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            Marv,
        You will "squash that insulation big time" using the approach in the     manual.  I didn't like the idea and I wanted a perfectly flat SS     firewall when finished.  The way I accomplished this was to make     spacers which were inserted in the Fiberfrax every place a bolt passed     through.  For the six engine mount bolts I stacked up AN970 washers to     equal the thickness of the Fiberfrax and riveted them together.  For     all other bolts mounting hardware to the firewall, I machined     stand-offs from aluminum rod.  The three layers of Fiberfrax were     glued together and cut to size.  Then I transferred the mounting hole     patterns and used aluminum tubing to stamp out holes in the Fiberfrax     to accept all of the stand-offs.  You have to know where all of your     mounting bolts are going to be located, so I waited to very near the     end to install my SS and Fiberfrax.  In the mean time I had all of my     firewall forward items installed on spacers to position them as if the     Fiberfrax were installed. I didn't glue in the Fiberfrax or the SS.      They are merely clamped in place by every bolt passing through them     and could be removed and modified, if needed.
    In general, it is poor practice to have soft, compliant materials     being compressed by critical fasteners.  In the firewall case, we also     have a sheet of plywood being compressed. So, no matter what you do     with the Fiberfrax, you do not have an ideal joint.  Torque on the     engine mount bolts should be checked regularly because these compliant     materials can creep and cause loss of clamp load.      You will want to stack at least 2 AN970 washers under the nut     otherwise the nut will want to pull through when torqued.  AN washers     are not particularly strong and a single AN970 washer cannot     sufficiently distribute the load when compressing a plywood core.          Chris Zavatson
    N91CZ
        -----
    Marv,
    You can post the above.  I didn't know how what would happen to the     attachment.
    Chris
Attachment Converted: "d:\eudora\attach\chris.bmp"

[Thanks for the detailed explanation and the photos... looks great.  I'll
upload the pics to the LML homepage Attachments area later tonight.  <M>]