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Thread: Lycoming O-360/O-320 Dynafocal Mount Dimensions...

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    Registered User mccdhash's Avatar
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    Question Lycoming O-360/O-320 Dynafocal Mount Dimensions...

    Does anybody here on the fourm have any details to the design of the Dynafocal mount used on the Lycoming O-360/O-320 series of engines? I am looking to build my own mount and would like to get some dimensional data for just the "lord" mount part of the mount. I know that you can buy pre-built rings like the ones from Aircraft Spruce, but where is the fun in that!!!!

    Thanks

    mccdhash

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    TFF
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    Re: Lycoming O-360/O-320 Dynafocal Mount Dimensions...

    There is also two different Dynafocal mounts. One focuses on the center of the engine and one the prop flange, so you need to know which one you need to build. Most are 1's.

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    Registered User mccdhash's Avatar
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    Re: Lycoming O-360/O-320 Dynafocal Mount Dimensions...

    After a bit of research, I need the "type 1" dynafocal mount. I found this as well..." Type 1 is used to Lycoming engines up to 180 hp and the type 2 is used in the IO-320 and IO-360 model engines from lycoming."

    mccdhash

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    Registered User mccdhash's Avatar
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    Re: Lycoming O-360/O-320 Dynafocal Mount Dimensions...

    Wow!!! Almost 4 months have gone by since my lost post on this topic. I sure hope that someone out there has some dimensional data on the "type 1" mount. Any help would be great!!!


    mccdhash

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    Registered User Hot Wings's Avatar
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    Re: Lycoming O-360/O-320 Dynafocal Mount Dimensions...

    Dynafocal Model (1).pdf

    Does this drawing have the information you are looking for?
    Conventional wisdom and practices yield conventional results. If that is good enough for you:
    Problem solved.

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    Registered User SVSUSteve's Avatar
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    Re: Lycoming O-360/O-320 Dynafocal Mount Dimensions...

    Quote Originally Posted by Hot Wings View Post
    Attachment 21391

    Does this drawing have the information you are looking for?
    Just out of curiosity does the IO-720 share the same mounts (or at least the spacing/arrangement of the actual attachment points?
    "Unfortunately in science what you believe is irrelevant."- Orion

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    Registered User Hot Wings's Avatar
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    Re: Lycoming O-360/O-320 Dynafocal Mount Dimensions...

    Quote Originally Posted by SVSUSteve View Post
    Just out of curiosity does the IO-720 share the same mounts (or at least the spacing/arrangement of the actual attachment points?
    I really don't know. Its my understanding that there are 2 "standard" Dynafocal mounts and that they differ only in the focal length. I did find this:

    The mounts were changed to reflect the design improvement of the IO-720 (the Big Eight) mount on DWG #63168 dated on 3/15/1966 as Change M.

    There is a 31 degree angle at the center of the bolt in relation to the base of the mount at the bolt pattern. The ID of the mount for receiving the rubber dampener is 1.390/1.380”. Forward to Aft from the face of each washer the measurement is 2.110”. The Ear should be 0.630/0620” thick. Bonded Sandwich Assembly is Lord Part # J-9604-20 which is NOT FURNISHED with engine. Maximum movement to snubbing is 0.27”

    There is also a Lord Part #J-9613-12 and J-9613-15 which is with an ID of 2.015/2.005” and Forward to Aft from face of each washer as 2.760”. These have a 20 degree angle to the base. Subject to change based on bushing used. The ear should be 0.625” thick. Ask your engine rebuilder. Maximum movement to snubbing is 0.46” and this characteristic can create the sag at the prop hub which has been discussed before.

    Both mounts use 0.438” Close Tolerance Bolts.
    Conventional wisdom and practices yield conventional results. If that is good enough for you:
    Problem solved.

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    TFF
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    Re: Lycoming O-360/O-320 Dynafocal Mount Dimensions...

    Not sure about the 720, but the 540s have the mounts backwards from the 4 cylinders. 4 cylinders have the rubber on the mount with the bolt into the engine. the 6 has the rubber on the engine with the bolt into the mount. The 6 mount looks like a dynafocal made for conical mounting rubber.

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    Re: Lycoming O-360/O-320 Dynafocal Mount Dimensions...

    Quote Originally Posted by mccdhash View Post
    Any help would be great!!!
    The Spruce dynafocal ring is worth the price. However, if you have the engine, I can tell you how to machine some spacers that simulate the Lord mount donuts. With those, you would use the metal donut kit from spruce, PN 33253, $99 here DYNAFOCAL ENGINE MOUNT RINGS & KITS from Aircraft Spruce and weld up the metal donuts, bolt them to the engine with the spacers and tack up the dynafocal ring from there. Even so, you still have to bend the tubes to complete the ring. That's why I say the prefab ring is probably worth the price.

    The Spruce ad is not very clear. P.N. 33253 gets you the 8 pieces of pressed cup and the 4 strips around the cups ("rings") to make the four metal donuts. They tig together pretty easily.

    BTW, the complete DF ring from Spruce will not fit an O-320-H2AD. The top tube hits the engine.
    Kent
    -Cozy Mk IV - flying, Long-EZ - 99.9%, BD-5 o-t-g

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    Registered User SVSUSteve's Avatar
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    Re: Lycoming O-360/O-320 Dynafocal Mount Dimensions...

    Quote Originally Posted by TFF View Post
    Not sure about the 720, but the 540s have the mounts backwards from the 4 cylinders. 4 cylinders have the rubber on the mount with the bolt into the engine. the 6 has the rubber on the engine with the bolt into the mount. The 6 mount looks like a dynafocal made for conical mounting rubber.
    Cool...I found out that one of my flying buddies from back in my ultralight days now works as an engineer for Lycoming so he is going to try to get me the data. One of the issues with this design is having to work up an engine mount that has an energy attentuating behavior in the event of an impact instead of an off the shelf mount.
    "Unfortunately in science what you believe is irrelevant."- Orion

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    Registered User mccdhash's Avatar
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    Re: Lycoming O-360/O-320 Dynafocal Mount Dimensions...

    Thanks for the information. The drawing that Hot Wings provided was just was I was looking for. SVSUSteve, if you are able to get any information from your flying buddy, please share if you can.

    Thanks again everyone!!!

    mccdhash

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    Registered User SVSUSteve's Avatar
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    Re: Lycoming O-360/O-320 Dynafocal Mount Dimensions...

    Quote Originally Posted by mccdhash View Post
    Thanks for the information. The drawing that Hot Wings provided was just was I was looking for. SVSUSteve, if you are able to get any information from your flying buddy, please share if you can.

    Thanks again everyone!!!

    mccdhash
    Will do. I am always happy to help in any way I can.
    "Unfortunately in science what you believe is irrelevant."- Orion

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    Re: Lycoming O-360/O-320 Dynafocal Mount Dimensions...

    Would there be any differences in the mount dimensions between the 320 and 360? I was looking at various engine installs on some Breezy airplanes and it looks like the spacing might be larger on the 360 installs. Any thoughts?

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    Re: Lycoming O-360/O-320 Dynafocal Mount Dimensions...

    i have some dimension info call 660-624-0795

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    Re: Lycoming O-360/O-320 Dynafocal Mount Dimensions...

    Hi Guys,

    I am building a 2 seater bi-plane and am preparing to fabricate the motormounts from the firewall to the dynafocal. I will be installling a 360 Lycoming. My understanding of the correct position of the dynafocal is to center it to the aircrafts thrust line. Can anyone confirm taht this would be the proper position? Any comments would be greatly appreciated.

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