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  1. #1
    rainedave's Avatar
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    OS Max-H .40 and "P" Version

    I hope folks don't mind me posting all this stuff!

    Here's a cross flow/baffle piston oldie from the late '60s or early '70s.

    Powermaster 5/29 GMA
    Rev Up 10x6
    12,583 rich of peak
    5.03lbs static thrust
    0.88hp

    This engine would still be good on something like a Sig Kadet Mk II, for example.

    David
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  2. #2

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    RE: OS Max-H .40

    Pretty engine Dave. Another jewel in your collection....
    please send more as you can

  3. #3
    Bone's Avatar
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    RE: OS Max-H .40

    Dave, another great engine, good work! I have 4 of those Max 40H's, both normal ring & dykes ring. Which version is the one on test?

    And no, we don't mind you "posting all this stuff" - in fact, I positively want to encourage you & others to keep doing this - get the old engines out of the cupboard, clean them up & run them [8D]

    I have some Taipan 15's & 21, 2 handfuls of OS engines from the 60's & 70's, Irvine 40's from the mid 80's (23 years ago, so it's sorta old) & sundry others that escape memory at the moment. Better give them a run & report back.
    Saya mencintai aero memperagakan

  4. #4

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    RE: OS Max-H .40

    Hi Dave, just a curiosiy. I was readind some old OS leaflets another day and found a max declared power of 0.85 HP for the H 40, very close to your measuring !
    a later version of this engine had a declared power output of 1.0 HP, in results of a improved carb and bigger bypass
    cheers

  5. #5
    rainedave's Avatar
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    RE: OS Max-H .40

    That's great info. The one pictured has the conventional ring.

    I also have the "P" version, which I believe was timed for pylon use (correct me if I'm wrong). It has two rings. Maybe I'll run that one with a 9x6 and see what sort of HP figure it makes.

    I'm always watching for the "RR" Rat Race version, but I think it was intended for C/L use, not R/C carburetors.

    It would be interesting to compare the sleeves and pistons of all the different types OS produced.

    David
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  6. #6

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    RE: OS Max-H .40

    Nice Dave, please put all this "machinery" to run!!
    i just found the instruction manual from this engine (vintage 40 H), hope that interest you and others pals...

    http://www.rojobcn.com/catalogos/osm...osmaxh4001.pdf

    http://www.rojobcn.com/catalogos/osm...osmaxh4002.pdf

    good luck !!

  7. #7
    rainedave's Avatar
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    RE: OS Max-H .40

    Very cool! Thanks!

    Well, I ran the "P" version. I think this engine has seen too many hours. Maybe a rebuild is in order. It was a bit weaker than the standard version:

    Powermaster GMA 5/22
    Top Flite Super-M 9x6
    14,312
    4.56 lbs. static thrust
    0.84hp

    David
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  8. #8
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    RE: OS Max-H .40

    I’m going to help a newbie into glow engines - perhaps next weekend - and his has the .40 H engine. I’ll post the results when done.

    Would it be harmless to use synthetic oil and no castor? There doesn’t seem to be any manufacture of synthetic oil that recommends mixing castor oil with their oils.

    Thanks :-)
    0% nitro in car fuel? That works! :-)
    http://www.youtube.com/watch?v=ykiffCV4xgk

  9. #9
    rainedave's Avatar
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    RE: OS Max-H .40

    It depends on the type of synthetic oil in your fuel. Here in the US no one in their right mind would ever run an old engine like the Max-H with anything other than castor oil. However, I understand that in Europe there are synthetic oils that are comparable to castor. I think Aerosave is one of them. Even with the high quality Euro-synths make sure you have at least 22% or more oil in your fuel. If it is a new engine that you will be breaking in, then make sure you have at least 25% or more oil, 28-30% would be better. This is a 40yr old design. Please don't treat it like a modern engine.

    David

  10. #10
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    RE: OS Max-H .40

    Thank you very much, David.

    Yes, I've AeroSynth3. It's a used engine, so I mix some fuel with 25% oil.

    To be continued :-)
    0% nitro in car fuel? That works! :-)
    http://www.youtube.com/watch?v=ykiffCV4xgk

  11. #11
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    RE: OS Max-H .40

    Hello gentlemen.

    Well, it was an OS Max .40 FSR engine. I’m not sure about the prop size, so the RPM is useless. Fuel: 25% castor and 75% methanol. Rossi 3 plug was too cold (2 degree Celsius). OS F was perfect. The engine ran just great, but once again, a little nitro would make it perfect.

    10500 RPM
    0% nitro in car fuel? That works! :-)
    http://www.youtube.com/watch?v=ykiffCV4xgk

  12. #12
    rainedave's Avatar
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    RE: OS Max-H .40

    A 10x6 is the correct prop. I would think you should get between 13,250 and 13,750 with the stock muffler.

    David

  13. #13

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    RE: OS Max-H .40 and "P" Version

    Dave, I just picked up a very nice used MAX-H .40 that looks exactly like yours. I'm guessing it was one of the final issue before the .40fsr and then .40SF came on to the scene.

    This MAX-H 40 does have one weakness, and it is the rod. It has no bushings, none. On the other hand, this engine does have a nice fully machined billet steel crankshaft, I think this crank would be cast if it were made today by OS.

