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Old 07-14-2017, 01:12 PM   #26
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Garyg,

I've been running into a similar headache with our S-1-11B, and to be honest I'm still confused.

We have large engine ears on our C4B5, p/n 72306, and everything appears to fit. The engine mount/frame was made to plans as far as I am aware. We're using LORD J-7764-31 rubbers

The problem we have now is that the large ears are too tall for the Wolf Cowling. Are you saying that you've found some small ears that will fit the stock engine mount/frame?

And if I have the large ears with stock, is this type 1 or type 2? I'm finding conflicting information on that too!

Alexc,

If you have a per drawings mount, you will need the 20 degree, Type II dynafocal mounts ears as you have now. However I was informed by Josh that on another plane (in the UK as well?) where they put on Wolf cowling they had to put bumps in the cowling for clearance of these ears. I am sure later in the day Josh will chime in here. That is pretty much the extent of my knowledge on the Wolf cowling. The isolators you used match the ears and the stock mount.

My mount was built to dynafocal Type I and therefore uses the smaller, small bore hole mount ears and a different isolator to match. I sort of had to deduce that. If you want to verify the mount type you have, just extend a line to the focal. The difference is vast (16 inches or so vs 32 inches), so you don't need to be very exact about it. If the mount looks like the converge is almost to the prop, it is Type II.

gjg



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Old 07-14-2017, 01:22 PM   #27
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Gary,

I replaced mine about a year ago with Barry Mounts, P/N 94016-40. As I recall, they were not the original mount but we called around and determined that they were the equivalent.

No problems at all.

Thanks


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Old 07-14-2017, 01:36 PM   #28
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Rather than put bumps on the cowling, I wonder if some 20 ears could be machined that were designed to accept the smaller Lord mounts. That would reduce the height of the ears but would it be enough? I'm thinking the larger Lord mounts were used to support the heavier IO-720 engine and the normal smaller Lord mounts would be OK in this application. Or maybe Lord would have an alternate suggestion for hybrid ears on an O-540....
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Old 07-14-2017, 01:37 PM   #29
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Gary,

I replaced mine about a year ago with Barry Mounts, P/N 94016-40. As I recall, they were not the original mount but we called around and determined that they were the equivalent.

No problems at all.

Thanks
Avalanche,

I think that is a small bore isolator (1.375 inches) and is a Type I dynafocal. If that fit, I dont think your mount was built to plans. I think I was considering that as well before going with the Lord mounts.

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Old 07-14-2017, 01:44 PM   #30
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Originally Posted by cwilliamrose View Post
Rather than put bumps on the cowling, I wonder if some 20 ears could be machined that were designed to accept the smaller Lord mounts. That would reduce the height of the ears but would it be enough? I'm thinking the larger Lord mounts were used to support the heavier IO-720 engine and the normal smaller Lord mounts would be OK in this application. Or maybe Lord would have an alternate suggestion for hybrid ears on an O-540....
Bill,

I am quite sure machining the large ears down to the size of a small ear would not be possible. The size difference is pretty significant when they sit side by side. If what I understand is correct, they wont have much choice other than to put bumps in the cowling or make a new mount and buy new ears and isolators. My apologies if I misunderstood some of my email traffic on this. Even with small ears on mine and stock cowling it looks frightening...


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Old 07-14-2017, 02:48 PM   #31
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I wasn't thinking to modify the large ears into small ones, I don't think that would be possible given the metal that's missing from the large hole. I'm talking about machining new parts from billet.
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Old 07-14-2017, 03:02 PM   #32
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Alexc,

If you have a per drawings mount, you will need the 20 degree, Type II dynafocal mounts ears as you have now. However I was informed by Josh that on another plane (in the UK as well?) where they put on Wolf cowling they had to put bumps in the cowling for clearance of these ears. I am sure later in the day Josh will chime in here. That is pretty much the extent of my knowledge on the Wolf cowling. The isolators you used match the ears and the stock mount.

gjg
Thanks, that's very helpful and verifies what we have. We are thinking of putting some bumps/blisters in the cowling, just hope it visually looks ok. I don't think we're in a position to start changing the engine mount/frame here, it will be a long, long process with the LAA.
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Old 07-14-2017, 03:45 PM   #33
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I wasn't thinking to modify the large ears into small ones, I don't think that would be possible given the metal that's missing from the large hole. I'm talking about machining new parts from billet.

Bill,

Now that I think about it, I bet if one was willing to create a small bore 20 degree mount from a billet, that would be quite doable and then just use a Type I isolator. I think that would work because then you could shave off that top but maintain the center. I dont think you could stick to a Type II isolator is all.

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Old 07-14-2017, 04:04 PM   #34
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Are the focal mount hole centers further out from the case on the big mounts? Machining small hole case mounts at the different angle will not help?
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Old 07-14-2017, 04:10 PM   #35
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Are the focal mount hole centers further out from the case on the big mounts? Machining small hole case mounts at the different angle will not help?
Yeah the center is moved out from the 20 degree but I am thinking (I think Bill is way ahead me...) that you could maintain the center of the 20 degree 2 inch bore but only machine it to 1.375 inches for a Type I size isolator. That way you could remove a significant portion of the ear as extra material (0.375?).
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Old 07-14-2017, 04:36 PM   #36
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Now you got it Gary. But it's only worth considering if it allows you to use the Wolf cowling without adding blisters.
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Old 07-16-2017, 09:00 PM   #37
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I took a picture of mine with Barry mounts and large bore lug. 1/2 to 5/8 inch clearance with a plans built cowl. Not sure how much clearance with a Wolf cowl.
eng mount lug ear  1.jpg   eng mount lug ear 2.jpg  
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Old 07-17-2017, 01:22 AM   #38
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Dan,

Looks like plenty of room. I just know what I was told about the Wolf cowling and the large ear and it appears that this isnt the only one with issues. The large flat washer, is that part the isolator. I am trying to order up bolts and my calculations with one AN960 and the nut put me right at AN7-52. If I put a AN970 I should probably go to AN7-53 or 54. Except they don't seem to make that bolt. ACS goes next to -56 which would require a lot of washers. Some places suggest that they might exist (none in stock) but they are a whopping 28 bucks a bolt!
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Old 07-17-2017, 01:30 AM   #39
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I used the large diameter mounts from Van's Aircraft and their bolt kit......no problems.

Bob
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Old 07-17-2017, 01:43 AM   #40
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I used the large diameter mounts from Van's Aircraft and their bolt kit......no problems.

Bob
My mount was built to Type I dynafocal as opposed to the plans specified Type II. So mine would use an isolator similar to the RV-10 (which uses a softer J-3804-28). The bolts are also a lot shorter (I think) because they go inside the attaching tube. This lets them use shorter bolts. The plans built S1-11 mount would be the same as Harmon Rocket. Not sure what bolts they use.


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