Doug:
(this is my 4th typing of this post,, hopefully it will post this time)
it occurs to me that perhaps we are looking at mounting from the wrong perspective.
the question then becomes from what perspective should we be viewing the problem (assuming it is a problem)
we need to limit movement of the engine? yes. but...
do we need to limit the whole engine? no,,,
or a particular part? yes, that part being the crankshaft
we have three planes to work in and 6 ranges of motion, plus the rocking component
the rocking component is the hardest to address if we think inside the box, and use the commonly accepted mounting method where the
crankshaft centerline (c/l) is well above that of the mount. further the rocking component is worst at critical speeds (that rpm during spin up and spin down that the engine lurches around very pronounced)
so going back to the crankshaft c/l viewpoint, how do we reconcile the rocking motion or make this motion a non factor?
by building a steel frame mount that is U or cradle shaped, where the engine is bolted rigidly to the bottom of the U/cradle and
the rubber mounts are attached at the top of the U/cradle legs, inline with the crank c/l plane, and where the crank c/l is in the
middle of these mounts. this way the rocking motion becomes no factor as it rotates around the crankshaft c/l by design.
we are then left with the three planes of movement and 6 ranges of motion
the vertical plane (up/down) can be addressed effectively by varying the thru bolt torque of the donut rubber mounts, effectively limiting the
up/down motion to within the design parameters by tuning in under operation.
this now leaves the other two planes and 4 ranges of motion, this is where the steel cored donut mounts really shine in that they have sufficient surface area
and contact area with the steel components to limit these two planes and related motions by design.
another part of the donut style mount is the top washers that are used to limit torque action or in this case limit travel during the aforementioned critical speeds of the
engine.
this will work!
i am now convinced that i can design a steel frame mounting system that is resiliently suspended, that does the following
1. makes the rocking component a non factor (+/- .005 or less)
2. limits the vertical motion component, to within whatever parameter i want (+/-.005-.010")
3. limits the fore and aft component, to well within (+/-.005-.010")
4. limits the side to side component to well within (+/-.005-.010")
5. provides for critical speed snubbing,
6. provides isolation from the concrete floor and the related structures.
ok,, GuyF. i know you are out there,,, poke this one full of holes!
this mount would be superior even to a concrete block that has some movement in a clay bed, where rocking motion is evident.
bob g