Vanguard Engine questions

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Thread: Vanguard Engine questions

  1. #1

    Vanguard Engine questions

    I have a early 1990's Vanguard with the 16hp v twin. Its new to me and I am trying to sort it out.

    For some yet unknown reason the governor springs were hooked up all backwards. The governor spring held the throttle closed?? So it did not balance the governor and relied entirely on throttle setting. I suspect the idle spring is stock, but the governor spring I do not not know.

    Anyway as I work through trying to tune I have some questions.

    1. I am trying to set the no load (in neutral) idle at about 1075 rpm. Just cause that sounds right to me. What do others suggest?

    2. I am trying to set the governor no load to be about 3600 rpm at full throttle. At full throttle that is about 3300 at speed in gear. Should I set it for 3600 at speed in gear - that make more sense to me?

    3. When suddenly throttling up it will surge 4 or 5 times before settling down at full throttle. Since the governor was all messed up, I feel comfortable its not the carb. Plus I have removed and cleaned pilot and main jets (not whole carb though) Any thoughts - I assume governor springs etc but can find no specs.

    Now it remains twitchy with RPMs not staying stable after throttle up. It returns to 1100 at one time the 1300 the next. I assume that is some sticky linkages - plus they are a little sloppy.

    Experience to me would say carb, but after messing with it, I am leaning to governor issue.

    Any thoughts ??

  2. #2
    Join Date
    Nov 2020
    Location
    Southwestern Ont Can about 5 miles from Lake Huron just north of the town of Goderich.
    Posts
    181
    When the engine is not running the governor should hold the throttle wide open. When the engine fires the governor shuts the throttle to the setting of the idle screw. You can set the high and low rpm by bending the tabs that springs are attached to increasing or decreasing the pressure on the springs. Sound like you are aware of that, if not there are some very good tutorials on utube. As far as the surging, I would personally lean toward the carb. Most of the time, not all the time, but most surging is caused by dirt in the carb some where. There also could be some moisture, a.k.a. water in the fuel that may not be detected. The small engines are a pain in the butt when not running right and you can't just put your finger on it. My 23 Vanguard was not running like I like it to be, so I adjusted the carb, checked for moisture, changed the plugs. Finally I did a spark test and found that one coil was misfiring at an idle and also at higher rpm. Not all the time but every once in a while. Installed a new coil and cleaned up the running problem. Just because it seems like a fuel problem doesn't necessarily mean it is. Just an after thought your carburator might just be plain worn out depending on the hrs on it.

  3. #3
    Hang on. "When the engine is not running the governor should be holding the throttle wide open"

    I am new to these machines but how is that? Is not the governor arm position determined by the hand throttle. The governor spring and the governor 'piston' then equalize at the chosen RPM of the driver's throttle position until a load is encountered when the governor then automatically opens the carb to compensate???
    I would think with engine off the governor should return to rest as the hand throttle is released which means the call for less RPM overrides the governor and brings it down??

    Having the governor arm open the throttle wide open with engine off confuses me.

    My world is upside down at the moment?

  4. #4
    Join Date
    Nov 2020
    Location
    Southwestern Ont Can about 5 miles from Lake Huron just north of the town of Goderich.
    Posts
    181
    Check it out in a briggs service manual, set up the governor the way the book says to. I just went and looked at a 16 vanguard horizontal shaft on a rider. Throttle off, engine off. Throttle position wide open. Once the engine fires the inner governor mechanism puts pressure on the arm pushing the throttle closed to idle position. When you open the throttle the springs you mentioned pull on the arm opening the throttle to the governed position. That is when you take your special tool and adjust your spring tension. I am pretty sure the small spring sets your idle and the fat one the high rpm. On something like a lawnmower you generally run wide open and when the mower hits a heavy patch, you hear the rpm drop and the governor takes over because the throttle position is still wide open but the inner mechanism is not pushing as hard on the arm because the rpm dropped thereby opening the throttle to maintain the governed rpm until the heavy patch is done and then as the rpm pick up the mechanism let's the governor return to the governed position. So when the engine is off there is no pressure on the arm the governor opens the throttle wide open.

  5. #5
    Join Date
    Nov 2021
    Location
    Western Ky
    Posts
    21
    The governor with the engine off has the throttle in the WOT (wide open throttle) position. The throttle does not control the carb or connect to it the carb in any way it only controls the governor which controls the carb throttle plate. This is true for ANY carb engine that has a governor.

    There are plenty of Briggs manuals online, I recommend you take some time to read up on the function and operation of the governor before tinkering or adjusting anything.

  6. #6
    Thanks Laird and JWW.
    I have done my share of engine work in the past.

    My throttle is only connected to the circular rotating throttle lever. As you mention it is not connected to the carb but only to the governor by the idle spring - as is normal. Notwithstanding a tang on the circular throttle control lever, on my machine, limits movement of the governor as I describe in my first post. That tang limits the governor to only move and open the carb plate to the limit set by the circular throttle position.

    It sounds like my engine set up is different. I will continue my research.

  7. #7
    So the tang I am referring to is called by B&S as a 'Throttle Restrictor Tang' .

  8. #8
    So for those who like closure....

    The shaft on which the circular throttle lever rotates was worn a small amount but enough to affect the governor. I machined a new one and installed. All is well.

  9. #9
    Join Date
    Nov 2020
    Location
    Southwestern Ont Can about 5 miles from Lake Huron just north of the town of Goderich.
    Posts
    181
    Interesting. Thanks for the update. May help someone else out.

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