Hi Paul-

The machinist is concerned that the new rear engine mount has too much
of a moment arm on the long tube.  He wants to weld a gusset on it 3/4"
from the end over to the vertical that ties into the engine.  He's also
somewhat concerned about the strength of the mounting points on the
engine & whether they might crack off the front cover.  What say you?

Mark & Mark

I assume this is the one in question.
Have him weld it up. Install the ball joint and the 1/2 inch bolt
with washers under the head and nut. Torque the 1/2 inch bolt down to 500 to
800 inch pounds or so. Then weld up a front cover simulator/rear mm test
bracket out of 1/4 inch steel that looks something like this sketch.
You could also use a chunk of channel iron.

Attach this bracket to the new rear motor mount. Connect the bracket
with the hook on an engine hoist. Connect the 1/2 inch rod end shank
to any convient car or truck large engine lying around and use the hoist
to lift the engine. Remember there is only 60 pound load on
this bracket under static conditions and 360 pounds on a 6 G hard
landing or pull up. The rest of the airplane may not take 6G.

As to the ears on the front cover. A simliar system was used on the
12A front cover to mount most of the engine weight and some of the
transmission weight as the only other mount was under the rear of
the tranmission.

Never the less one could tie the new tubular mount  into the
oil pan bolts under the oil pan rail as in the last illustration.
Make a strip of 1/8th thick steel of about six inches long
and 3/4 of an inch wide and insert it under the the heads of the oil pan bolts.
Then make the vertical strips welded around the 1-1/4 OD tube
into a sort of a hook that wraps around under this strip of steel.
Weld them together. Assemble it and then match drill the holes
in the front cover.

Paul Lamar

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