Farmall H engine races after carb rebuild

[JimTheHut]

I cleaned out my governor of all the sludge. Did not change any settings on it. I then rebuilt the carb because it was really dirty. It is a 1941 that had sat for many years. It was running very good before I did all of this. Now after the rebuild it races and then dies. I have verified that the governor tab is in the carb as it should be. It opens and closes. I have the idle stop set per specs. The governor as acting as it should. I did not verify that the pin on the top moves freely at wide open throttle. I have attached pictures of the throttle and governor at idle and wot. Thanks in advance for your help!

 

[used red MN]

Taking into account that you are sure the governor shaft in the aluminum tube has its tang centered in the “fat vee” of the throttling shaft I will proceed as follows. Hard to see in that photo but It doesn’t look to me like the throttle plate is closing properly. Pull the carb back off, hold the throttle plate closed it should basically allow no light to be seen around the outer edge. If it does you need to reposition it. Loosen the screws on the plate and bring them down a little short of snug so the plate can move under the heads. Then hold some tension against the shaft to close the plate. Lightly tap the throttle plate several times with your screwdriver blade this will center the plate in the carb throat. With continued tension on the shaft tighten the plate screws. Should be good to go now. Not knowing what the manual says that your following to initially set the idle stop screw I would just back it away from the “fat V” and adjust it as needed to provide the proper idle speed when the tractor is running. If you are working off some odd directions that say there is some preset on the idle stop backing that out before you pull the carb would be a good thing to see if that is the trouble. Also get a good light and use your patience when realigning the tab in the fat V when reinstalling the carb.

 

[JimTheHut]

Thanks for the advice! I will do that tomorrow and see what happens! Thanks!

 

[used red MN]

Taking into account that you are sure the governor shaft in the aluminum tube has its tang centered in the “fat vee” of the throttling shaft I will proceed as follows. Hard to see in that photo but It doesn’t look to me like the throttle plate is closing properly. Pull the carb back off, hold the throttle plate closed it should basically allow no light to be seen around the outer edge. If it does you need to reposition it. Loosen the screws on the plate and bring them down a little short of snug so the plate can move under the heads. Then hold some tension against the shaft to close the plate. Lightly tap the throttle plate several times with your screwdriver blade this will center the plate in the carb throat. With continued tension on the shaft tighten the plate screws. Should be good to go now. Not knowing what the manual says that your following to initially set the idle stop screw I would just back it away from the “fat V” and adjust it as needed to provide the proper idle speed when the tractor is running. If you are working off some odd directions that say there is some preset on the idle stop backing that out before you pull the carb would be a good thing to see if that is the trouble. Also get a good light and use your patience when realigning the tab in the fat V when reinstalling the carb.

On second thought if you didn’t do this you should disconnect the throttle control from the governor either on the lever by the block behind the governor or up by the bell crank besides the valve cover just to make sure that this linkage is not the reason the governor is not signaling idle. Also, if that is not the problem you can try holding the governor controls above the governor towards idle under the slanted cover with the breather tube. This would help confirm the problem is in the mispositioned throttle plate.

 

[JimTheHut]

Ok, thanks

 

[Brownie450]

Had trouble like this with our SMTA. The mechanic in town
got the throttle plate in upside down & not centered when
he did the carb. Engine wouldn't idle down. I took the carb
apart & got everything squared around---working well now.
Red is right on with his info.
Jim

 

[JimTheHut]

I got it to idle. I did check the throttle plate and it was in correctly. I ended up just barely opening the throttle stop and it idled. I then opened it up a bit at a time until it was where I wanted it. So the tractor is running great but I have a new issue.....When I shut the tractor off, it drips gas out of the drain hole. I have read on some forums that this is normal on these tractors. However, it did not do this before I rebuilt the carb. It does not do it if I turn the fuel on and let it sit or while the tractor is running. I did adjust the level of the float when i had it apart because it was not per the specs. I increased the height from where it was. Is the float level causing this or something else? Thanks!

 

[Fritz Maurer]

Before you take the carb apart, make sure the sediment bowl is clean , no rubbish in the tank and remove the fuel line from the carb and turn the gas on. Let the gas flow out at full volume for a few seconds and shut it off.

