Backcountry Pilot • Nose bowl problem on my C170b 180hp Avcon conversion

Nose bowl problem on my C170b 180hp Avcon conversion

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Nose bowl problem on my C170b 180hp Avcon conversion

hotrod150 wrote: I did see that Harry Dellicker passed away early this month at age 82. Too bad-- I never met him in person but I did have a (long) phone conversation with him years ago and he really knew his stuff.


That's too bad... A wealth of knowledge quietly disappears.
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Re: Nose bowl problem on my C170b 180hp Avcon conversion

Glidergeek - I'll double check where the mount attaches to the firewall to make sure those bolts and the rubber pads there are in good shape, too.

I'll check with my IA on getting the part numbers for the bushings, I was just trying to order them without having to move from my computer!
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Re: Nose bowl problem on my C170b 180hp Avcon conversion

Most of the 180 conversions I have seen in 170s only use a flat washer at the firewall. - No rubber.

On mine - the old "BUSH" conversion - there are large flat washers between the mounts and the engine on the left side - top and bottom.

You may be able to the best answer from another Chris if he is still running any of the business at Del Air.

I will dearly miss old Harry. Spent many a long day there - mostly listening - learning actually. Harry was the one that helped me get field approval for VGs on the vertical of my 170B. Why? Just because we could. I believe Harry's last flight was to fly up to KRHV to inspect and sign-off my log book for the long range tanks he sold me. That was the implication he gave. Still rode his Harley at that time.

Tears to ya Harry.

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Re: Nose bowl problem on my C170b 180hp Avcon conversion

I think there is a solid aluminum block that replaces the rubber mounts between the mount and the firewall. I think it is a 180/185 seaplane part. I tried posting a photo of mine and a Del Air nose bowl but am experiencing technical difficulties or it operator error.

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Re: Nose bowl problem on my C170b 180hp Avcon conversion

I'd be willing to bet that my IA could give you the part numbers. He replaced the mounts on my Avcon converted P172D, and I remember it took him awhile to find the right ones. I've had no difficulty with engine movement since he replaced them several years ago. Call him Monday at nine seven oh, two one eight, three seven five eight--Jim. Tell him I referred you, and give him several days to look them up. He's a good guy.

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Re: Nose bowl problem on my C170b 180hp Avcon conversion

The part numbers for the float plane bushing at the firewall is 0751004-1 and 0751004-2. You need 4 of each and I think they will cost you $160/corner, so $640 total. I am thinking about getting PMA on these, but it is a low priority project so it will probably be a year or more before I get to it.

The part number for the mounts at the engine is J-3804-28. You'll need 4 of these as well, and the best deal I found on them was around $190/corner. Don't forget the AN970-7 washer between the mount and the engine on the LOWER mounts only. I've seen more than one airplane with these missing and that can contribute to the engine sagging.
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Re: Nose bowl problem on my C170b 180hp Avcon conversion

AEROPOD wrote:Don't forget the AN970-7 washer between the mount and the engine on the LOWER mounts only. I've seen more than one airplane with these missing and that can contribute to the engine sagging.


I guess to be more accurate, these missing will contribute to the engine not being aligned properly in the cowl, not sagging.
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Re: Nose bowl problem on my C170b 180hp Avcon conversion

Thanks for all the information and part #'s. As far as I can tell by looking, my engine mount at the firewall uses some sort of rubber bushing. Here is a photo:

Image

Are you saying that this should be an aluminum spacer of some sort?

I'll make sure the lower engine bushings have the washer next to the engine as well.
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Re: Nose bowl problem on my C170b 180hp Avcon conversion

amacbean wrote:Thanks for all the information and part #'s. As far as I can tell by looking, my engine mount at the firewall uses some sort of rubber bushing. Here is a photo:

Image

Are you saying that this should be an aluminum spacer of some sort?

I'll make sure the lower engine bushings have the washer next to the engine as well.


According to Cessna, the rubber is fine, but the 180 uses the same rubber mount, except for seaplane applications where the rubber bushing is replaced by an aluminum one. Cessna seemed to believe that under heavier use (seaplanes for example) that the rubber was less than adequate. This was only true on the 180, and the aluminum bushing are never listed in any 170 parts book I've ever seen. Somewhere along the line somebody figured out that the rubber bushings were the same part number on 170s and 180s, then they decided if the aluminum bushing would fit a 180, it would probably work backwards to the 170.

So "should" you have an aluminum bushing? Not according to any cessna or Avcon drawing I've ever seen. But is it a good idea? Most folks seem to think so.

My advice, buy one corner from cessna, and copy it 3 times.
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Re: Nose bowl problem on my C170b 180hp Avcon conversion

The 2 bottom rubber bushings on my 180 would last 400-500 hours, the top 2 bushings lasted about 1000 hours. Went to an AWI seaplane mount and the metal seaplane bushings 175 hours ago, IMO a much better setup.
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Re: Nose bowl problem on my C170b 180hp Avcon conversion

amacbean wrote:Does anyone have the part # for the engine mount bushings on the Avcon 180hp conversion in the 170? Our is the 0-360 A1A engine. I can't seem to find the numbers in the paperwork, and I can't see a number stamped on the bushings themselves. It's probably on the side that is to the engine and I would have to pull one of them to look at it. Here is a great cell phone photo of one of the top bushings for reference:

Image



Just in case you're still looking for the part numbers ...
The engine mounts are Lord p/n J-3804-28. That p/n refers to an assembly that consists of three pieces: 2ea. J-3049-35 bonded mounts (the two big donuts) plus 1ea. J-12333-2 spacer. The only part number you can see when the assembly is installed on the airplane is J-3049-35.

The J-3804-20, -27, and -28 assemblies all use the J-3049-35, but different spacers.
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Re: Nose bowl problem on my C170b 180hp Avcon conversion

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