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Thread: Stoddard STC for 0-320 on PA-12

  1. #1

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    Stoddard STC for 0-320 on PA-12

    Is anyone familiar with the STC owned by Univair, purchased from Stoddard in the late seventies? It uses a Stoddard 501 engine mount. Stoddards said it is a short mount. What does the STC do with oil cooler, air box, exhaust and cowl? STC # sa83al-501. I'm awaiting a return call from Univair.

    KG

  2. #2

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    Quote Originally Posted by Ken Gabel View Post
    Is anyone familiar with the STC owned by Univair, purchased from Stoddard in the late seventies? It uses a Stoddard 501 engine mount. Stoddards said it is a short mount. What does the STC do with oil cooler, air box, exhaust and cowl? STC # sa83al-501. I'm awaiting a return call from Univair.

    KG
    Hi Ken, did you ever get a response to this? I'm thinking of doing this STC too on my 12

    Thanks

    P

  3. #3
    algonquin's Avatar
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    Would you guys please post your results, I’m just getting started assembling my PA 12, thanks Tom.
    Likes mike mcs repair, Charlie Longley liked this post

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    Charlie Longley's Avatar
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    Pfft just sign it off Tom. Just joking! Which mount are you goin to use?
    Last edited by Charlie Longley; 10-02-2019 at 08:40 AM.
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  5. #5

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    This is from Stoddard Areo Service , Dated 14 June 1973.

    Camera does not work so here it goes.
    Instructions for the following 0-320 series engines in a Piper PA-12, PA-14 Airplane (0-320-A1A,A1b,A2a,A2BA2c,A3A,A3B,A3C, C2A,C2B,C3A,C3B)
    (Includes Basic 0-329) USE M74DM Sensenich Propeller, Minimum51 Pitch

    1.Remove engine, mount etc. from firewall forward, saving only muffler, (If PA-20 or PA-22 exhaust system is to be used) Cowling., carburetor air box and in case of the PA-14, the muffler heat muff, if in good condition.

    2. Install Stoddard Areo Service Engine Mont, Model 501, using the original bolts or new bolts of the original length.

    3 Install 0-320 engine using 4 AN8-44 Bolts. Engine will be baffled and have oil radiator as installed on Piper PA-18-150 as follows, Lycoming P/N 72150 inter-cylinder. (2) 71610 hook, (2) 71611 bracket, (1 each) 14439-00, 14440-00, 14455-00, 14456-00, 14452-00, 14467-00 and (2) 14513 tie-rods, oil radiator is a Harrison ( Piper P/N 455168.)

    4. Install PA-18, PA-20 or PA-22 cross over exhaust system.

    5. Modify carburetor air box by carefully cutting opening in top left rear of the box to accommodate the lower part of the carburetor accelerator pump. Make opening fit closely to prevent entrance of large amounts of unfiltered air. Install air box. Cut carburetor heat and mixture control wire to proper length and connect. Adjust and connect throttle control, connect generator wires, oil pressure line, oil temperature bulb and magneto ground wires. PA-18 air box and filter may be used as optional installation.

    6.Modify the nose cowl by adding oil radiator adaptor ( P/N 13717-00). Clamp nose-cowl to starter gear support using 1/2" spacer blocks for clearance. Cut equal amounts from each end of the channel braces that support nose- cowl. Cut top of cowl to fit ( if baffle felt does not fit tightly against top cowl, replace felt with wider strip), Cut approximately 1.5" from the front of the side cowls and trim to fit.
    Rear of side cowling will not need to be cut. Remove air scoop from lower cowl and move air box opening rearward approximately 1.5" or until it properly fits the air box.
    Slit the bottom cowl down the center from the front of the cowling to the air box opening and overlap to remove excess fullness. Rivet neatly with a row of aluminum rivets spaced about 1" apart. Reinstall air scoop. Provide opening in top cowl for oil filter.

    7. Connect primer and fuel lines, fill with proper grade oil and test run. Engine mount is (3") shorter than standard mount so be shure to use new arm when figuring weight and balance. refer to engine spec. for weight difference. Complete FAA Form 337 stating that installation was made in accordance with STC SA 83 Al.

    8. Approved in land plane, sea plane and ski plane configuration.
    Normal category only.

    Amended Date 14 June 1973



    This is what I have pertaining to the O-320 Instructions for my aircraft that was modified back I the 70;s or 80's.
    This was written as Stoddard sent .

    Hope this helps someone out.

  6. #6

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    There are some other caveats pertaining to floats , a specific type of float is required to use the Modification, as listed in the Operations supplement and also in the drawing - which I do not have ,
    The reason I now this I the AP/IA who did the conversion added 2 lbs. of weight to the tail , the weight may have been related to adding PA-18 Tail feathers. Just do not know as yet.

