On 8/17/2010 1:48 AM, drdlhammond wrote:
The engine in my Aircoupe is a C90-16F. The rubber motor mounts we
removed were the same as the new ones. With 60 inch pounds of torque,
the engine case was in contact with motor mount and the flat washer
beneath the nut had completely flattened out the rubber mount.
*Something** *is wrong. If the engine case is touching the engine mount
then you *will* have a lot of vibration. It almost sounds like your
case is a -14 case. I would take one of the nuts off and pull the
washer and front half of the mount off and look in to see if the case is
conical. I've attached a print showing how it should look. If the hole
through the center is more than 5/8" in diameter, then the rubbers are
getting compressed into the extra space and can't achieve the correct
torque. The relative space between the case and the mount and washer in
the drawing is about what you should be seeing.
I would not do anything (including flying the plane) until this is
resolved. Then I would pull the prop off and re-index it so that when
the engine is between compression strokes the blades are at 10 o'clock
and 4 o'clock when viewed from in front of the plane. This will result
in minimal transfer of power pulses to the sides of the fuselage.
--
John Cooper
Skyport East
www.skyportservices.net
