See Ercoupe Service Manual, page 42/43...under Engine installation: "1. The 7/16 inch bolts attaching engine to mount are used with rubber bushings to prevent metal to metal contact. Bushings make tensioning of mounting bolts or prime importance. In tightening nuts, apply a torque of 60 - 80 INCH-pounds. After operating engine, and before flight, readjust these bolts to obtain minimum engine vibration. Replace bushings at each engine change." ( Start with 60 inch pounds, and tighten somewhat on vibration test, but not to exceed 80 inch pounds - HLF comment.) Though the book does not say so, (it is assumed you removed the engine and mount as a unit, when removed for service), it is best to install the mount onto the engine before installing the mount onto the airframe. This allows better centering of the bushings, bolts, etc, onto the mount; as there is no weight on the bushings as they are installed. However if using a hoist and sling/chain assy, the engine can successfully be installed onto the already mounted engine mount, but care must be taken to properly place and secure the rubber mounts so there is no excessive displacement of the rubber as the bolts are tightened....not recommended. Also, See Ercoupe Service Memorandum no 28, comments about Flange type crankshafts vs Tapered shaft engines; spinner modifications to give clearance to the cowl, and adjustment of the cowling. Is prop hitting the cowling or the spinner dragging along the cowling ? Best of luck. Fly Safe - Have Fun Harry Francis Elliston, VA N93530 ============================================================================== To leave this forum go to: http://ercoupers.com/lists.htm