    If someone has the correct drawing for this modification, could you copy and send to me as I would like to have complete documentation as possible for the records.

    Thanks.

  7. #7
    mworks's Avatar
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    Quote Originally Posted by Kahles56 View Post
    This is from Stoddard Areo Service , Dated 14 June 1973.

    Camera does not work so here it goes.
    Instructions for the following 0-320 series engines in a Piper PA-12, PA-14 Airplane (0-320-A1A,A1b,A2a,A2BA2c,A3A,A3B,A3C, C2A,C2B,C3A,C3B)
    (Includes Basic 0-329) USE M74DM Sensenich Propeller, Minimum51 Pitch

    1.Remove engine, mount etc. from firewall forward, saving only muffler, (If PA-20 or PA-22 exhaust system is to be used) Cowling., carburetor air box and in case of the PA-14, the muffler heat muff, if in good condition.

    2. Install Stoddard Areo Service Engine Mont, Model 501, using the original bolts or new bolts of the original length.

    3 Install 0-320 engine using 4 AN8-44 Bolts. Engine will be baffled and have oil radiator as installed on Piper PA-18-150 as follows, Lycoming P/N 72150 inter-cylinder. (2) 71610 hook, (2) 71611 bracket, (1 each) 14439-00, 14440-00, 14455-00, 14456-00, 14452-00, 14467-00 and (2) 14513 tie-rods, oil radiator is a Harrison ( Piper P/N 455168.)

    4. Install PA-18, PA-20 or PA-22 cross over exhaust system.

    5. Modify carburetor air box by carefully cutting opening in top left rear of the box to accommodate the lower part of the carburetor accelerator pump. Make opening fit closely to prevent entrance of large amounts of unfiltered air. Install air box. Cut carburetor heat and mixture control wire to proper length and connect. Adjust and connect throttle control, connect generator wires, oil pressure line, oil temperature bulb and magneto ground wires. PA-18 air box and filter may be used as optional installation.

    6.Modify the nose cowl by adding oil radiator adaptor ( P/N 13717-00). Clamp nose-cowl to starter gear support using 1/2" spacer blocks for clearance. Cut equal amounts from each end of the channel braces that support nose- cowl. Cut top of cowl to fit ( if baffle felt does not fit tightly against top cowl, replace felt with wider strip), Cut approximately 1.5" from the front of the side cowls and trim to fit.
    Rear of side cowling will not need to be cut. Remove air scoop from lower cowl and move air box opening rearward approximately 1.5" or until it properly fits the air box.
    Slit the bottom cowl down the center from the front of the cowling to the air box opening and overlap to remove excess fullness. Rivet neatly with a row of aluminum rivets spaced about 1" apart. Reinstall air scoop. Provide opening in top cowl for oil filter.

    7. Connect primer and fuel lines, fill with proper grade oil and test run. Engine mount is (3") shorter than standard mount so be shure to use new arm when figuring weight and balance. refer to engine spec. for weight difference. Complete FAA Form 337 stating that installation was made in accordance with STC SA 83 Al.

    8. Approved in land plane, sea plane and ski plane configuration.
    Normal category only.

    Amended Date 14 June 1973



    This is what I have pertaining to the O-320 Instructions for my aircraft that was modified back I the 70;s or 80's.
    This was written as Stoddard sent .

    Hope this helps someone out.
    Hey this just did thank you so much! Ive been looking for details on different option for legal installation with the parts I have on hand and this goes a long way to save on parts.
    PA14, o-320-a2b

  8. #8
    TurboBeaver's Avatar
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    Adding 2 extra pounds of weight is a bit of a mystery when converting from a long mount to a short mount????
    The shorter mount will move the CG aft to start with. So I wonder why the mechanic decided he needed to add aditional weight , if the factory long mount CG was normal , why would need to add weight after installing a 3"
    shorter mount...........
    Good question????
    E

    Sent from my LM-X210 using SuperCub.Org mobile app
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  9. #9
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    Good question Earle. And the answer is that after weighing the plane, that's what he needed to get in into the best CG he could. Remember that no two are alike, and even the short mount doesn't automatically bring it into proper range, especially with maybe the original starter and generator? Going from a 108/115 to the 150 might need nothing, or maybe a couple lbs. or maybe more. Wood or alum. prop? Instrument panel? Original baggage or extended? Front or rear exhaust? Lots of variables. Only the scales will tell you where to go. Something as simple as a screw up when covering and painting the tail feathers requiring an extra quart of paint can change things way back there. I suggest treating them as individual airplanes and do what is needed to get them as right as possible. Too many people ignore proper CG for safety and best performance IMHO.

  10. #10
    supercrow's Avatar
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    And Earle, chances are the long mount CG was not "normal". Most of the long mount 150 conversions can use some tail weight added.

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