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Thread: 912 exhaust and muffler/cowl clearance

  1. #1

    Join Date
    Aug 2017
    Location
    Coal Point, NSW
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    19

    Cool 912 exhaust and muffler/cowl clearance

    Upgrading MKII from 532 to 912.

    912 is unused but older model.

    The rotax exhaust that came with the engine has slip joints with tension springs between headers and muffler, no ball joints like on the later 912 exhausts, the slip joints are very tight.

    I’m In the process of extending the cowls for the 912, 1.75inch extension required and cowl is jigged and ready to splice the extra length on.

    The muffler literally sits on the bottom cowl, so while I’m doing the glass work I want to add a bubble to give at least 1 inch of clearance.

    A) does anyone have experience with this older type exhaust without ball joints? Is it a complete nightmare and is there any recommendations to improve it, low cost simple solutions preferred.

    B) what have people done to get better 912 muffler -> cowl clearance.? My strategy at this point was to lower the entire bottom section 1 inch curving back up to overlap rewards and rest/sit flush the stainless steel belly/firewall plate.

  2. #2
    Senior Member HighWing's Avatar
    Join Date
    May 2009
    Location
    Goodyear, AZ
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    1,743

    Default Re: 912 exhaust and muffler/cowl clearance

    I have flown IVs. Cowl clearance about an inch. Joints a non issue with the early round cowls, however it is wise to use a separating compound to prevent binding at the slip joints due to the heat and corrosion. I used a graphite containing anti-seize lubricant. Aircraft Tool Supply Company ATS2612 It is a spark plug thread and anti-seize lubricant.

    And to prove my age, I think I have come to believe that all that is new may not always be better.
    Lowell Fitt
    Goodyear, AZ


    My You Tube Channel

  3. #3

    Join Date
    Aug 2017
    Location
    Coal Point, NSW
    Posts
    19

    Default Re: 912 exhaust and muffler/cowl clearance

    Hi Lowell,

    Thanks for the sage advice, I’ll use some lube on the joints, they are already very tight so I will polish them down a bit before reassembly and build cowls out to give 1’2 Inch clearance.

    Nice videos on your YouTube channel by the way..

    Kind regards,

    Rob.

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