Remove any adapters and try to get as close to the needle/seat assembly as you can. Spray some brake cleaner in there in hopes of flushing out any foreign material that may be too large to pass through the seat into the float chamber.

The reason for running the gas out the open line is for the high velocity of the fuel flow will flush out any loose material that would otherwise end up in your carb. This can happen on a fresh rebuild when the fuel is at high speed filling a dry chamber picks up dirt that ordinarily will just stay in a little corner someplace.

If all of the above fails you will have to open the carb.

 

[JimTheHut]

I have had that carb off and apart at least 6 times in the last couple of days. There is no dirt or anything in it, I am pretty sure of that. I just got done reading that since the engine makes some revolutions when it is turned off, it is still sucking fuel up at of the carb. Since it can not ignite, it falls back down to the bottom of the carb and out the drain. They said they just turn the fuel off and let it run itself out of gas, then no drips. I will see if this happens on mine. Thanks!

 

[Fritz Maurer]

There is not enough vapor to condense and drip out the hole. The drip is coming from the fuel level in the chamber at or above, for whatever reason, the height of the end of the main nozzle . The float needle is not closing completely. Or the gasket under the seat has been omitted, causing both a leak and an elevated float setting.

Also, while it is true that the engine continues to vaporize fuel while it is coasting, most of it is blown out the exhaust.

 

[used red MN]

Float Valve Coining Tool, I didn’t know about these until I read the linked post. I never investigated them or used one but this guy seems to think they are the cats meow. He must be able to work some kind of magic on these old carbs for what he charges to redo them. If I came across a carb with a problematic flooding or leaking while setting trouble I would probably look into one of them.
Recent thread referenced reply 10.

 

[JimTheHut]

Well it appears to fixed for now. I found that I had not squeezed the metal that the float pin goes through enough. I always error on the side of not putting too much pressure on anything. The pin kept walking out of it which caused the float to partially come off. I had a real gusher yesterday. So I took the bottom half of the carb off. I made sure the float was not bent to one side. I shot carb cleaner up through the seat to make sure it was clear.. I made sure that the pin was good and tight so that it will not work itself out. It now does not leak when I shut the engine off. Thanks for all of the help!

 

[JimTheHut]

Well the leak is back. It does not leak with the engine off but fuel turned on. Does not leak when tractor is running. But the drip is back after I shut it off. I will repeat all the recommendations above. Never once dripped before the carb rebuild....Guess if it is not broke don't fix it...lol

 

[used red MN]

It does not leak with the engine off but fuel turned on.

If you turn the gas on and do not start the engine and the carb does not drip then there is NOTHING WRONG with your carburetor. The dripping is from gas that has collected in the carb throat and the vertical section of the manifold while it is running. Then when you shut it off gravity pulls it down and it collects in the bottom of the carb air way. Apparently your drain or vent whatever it is called was plugged before you rebuilt the carb and the gas just stayed in there until it evaporated. How long are you running the tractor? If not long enough to warm the upper intake up say a half hour the dripping will be more prevalent.

 

[JimTheHut]

If you turn the gas on and do not start the engine and the carb does not drip then there is NOTHING WRONG with your carburetor. The dripping is from gas that has collected in the carb throat and the vertical section of the manifold while it is running. Then when you shut it off gravity pulls it down and it collects in the bottom of the carb air way. Apparently your drain or vent whatever it is called was plugged before you rebuilt the carb and the gas just stayed in there until it evaporated. How long are you running the tractor? If not long enough to warm the upper intake up say a half hour the dripping will be more prevalent.

I am not running it very long when this is happening. I have not tried it after I have run it for a long time. I will do that. I had read past posts that said the very same thing that you said. There has been some disagreement on this tread about this. Thanks for your input! I appreciate all the responses!

 

[JimTheHut]

I ran the tractor today. It did not leak when I turned the fuel on. I ran it up and down my neighbors long driveway in road gear and got it nice and warmed up. I parked it and then turned it off. I did not get any fuel dripping out of the drain. Thanks!