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Oliver 77 carburetor

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Warren

06-12-2000 07:55:25




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Help!
My gas Oliver 77 is giving me fits. I recently changed the intake and exhaust manifold and the valve cover. Now, it idles fine, but when I give it a little throttle, it quickly speeds up then slows to the appropriate engine speed. If I try to let it work even a little, the governor keeps kicking in - speeding and slowing rythmically. I have an IT manual for the tractor, but it does not give any information on adjusting the carburetor.
Does anyone have any suggestions about what the idle screw setting should be and what the high speed screw setting should be?
Come to think of it, I am not even sure which screw is which. There is a small slotted screw on the side near the top of the body. There is also a larger knurled brass screw on the back end of the carburetor. It seems that no matter how I adjust them, I don't see much change. The governor keeps kicking in. Since the governor is kicking in, I assume that it is working. I don't really want to mess with the governor if I don't have to.
I don't think I have any intake leaks.
Any suggestions on where to start?

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Delbert

06-13-2000 07:36:09




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 Re: Oliver 77 carburetor in reply to Warren, 06-12-2000 07:55:25  
A lot of good info mentioned. One thing though, inchanging the manifold the distance of the carburator from thegovernor may have changed due to the loosenes of the mounting holes. The length of the rod needs to be checked. To do that put the throttle lever on the steering column in fast position, check rod for binding, loosen jam nut and remove the pin from the rod and adjust the length so the rod fits with a small amount of pressure with the carb shaft in the max open position. One of my Oliver books describes this procedure and it works for all Olivers and some other brands as well. A method I use to adjust the load screw is to open to about 2 1\2 turns, warm the engine to operating temperature, open the throttle, then slowly close the screw till the engine sputters or stalls, quickly open screw 1\2 turn or so, if engine revs up with throttle with out needing the choke it is in the ball park, if engine hesitates or needs the choke open screw 1\4 turn at a time till engine speeds up smoothly. Oliver governors are verry sensitive, I like to adjust the surge screw so the governors bounce once or twice. Another thing I have a Super 55 that would over speed when opening the throttle, I did every thing mentioned here and some. What I found was the cross bar for the fly weights in the governor had broke loose from the shaft, being of the mind it was broke, I could not hurt anything so I aligned it as good as I could and spot welded it. Guess what, it works and I did not need to buy new parts. Hope all this helps. Delbert

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Dick l

06-12-2000 16:04:38




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 Re: Oliver 77 carburetor in reply to Warren, 06-12-2000 07:55:25  

A little bit of information that might help you more understand what your adjustments do. The idle screw is an adjustment for changing the air fuel mixture. Turning the screw in closes off the air and makes the mixture richer. Opening or turning the screw out lets more air in and makes the mixture more lean at.



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Bob M

06-12-2000 15:15:55




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 Re: Oliver 77 carburetor in reply to Warren, 06-12-2000 07:55:25  
Warren - The advice below is all good. But here's one more thing to check:

With the engine stopped and the governor handle set at idle, check to make sure the governor to carb link moves freely - it should almost feel loose. If there is ANY hint of sticking, check for a binding clevis, also for a bent throttle shaft in the carb. Twice I've encountered this problem with 1600/1650's - sticky linkages made the governor snap the throttle open and shut rythmically just as you describe. Once the linkage was freed up the problems disappeared.

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Dennis(WA)

06-12-2000 14:55:58




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 Re: Oliver 77 carburetor in reply to Warren, 06-12-2000 07:55:25  
I have another thought on this. Check you fuel tank for debris. You may have a restriction in the gas flow to the carb. You may be getting enough gas for a good idle, but when you put it under load it is starving for fuel, and the governor is trying to compensate by opening and closing the throttle. Look down in your tank with a flashlight, at the gas outlet, to see if it is clear. Good luck.

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Dick L

06-12-2000 15:19:22




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 Re: Re: Oliver 77 carburetor in reply to Dennis(WA), 06-12-2000 14:55:58  

Dennis, your correct, junk and crud in gas tanks and sediment bowls can give you all kinds of weird problems.



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Dick L

06-12-2000 10:50:35




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 Re: Oliver 77 carburetor in reply to Warren, 06-12-2000 07:55:25  
It sounds as though you have not adjusted the carb yet. If you have not, (don,t!) You will find a cap screw with a jam nut in the govener cover between the radiator a govenor cover. Turn this cap screw in 1/8 of a turn at a time, starting and checking it each time. This screw acts as a damper and should correct your problem. If you have adjusted the carb the sloted knurled screw at the top is the idle screw. You start by turning it in to bottom and backing it out two full turns, start the engine and idle as slow as you can without the engine stoping. Turn the screw in to where the engine slows, then turn it out very slowly as the engine speed up and stop turning out when the engine just starts to slow again. You then set the idle RPM's with the linkage stop screw at the back of the carb. The power setting has to be done under load. If you don't have access to a dyno you will have to hook up to a load and cut and try

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Warren

06-12-2000 12:27:19




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 Re: Re: Oliver 77 carburetor in reply to Dick L, 06-12-2000 10:50:35  
Dick,
Thank you very much for the information. Of course I couldn't have left well enough alone so I did mess with the carb settings. I will follow your instructions since they make perfect sense. I do not have a dyno, but I can hook it to something that requires power. How will I know where to start with the load screw setting and how will I know when to stop, since I would imagine that the governor will kick in when needed.
Why do you think that all this changed because I only changed the manifold? How would that change the governor setting requirements.
Thanks again for the information!

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larry

06-13-2000 05:18:52




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 Re: Re: Re: Oliver 77 carburetor in reply to Warren, 06-12-2000 12:27:19  
If the intake manifold was leaking or bad in some way it will have a great effect on how the adjustments are set. Replaceing with a good one means you have to make changes.



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Dick L

06-12-2000 14:00:13




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 Re: Re: Re: Oliver 77 carburetor in reply to Warren, 06-12-2000 12:27:19  
The adjusting screw for the load setting would start at 2 to 2 1/2 turns out from bottom. I have never had a problem with the govener on a tractor that I use, but have with tractors that I buy and always asumed that some one had been adjusting something that didn't need adjusting. Someone else might be able to give you the reason if you have had the tractor and it just started to surge.



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Dick L

06-12-2000 15:15:52




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 Re: Re: Re: Re: Oliver 77 carburetor in reply to Dick L, 06-12-2000 14:00:13  

I was thinking it but didn't say I would get the carb adjusted before trying to adjust the goverer. I bought an Allis that was surging and after I got the carb. adjusted properly the surging stoped.



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Scott Green

06-13-2000 05:52:53




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 Re: Re: Re: Re: Re: Oliver 77 carburetor in reply to Dick L, 06-12-2000 15:15:52  
Warren , listen to what Dick L. had to say about carb ajustment and the governor bumper screw on the governor houseing. He is on the money. After reading your post , I was going to mention that myself.That was until I come upon Dick's posting.He told you almost word for word what I was going to say.If your governors are surging , it's most likely your bumper screw ajustment.Now it sounds like you have to reajust your carb also. I've had to make governor bumper screw ajustments myself in the past. Scott

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