1950 "A" questions
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    Wink 1950 "A" questions

    Hey everyone!

    My Dad and I recently picked up a 1950 A propane version that had been sitting in someone's yard as an ornament for years. After completely tearing it apart and rebuilding it we decided to switch it back to gasoline. The carburetor that was on the tractor was a gasoline carb that had been converted to work with propane so we just switched it back to run on gasoline. (replaced the tank and sheet metal of course to the original gasoline version's look). The tractor ran fine for a little bit, even though it never sounded perfect. As we were driving it one time the pin on the carb that prevents the throttle butterfly from closing too far and thereby reopening broke and so when the governor tried pushing the throttle to idle, it overturned the plate and ended up revving the engine very high. We fixed the little pin so that this cannot happen again, however now we cannot get the tractor to run properly. I'm thinking it is a carb issue but since I don't know enough about these tractors I was hoping someone could give me some useful input. It also seems to only want to run when it is its mixture set very rich. The Manual we have says that the adjustment is 1.25 turns out on both adjustment screws however this one only wants to stay idling at about 3.5 turns out. I live at a high elevation (4000 ft.) so it should even be leaned out more not richened.

    Any advice would be greatly appreciated!!!
    Thanks!!!

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    Captain Hook Kennyd's Avatar
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    That's a great looking tractor! Hopefully someone can help you soon.
    Kenny

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    green and red man's Avatar
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    I'm still learning about two cylinders myself. My question might be like trying to tinkle and aim in the dark, but did you reuse the old pistons? Reason I ask, is that was the first thing that came to mind.

    I bought a model 70 that was converted to propane and am still working on getting it going. It's the one in my avatar. The motor was seized when I got it,but was just sitting in a barn for 20 years unused. I'm wondering just what all was swapped on it.


    But, on the other hand it almost sounds like something on yours is obstructing an area of the carb.




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    Quote Originally Posted by green and red man View Post
    but did you reuse the old pistons?
    Yes, we reused the old pistons. this one was sitting in a barn too and was seized too. Cylinder 1 was rusted because it sat with a valve open. we were able to loosen up the piston and hone the cylinder really well and luckily were able to save it. We have about 100psi of compression in both cylinders so thats fine. ours didn't even have a real propane carb, it looked more like a gasoline carb was converted to propane because it still had the float on it. We were able to convert it back to gasoline and it ran alright on it for a couple of months. The intake/exhaust manifold says LP GAS on the top of it but thats the only difference we can see. I assumed it was an obstruction in the carb too but even with a different carb we can't get it running right.

    Another thing I noticed was that right where the carb and intake meet, when it is running there is condensation on the outside of the intake manifold. I have never seen this on a gasoline-powered vehicle and I can't figure out what it could be. It also makes no sense that the condensation appears there instead of elsewhere by the carb.

    Thanks

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    Keeper of the GTT Cookies dieselshadow's Avatar
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    Thumbs up Welcome to GTT!

    Quote Originally Posted by neattouch648 View Post
    Another thing I noticed was that right where the carb and intake meet, when it is running there is condensation on the outside of the intake manifold. I have never seen this on a gasoline-powered vehicle and I can't figure out what it could be. It also makes no sense that the condensation appears there instead of elsewhere by the carb.
    That condensation is caused by the cooling effect that evaporating gasoline downstream of the carb. Most engines the intake manifold has enough heat in it from the engine that it wouldn't be cool enough for moisture to condense on it.

    You stated that you have 100 psi compression. Is that after the over-speed incident? If you have (or have access to) a cylinder leak down tester, you could perform a much more informative test. It'll tell you if you have any mechanical issues within either cylinder. The head and valve train on these twins are very robust, but I think the possibility of a bent valve exists. Can you tell if it's running on both cylinders? Disconnect a plug before starting it to verify. The other possibility I was thinking of was the magneto/ignition system. Not sure what you have due to so many being upgraded. You'll want to verify timing and the integrity of the ignition system. Some of these won't stand up to over revving very well.
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    Quote Originally Posted by dieselshadow View Post
    You stated that you have 100 psi compression. Is that after the over-speed incident? If you have (or have access to) a cylinder leak down tester, you could perform a much more informative test. It'll tell you if you have any mechanical issues within either cylinder. The head and valve train on these twins are very robust, but I think the possibility of a bent valve exists. Can you tell if it's running on both cylinders? Disconnect a plug before starting it to verify. The other possibility I was thinking of was the magneto/ignition system. Not sure what you have due to so many being upgraded. You'll want to verify timing and the integrity of the ignition system. Some of these won't stand up to over revving very well.

    The 100 psi compression is after the over-speed incident, we checked that. As far as I can tell it is firing on both cylinders but I will check it to verify. I don't have a cylinder leak down tester but I can see if I can get my hands on one.

    We assumed it could be the magneto/ignition system too so we verified spark,checked the timing and all of that seems to be in order. We have a strong spark and its still sparking at the right time. I have the magneto turned all the way counter-clockwise as this is where it runs best...I have no more room for adjustment which I think is a bit odd but it isn't the biggest problem right now. I'm really leaning into it being a carburetor issue.

    The fact that the manifold says "LP GAS" on it can't have any negative impacts on the operation of the motor on regular gasoline can it?

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    Keeper of the GTT Cookies dieselshadow's Avatar
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    Does your magneto have an impulse coupling? It's a device that springs the magneto forward during slow RPMs during starting to provide a spark. Magnetos don't perform very well at low RPMs without one. If has malfunctioned, it can cause many issues like the ones you are experiencing. The lack of adjustment left in the timing is a red flag.
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    Quote Originally Posted by Gizmo2 View Post
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    green and red man's Avatar
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    When I first read about the engine revving up, I did picture the possibility of a bent valve. It's just not always easy to diagnose an engine problem without having the luxury of seeing and checking things in person. A friend of mine has one like yours, but he had a totally different problem. He couldn't get fuel to flow.

    Hope you locate the problem soon and without having to spend much $$$$ to fix it.




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    Keeper of the GTT Cookies dieselshadow's Avatar
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    Quote Originally Posted by green and red man View Post
    It's just not always easy to diagnose an engine problem without having the luxury of seeing and checking things in person.
    Well said. It can make one hesitant to answer a question here on the forum. People just have to remember we're all here to help each other and have some fun doing it.
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    Quote Originally Posted by Gizmo2 View Post
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    Quote Originally Posted by neattouch648 View Post
    The 100 psi compression is after the over-speed incident, we checked that. As far as I can tell it is firing on both cylinders but I will check it to verify. I don't have a cylinder leak down tester but I can see if I can get my hands on one.

    We assumed it could be the magneto/ignition system too so we verified spark,checked the timing and all of that seems to be in order. We have a strong spark and its still sparking at the right time. I have the magneto turned all the way counter-clockwise as this is where it runs best...I have no more room for adjustment which I think is a bit odd but it isn't the biggest problem right now. I'm really leaning into it being a carburetor issue.

    The fact that the manifold says "LP GAS" on it can't have any negative impacts on the operation of the motor on regular gasoline can it?
    IMHO, Yes, it could have some negative impact. What I do not know.



    Brian

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