The Ford Barn

johnsor · 08-02-2011, 12:32 PM

I rebuilt and installed a Model B carburetor on my Model A. It runs at a higher throttle setting but will not idle. Even then it dies when I retard the spark. Apparently the idle circuit is still plugged or not working. This used B carb must have layed around many years someplace as it was badly rusted and corroded inside. With lots of bead blasting, probeing, and acid cleaning, much gunk came out.

There must be an internal passage still plugged in the idle circuit? Is there anywhere where I can get a carb circuit diagram of the Model B-2 carb? Thanks, John

DavidG · 08-02-2011, 12:58 PM

John,

The 1932 Ford Service Bulletins contain such a diagram. They are available in inexpensive reproduction form.

FlatheadTed · 08-02-2011, 03:37 PM

The throttle plate when closed on the inside should have a hole next to it that is the idle circuit. should have a brass screw into it farther up . follow all these passages and run a thin wire through them.and compressed air

SSsssteamer · 08-03-2011, 01:31 AM

I recently went through this same problem with a couple of B carbs that I rebuilt with China carb kids purchased from Mac's Auto Parts. None of the float bowl Jets were the proper sizes. I re-installed the original Zenith jets and the B carbs now run proper at all speeds without having to adjust anything with the changing rpms on the road. I checked the jet sizes using my oxy/act tip cleaners. A wrong jet size makes a big difference on how well the carb will work.

James D Hudspeth · 03-31-2014, 06:47 AM

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The problem may be within the carb itself. the compensator jet passage has a flow restrictor in the bottom that erodes (rusts) away. If the hole gets too big the idle goes lean. I don't have the exact drill size with me right now but its around a #47 or a bit smaller.

08-02-2011, 12:32 PM	#1
johnsor Senior Member Join Date: May 2010 Location: Spooner, Wisconsin Posts: 242	Model B Carburetor I rebuilt and installed a Model B carburetor on my Model A. It runs at a higher throttle setting but will not idle. Even then it dies when I retard the spark. Apparently the idle circuit is still plugged or not working. This used B carb must have layed around many years someplace as it was badly rusted and corroded inside. With lots of bead blasting, probeing, and acid cleaning, much gunk came out. There must be an internal passage still plugged in the idle circuit? Is there anywhere where I can get a carb circuit diagram of the Model B-2 carb? Thanks, John

08-02-2011, 12:58 PM	#2
DavidG Senior Member Join Date: May 2010 Location: southeastern Michigan Posts: 10,095	Re: Model B Carburetor John, The 1932 Ford Service Bulletins contain such a diagram. They are available in inexpensive reproduction form.

08-02-2011, 03:37 PM	#3
FlatheadTed Senior Member Join Date: May 2010 Location: Auckland Posts: 4,700	Re: Model B Carburetor The throttle plate when closed on the inside should have a hole next to it that is the idle circuit. should have a brass screw into it farther up . follow all these passages and run a thin wire through them.and compressed air __________________ http://www.flatheadted.com Flathead Ted brake Floaters ,

03-31-2014, 06:47 AM	#5
James D Hudspeth Junior Member Join Date: Oct 2010 Posts: 2	Re: Model B Carburetor Sponsored Links (Register now to hide all advertisements) The problem may be within the carb itself. the compensator jet passage has a flow restrictor in the bottom that erodes (rusts) away. If the hole gets too big the idle goes lean. I don't have the exact drill size with me right now but its around a #47 or a bit smaller.

08-03-2011, 01:31 AM	#4
SSsssteamer Senior Member Join Date: Nov 2010 Location: Sedro-Woolley, WA Posts: 1,023	Re: Model B Carburetor I recently went through this same problem with a couple of B carbs that I rebuilt with China carb kids purchased from Mac's Auto Parts. None of the float bowl Jets were the proper sizes. I re-installed the original Zenith jets and the B carbs now run proper at all speeds without having to adjust anything with the changing rpms on the road. I checked the jet sizes using my oxy/act tip cleaners. A wrong jet size makes a big difference on how well the carb will work.