Dynafocal Engine Mount Bolt Lenght Question

[stretchedpacer]

I am building a bushmaster and am about to install an O320 that has the most common dynafocal mounting (type 1?). In any event, I bought the aerobatic homebuilder's mounts from aircraft spruce and AN7-43 and AN7-44 bolts called out in all the parts diagrams I have access to. When I install the mounts and measure the bolt length compared to the thickness of the flange on my O320 I find that the bolts are maybe 1/2 inch too long. I don't know how far these mounts compress when tightened but it seems I need a grip length of no more than 3.25 inches (maybe less?).
So, the question is does anyone know the bolt length from past experience. I would rather avoid the option of buying 6 different bolt lengths in an effort to find the right one. Any help would be greatly appreciated.

[MN_flyer1]

I could be wrong but I thought the Dynafocal mounts had a center bushing that was torqued upon. The conical mounts are tightened to a specific compression length.

[stretchedpacer]

I could be wrong but I thought the Dynafocal mounts had a center bushing that was torqued upon. The conical mounts are tightened to a specific compression length.
Generally speaking you are correct. My question is the bolt length however as the bolt length shown in all the plans I have reviewed is AN7-43 and AN7-44 (top and bottom). You cannot torque the mounts with these bolts since the bolts are easily half an inch too long. These lengths are incorrect for the aircraft spruce aerobatic homebuilders dynafocal mounts. Since there seems to be no knowledge about the combination I ordered the full compliment of bolt sizes today and will go through them until I find the right fit. I will then post it here in the hopes that it may save someone a headache later down the road.

[MN_flyer1]

Ah makes more sense. Does seem like it would be a "by the book" setup though. I am not too familiar with Dynafocal systems. Hopefully someone here can help you out.

Tim

[Jim]

Hi,

I'm using a dynamical mounted 0-320 in my Pacer, but it is the Univair mount, so my install info probably wouldn't have helped you.

[rocket 204]

hello i have a set of barry rubber cushons for the dynafocal mount of a beech c23 muskateer they have an aluminum spacer between the two rubbers , the bolts are an7 and are 3 9/16 inches long total length which i would guiese would make them around a -34, these were used on the lycoming 0 360 but i don t think the mount boss on the 0 320 is any different

[stretchedpacer]

Thanks for the response Rocket. You were right. The AN7-34 will work for this installation. Thanks!