RE: mvvs 1.60 gasser  
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    • All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> Gas Engines >> RE: mvvs 1.60 gasser
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    RE: mvvs 1.60 gasser - 5/14/2008 10:06:51 PM   
    RevGQ



    Posts: 348
    Joined: 9/15/2002
    From: Alta Loma, CA, USA
    Status: offline     		My engine is inverted in a P40 Warhawk and I simply use a small plastic bottle with fuel tubing attached to squirt fuel into the carb.


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    8774 Monte Vista

    (in reply to Wiltshire1)
           Post #: 1426

    RE: mvvs 1.60 gasser - 5/15/2008 12:51:38 PM   
    makib


     

    Posts: 3
    Joined: 2/17/2008
    From: logatec, SLOVENIA
    Status: offline     		Hi,
    I have also MVVS 1.6 inverted on my F3A plane with original reso on and turns 17x10 Mejzlik abouth 8000rpm and more! great engine. For first time starting after long period close choke, make abouth 10-20 flips (no contact), switch on and fire at once shortly, release choke, after fev flips will run, make shure not to push hard throttle at once, let motor get working temperature.
    Hope this will help.

    ps
    my motor is with red had and 2 magnets, previous was wit 1, but this is muuuch bether! much more tork in lower rpm.
    when I have a little time I will post some pictures.

    (in reply to RevGQ)
           Post #: 1427

    RE: mvvs 1.60 gasser - 5/15/2008 3:37:19 PM   
    RysiuM



    Posts: 1400
    Joined: 4/22/2003
    From: Elk Grove, CA, USA
    Status: offline
    quote:

    ORIGINAL: makib
    For first time starting after long period close choke, make abouth 10-20 flips


    Like I wrote, it would take more than 20 flips (it will be more than 1000 flips) to get the fuel to the carb. I admit, that the fuel tank is about 10 inches behind the engine, but still the fuel moves in the line very slow. Comparing to my other engines, where every flip the fuel moves about 1/4 inch in the line for every flip, in MVVS I can't see any movement in the fuel line. Once the carb is wet, it draws the fuel without problem. Maybe my carb is bad (it was always like that) or maybe I should open the pump cover and check the membrane for contamination.

    I think I have the same version (red head, two magnets, Vlach ignition). Once it starts the engine is awesome.


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    AMA Gold Leader Club, Charter #1243, Sacramento, CA

    (in reply to makib)
           Post #: 1428

    RE: mvvs 1.60 gasser - 5/16/2008 8:58:47 AM   
    makib


     

    Posts: 3
    Joined: 2/17/2008
    From: logatec, SLOVENIA
    Status: offline     		maybe is the carb. pump sealings old, (maybe the carb. was sitting in store a few years before come to sit on your engine),
    change all the carb. sealings-(2 pieces) will help for shure. Replacing is wery simple, one big screw and 4 smaler. Of course, some cleannign will help also, specially small metal net down in abouth 8mm hole. This net is wery ofen sealed with dust and old oil.
    This is just sugestion for solwing some minor problems which offen occurs.

    (in reply to RysiuM)
           Post #: 1429

    RE: mvvs 1.60 gasser - 5/16/2008 5:17:42 PM   
    RysiuM



    Posts: 1400
    Joined: 4/22/2003
    From: Elk Grove, CA, USA
    Status: offline
    quote:

    ORIGINAL: makib
    Replacing is wery simple, one big screw and 4 smaler.


    I guess, I will have something to do this weekend
    BTW, I just fired up Fuji BT-43EI-2 , on my Wilga - the first time since January 2008. The fuel setup is identical to my MVVS (tank is about 12 inches behind and about 5 inches below the engine). Five flips on the prop and the engine came to live. No problem with the fuel drawing here. That proves, it is not the setup fault, but the carb itself. I will open the carb and see what's going on (it's pita, as I have to disassemble the whole front end of my Edge in order to get into the carb now).


    _____________________________

    Mather Aerospace Modelers, Inc.
    AMA Gold Leader Club, Charter #1243, Sacramento, CA

    (in reply to makib)
           Post #: 1430

    RE: mvvs 1.60 gasser - 5/16/2008 9:39:42 PM   
    PlaneKrazee



    Posts: 3541
    Joined: 5/15/2002
    From: Westerly, RI, USA
    Status: offline     		It's been a while since looking at my 26 but did you seal the hole (if there is one) in the choke plate?

    Regards,


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    KB1DTB
    AMA11123

    (in reply to RysiuM)
           Post #: 1431

    RE: mvvs 1.60 gasser - 5/16/2008 10:02:44 PM   
    RysiuM



    Posts: 1400
    Joined: 4/22/2003
    From: Elk Grove, CA, USA
    Status: offline
    quote:

    ORIGINAL: Skypilot_one
    It's been a while since looking at my 26 but did you seal the hole (if there is one) in the choke plate?


    No need for that. This is the pump or mettering device causing the problem, not that the engine gets to much air.


    _____________________________

    Mather Aerospace Modelers, Inc.
    AMA Gold Leader Club, Charter #1243, Sacramento, CA

    (in reply to PlaneKrazee)
           Post #: 1432

    RE: mvvs 1.60 gasser - 5/16/2008 11:36:49 PM   
    Antique



    Posts: 656
    Joined: 7/14/2002
    From: Irvine, CA, USA
    Status: offline     		The pump functions only after the engine is running and gets the pulse from the crankcase...
    The choke is a separate function..A plate with no hole at all works just like a thumb over the venturi...The hole lets air through....You don't want air, you want fuel from the tank....