    If it weren't for the unbushed rod, this engine would run just fine on cool power, gads, did I say cruel power???[:@]

    I wonder if a 40 FP/LA bushed rod would fit into this engine. Isn't the same rod also shared with the 40fsr? I seem to remember it does interchange?


    Mike

  14. #14
    rainedave's Avatar
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    RE: OS Max-H .40 and "P" Version

    I'm 99% certain that the FP rod is the same as the FSR. I'm not sure about the Max-H rod. At any rate I only use fuel with lots of castor in all my oldies.

    Run yours up and see if you get similar performance as me. I thought .88hp at 12, 583 was pretty decent for an old cross-flow sport engine.

    David

  15. #15

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    RE: OS Max-H .40 and "P" Version

    I will get out and run it as soon as it warms into at least the 40's. I will be happy if I get performance similar to yours.

    Pics and R numbers to come.......

  16. #16
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    RE: OS Max-H .40 and

    Guys

    Glow Newbie here. Thought I could wake this thread up and perhaps gain some of the knowledge you gentleman seem to have.

    Today I acquired a Sig Kougar that someone poured a lot of sweat into finishing the model. No doubt this model has been flown, but it is still in very reasonable shape.

    For Power it also has one of these OS Max H motors. Stamped in a circle on the motor is 40P. So I assume it's one in the same with the motor you were talking about.

    The motor sports a OS 703 muffler. My question is do you fellows feel this motor is suitable to fly the Kougar? Also would the motor benifit from replacing the stock muffler with a tuned pipe to gain some more RPMs.

    Thank You very much!

    Tommy
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  17. #17
    jeffie8696's Avatar
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    RE: OS Max-H .40 and

    Use a fuel with lots of castor, Sig makes a 25% castor fuel that works fine.
    Then fly it and be happy. the plane was most likely designed around that engine. Use an idle bar plug too.
    Club Saito # 677-Team Boca Bearings-Star Collectibles Muscatine-Glowhead Brotherhood #19

  18. #18
    _Tommy D's Avatar
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    RE: OS Max-H .40 and

    Thanks!

    Hey inspecting the motor/mount tonight I notices this. Looks like the mount was modded for some reason. I understand there are some brands of flexible mounts, but this can't be one... can it???

    Would you agree this engine needs a new mount ASAP?

    Tommy D
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  19. #19
    jeffie8696's Avatar
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    RE: OS Max-H .40 and

    Ithnk that one is a little TOO flexible.
    Club Saito # 677-Team Boca Bearings-Star Collectibles Muscatine-Glowhead Brotherhood #19

  20. #20
    _Tommy D's Avatar
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    RE: OS Max-H .40 and

    FWIW I ran up the old motor today and Ill be damned but it runs pretty darn good. Has a nice low idle and even revs up ok. I did not have a tach on me, but my ear says not too shabby!
    http://tommydsblog.blogspot.com/

  21. #21
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    RE: OS Max-H .40 and

    ORIGINAL: _Tommy D
    Stamped in a circle on the motor is 40P.
    There are two basic types of H40 engines. The one shown in the first post is the second type and was the last of the H40's having a much wider transfer bulge, twin ballraces and came only as H40. The first of the H40's had the narrower transfer bulge and most were only a single (rear) ballrace and a different prop driver that recessed back into the crankcase where a front ball race would go. The first type was available in several different configurations. The RC was just marked as 40, the CL version was marked as 40S (I have one of them), then there was the version made for CL rat racing which was marked as 40RR and the final one was the 40P for pylon racing. The 40P was the only one to have twin ballraces so had the same prop driver as the later version. I don't know about port timings but my bet would be that the 40 and 40S were the same while the 40RR and 40P likely had the same (altered) timings. The RR and P would be the rarest of all H40's being competition engines.

    One other difference between the first and second types is that they had different bores/strokes so not much is interchangeable.

  22. #22
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    RE: OS Max-H .40 and

    No reason that engine wont last a long time given enough castor. And if you like the way it runs enjoy it. I for one would love to see some video of a flight .
    Club Saito # 677-Team Boca Bearings-Star Collectibles Muscatine-Glowhead Brotherhood #19

  23. #23
    _Tommy D's Avatar
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    RE: OS Max-H .40 and


    ORIGINAL: jeffie8696

    I for one would love to see some video of a flight .
    Ill see what I can do. Last night I placed a few mounts on order so it might be a weeks time before I get the Kougar back together.

    In general I'm usually the guy behind the lens at my field. Perhaps I can find someone to fly it for me while I shoot stills first, then do HD video.

    Photo from last sunny day here in NY

    Tommy D
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  24. #24
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    RE: OS Max-H .40 and

    Nice shots. If you were close to MD I would tell you to go see my buddy Joe. He can fly just about anything I think.
    Club Saito # 677-Team Boca Bearings-Star Collectibles Muscatine-Glowhead Brotherhood #19

  25. #25

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    RE: OS Max-H .40 and

    An old 'ish post I know - but i had to say.......... I recently sold my 30 year old Max H 40 with a vintage model, in which the old engine happily turned a 13x5 at around 7800 and sounded sweet doing it.  My engine had never had a starter on it and i could almost guarrantee a start on the first finger flick when primed just how she liked it.

    When i see so many 'modern' engines being ground away with a starter  for ten seconds at a time before firing and then running erratically i do wonder whether engine designers have lost their way.

    I do still own a never flown OS 40 FSR ABC from the eighties - lovely motor.......


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