Bulent Aliev wrote:

On my 22003 mounts I made Delrin inserts with 5/16 bolt hole and pressed them in. This
way I can use smaller and much lighter AN bolts.
Bulent

I think you are a bit on the small side there Bulent.
Try 3/8 or 7/16.

Paul Lamar

Bulent Aliev wrote:

Per plans mount needs only 1/4" AN bolts at the firewall.

Yikes! I would not want my engine to fall off. If it throws
a blade I think you might want larger bolts. Kind of hard to glide
with the missing weight of the engine.

Paul Lamar

Bulent Aliev wrote:

I had a conversation this morning about that with the owner of Fighter Enterprises in Ft
Lauderdale. He maintains and repairs Mustang P-51's  mostly. He thinks even 5/16 is over kill.
Also in the Cozy the thrust forces are against the Barry mount, and not against the bolt, like
the tractor config. Also I looked at a Mooney mount. Again 1/4" bolts  on the firewall and the
thrust works against the threads on the same bolts?

Wow. My Cessna uses 3/8 or 7/16 I don't remember exactly which.... maybe 1/2 inch.

Push or pull matters not in a six G pull up or a hard landing.

Are you using the "rubber bushing in the firewall trick" Bulent? If not
then are we talking about the bolts holding the steel mount to the firewall
or the bolts going through the rubber bushings mounts out near the engine?
If out near the engine the bolts are in a bit of bending mode while the
ones holding the steel mount to the firewall are mainly in shear and
tension. That makes a difference. I personally would not use 1/4 or 5/16 bolts
anywhere in the engine mount. Not worth the risk for such a small increase
in weight.

Paul Lamar

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