    (in reply to RysiuM)
           Post #: 1433

    RE: mvvs 1.60 gasser - 5/17/2008 12:38:11 AM   
    PlaneKrazee



    Posts: 3541
    Joined: 5/15/2002
    From: Westerly, RI, USA
    Status: offline
    quote:

    ORIGINAL: RysiuM


    quote:

    ORIGINAL: Skypilot_one
    It's been a while since looking at my 26 but did you seal the hole (if there is one) in the choke plate?


    No need for that. This is the pump or mettering device causing the problem, not that the engine gets to much air.



    If you put your thumb over the carb and flip the prop does it suck fuel? Solder over the hole.

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    KB1DTB
    AMA11123

    (in reply to RysiuM)
           Post #: 1434

    RE: mvvs 1.60 gasser - 5/17/2008 12:39:18 AM   
    PlaneKrazee



    Posts: 3541
    Joined: 5/15/2002
    From: Westerly, RI, USA
    Status: offline
    quote:

    ORIGINAL: Antique

    The pump functions only after the engine is running and gets the pulse from the crankcase...
    The choke is a separate function..A plate with no hole at all works just like a thumb over the venturi...The hole lets air through....You don't want air, you want fuel from the tank....


    Yup, fuel from the tank.

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    KB1DTB
    AMA11123

    (in reply to Antique)
           Post #: 1435

    RE: mvvs 1.60 gasser - 5/17/2008 4:58:40 PM   
    RysiuM



    Posts: 1400
    Joined: 4/22/2003
    From: Elk Grove, CA, USA
    Status: offline     		I hope Pe will jump and either correct me or explain better.

    We are talking about "pumped" carburetors, not a simple "glow engine" carb. The thumb over the inlet for sucking the fuel from the tank works in glow engines. Just simple action as the engine works as a pump creating a vacuum in the carburetor and therefore it sucks the fuel straight from the fuel tank.

    Walbro is a little more complicated and creating a vacuum in the carb inlet does not suck the fuel from the tank - there is a system of flow and pressure regulators as well as the fuel pump in the way. If you increase the pressure in the glow engine fuel tank, the fuel will flow (overflow) through carburetor. If you increase the pressure in the fuel tank for gas engine you will not increase the fuel flow through the Walbro carburetor - there is a pressure regulator on the way.

    Closing the choke (or finger over the inlet) makes the mixture just richer enough for startup, but will not free-flow the fuel into the engine. In MVVS the standard choke plate works very well for the purpose of starting the engine - as it is.

    The pump works from the pressure pulse from the crankcase. Flipping the engine by hand creates a single pulse, that moves the pump membrane and pushes some fuel. So when you flip the prop and the fuel is in the line, but did not get to the carb yet you should see the fuel move. As soon as it gets to the carburetor, the fuel pressure regulator in the carburetor stops the fuel from moving fast. This is how I understand it supposed to work.



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    Mather Aerospace Modelers, Inc.
    AMA Gold Leader Club, Charter #1243, Sacramento, CA

    (in reply to PlaneKrazee)
           Post #: 1436

    RE: mvvs 1.60 gasser - 5/18/2008 4:44:08 AM   
    PLANE JIM



    Posts: 913
    Joined: 12/22/2002
    From: pinehurst, TX, USA
    Status: online     		I disagree R, When I put my thumb over my carb hole on my walbro carb it gets real wet-real quick, I think there maybe some effect on fuel flow other than shutting the air off to make a rich mixture.

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    (in reply to RysiuM)
           Post #: 1437

    RE: mvvs 1.60 gasser - 5/18/2008 6:43:03 PM   
    pe reivers



    Posts: 2791
    Joined: 1/23/2002
    From: Arcen, , NETHERLANDS
    Status: offline     		soldering the choke hole shut WILL improve initial fuel suction to the point that it will start in three flips. With choke fully closed, the pump will be bypassed and fuel is drawn directly from the tank.
    Just be sure to have ignition on, so the engine will fire when it gets fuel.
    This is a carb issue, and changing the carb will often solve it. Closing the choke hole with the thumb also works, privided the carb (strainer mesh) is clean inside, and idle needle is not too lean.

    _____________________________

    Pe, Dealer for MVVS, MTW and Mejzlik; www.mvvs.nl
    There is sanctuary in analisys.

    (in reply to PLANE JIM)
           Post #: 1438

    RE: mvvs 1.60 gasser - 5/19/2008 7:55:13 AM   
    RysiuM



    Posts: 1400
    Joined: 4/22/2003
    From: Elk Grove, CA, USA
    Status: offline     		Thanks Pe for the input.

    I tested the "finger over the carb" on the bench and indeed the fuel was pulled through the line - like in the old glow engine. So I was wrong. I admit that. However with the engine inverted this is not really safe way to flip the prop, so indeed closing the hole in the choke butterfly should improve the action.

    What I noticed, that as soon as I stopped turning the engine the fuel retracted back to the tank - very fast (about 6 inch/second). It means the pump did not hold. I could see the pump was doing something as every flip the fuel went up the tube about 1/4 inch and immediately returned back to the tank.

    I opened the pump cover and I checked everything for leaks. There were no any. The only thing I did not