Hello Fred:

Yes, replacing the windshield in my IV-P gave me the opportunity  to address the loose engine mounting bolt problem since I had removed the instrument panel and had a chance to access the back of the firewall (although in a somewhat limited way).

Originally I had planned to reverse the bolts and then somehow secure the boltheads  to inside of the firewall but soon gave up that idea.

 I think that the ideal solution would be to design an "L" shaped bracket that would capture the nut on the mounting bolt on the back of the firewall while the "L" shape would provide an easy way to secure the bracket to the side of the fuselage with hysol andl carbonfiber. to prevent rotation.  Gave up that idea because there wasnt enough room available behind the firewall without pulling out everything.  This might be a good solution for a new build,

I then had some special (1-3/4")washers made an with hexagonal shaped opening designed to capture the nut but still needed something additional to address the shearing moment between the nut/washer and the firewall.  Since space is very limited, I am making some  larger washers (2-1/4") and will tack- weld the special washers to the larger washers.  The idea is to cut out spaces in the exposed edges of the larger washer to provide the hysol some additional edges to bond to..  After I bond the washer assembly to the back of the firewall, I will cover with a couple bid of carbonfiber.

Thats the current plan but always subject to change as the thinking process continues.  Comments would be appreciated.

Regards, Bill Hogarty