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Engine Mount Types

Rob Erdos

Well Known Member
Is there a master document somewhere that lists the type of engine mount (conical, Dynafocal 1/2) for each of the myriad Lycoming engine types?

My specific issue...I bought an RV-6 project with an O-320H2AD installed on a mount. I'm selling the engine, and I'm trying to figure out which engines are compatible with the mount that I already have and what types of mounts are required for the various engines that I'm looking to buy.


H mount on the 6

90 % certain the only difference is the arched top rear piece that clears the dual mag. Since there is no diff on the six 320 and 360 mounts, any dynafocal O-320 or O-360 engine should fit.

If you sell the H engine to another RV'er, you can probably sell this mount and buy a new one.

There are some 0 320 dynafocals that are a different angle. The oddballs are mostly Twin Commanche engines, IO 320B and C. There are other o 320 B and maybe C's that are standard dynafocal. The Lycoming publication directory of certified engines covers this and many other issues. If you have a specific model in mind I have the directory. It also lists all cetrified airplanes that a specific engine was used in. Lycoming refers to the two dynafocals as type I and type II.
Slightly Less Confused

Thanks All.

I had seen the Lycoming Certified Engines Manual. It has a wealth of information. What it has to say about engine mounts is as follows:


That's great, but unfortunately it doesn't specify which engine types have which mounts. There are dynafocal Type 1 and Type 2 (geometry of the mounts specified above), but I'm still in the dark about what mount goes on what engine.


P.S. Lycoming: If you're listening, this is way too hard! :(
O-320-A, B and C series are conical
O-320 D, E and H series are dynofocal 1
IO-320 B and C series is dynofocal 2
IO-320 D and F series are dynafocal 1
IO-320 E series is conical
An H2AD mount will normally work for any 320 dynafocal 1 engine but a mount that is made for the other series 320 dynafocal 1 engines may not fit the H2AD engine. As one poster mentioned, the rear case/accessory housing on the H2AD requires a mount with a higher member, in that area, then what is necessary for the other 320 dynafocal 1 engines. Hench, the H2AD Mount has a bit of a hump in that area that isn't necessary for the other dynafocal 320's. It would normally still fit them, because the hump brings more clearance, not less, in that area. A mount made specifically for one of the non H2AD engines may not have enough clearance in that area when used with an H2ADbut then again it might depending on the design. You would have to try it to see.
Hope this helps!
Good Luck and Merry Christmas,
"The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."
Issue Settled

Well, Thanks! That was like finding the Rosetta Stone! Do you think that Lycoming knows all this? Should someone tell them? :)

Sorry, but good information cannot go unpunished

So, if one were to change out an O 320 H2AD to (say) an O 360 A1A, could the engine mount for the H2AD be used for the 360?

So, if one were to change out an O 320 H2AD to (say) an O 360 A1A, could the engine mount for the H2AD be used for the 360?


I just spoke with Ken at Vans today and he told me that the O-320 and O-360 use the same mount (assuming they are both the same type dyno I, II, or conical). However, the cowling is different - at least on the RV-6.