farmall B carb adjustment. (2024)

B runs good. has a slight flutter at WOT. if i adjust the screw will that help to lean or richen it up? I rebuilt the carb last fall. new float and cleaned it all and passages.

Pulled plugs. #1 doesn't look right. put new plugs in. runs will pop pop once in a while. if i pull choke half closed it runs fine. My carb adjusted wrong??

Does your carb have the adjustment screw that sits low on the bowl or is your the type that has a plug in that area?? If the adjustment your messing with sits high on the carb just under the mount area that will not help you any that is the idle adjustment screw. If yours has that plug it means you got some dirt/rust clogging up the main jet and you need to clean the carb and maybe even put a kit in it

Unless you have it set up like a distillate/kero carb there is no main adjustment. Only idle speed and idle mixture. If it is set up for distillate, to adjust at WOT you turn the screw in (lean) until it sputters and then out until smooth. It can be opened slightly more if it does not seem to have enough power, but should be as lean as possible and still function properly.

You are running lean under load. Question, do you have a fuel filter in the fuel line? If yes get rid of it you do not need it and the carburetor will not function properly with it in place. It can make the carburetor run lean under load. Make sure the fuel line is clear as well as the screen on the inlet to the carburetor. Drain both the carburetor bowl and the glass bowl under the fuel tank. If the tractor has not been run much lately, you need to run it. If the fuel is old you might have to drain the carburetor bowl several times until you run about one or two tanks of gasoline through the engine. It is a routine we went through every spring with our 200 back in the day. If this does not work you may have a vacuum leak in the intake manifold.

Does your carb have the adjustable jet in the lower bowl facing the generator if not there are no adjustments to solve the problem other two screws are for idle mixture and idle speed screw on the main shaft next to the block.

I think its got a valve problem. no signs of an intake gasket leak when using propane or carb cleaner. i just got the choke half shut and runs like a top. good enough for mowing. thanks guys.

Ive been using the Fram see-thru in-line filters for yrs and they do their job excellent as they catch dirt the screen in the sediment bowl doesent catch they have all the flow needed to operate the engine when the flow stops or slows down they are dirty because they are doing their job. Sometimes we just have a gastank that needs a little more cleaning.