Carter BB-1 Updraft Carburetor

Question: The carburetor kit has two check balls. Where do they go?

Two check balls come in the kit, but only one is typically used. It is the ball in the power valve which gets replaced, and it is best removed by inserting a punch or other pin through the holes in the valve body while unscrewing the jet from the bottom. IMPORTANT: a tiny spring goes in between the jet and the ball; don’t lose it upon disassembly!
The other two balls in those jets/check valves in the bottom of the bowl are captive and cannot be removed from the assembly. They must, however, be loose or (at the very least) the accel pump won’t work. And it is still a good idea to remove those valve assemblies to clean them and beneath them — if they will come out.
I asked Jeff about making a push up rod for the Carter updraft BB-1. They are not available anymore and the though was that perhaps we could make it ourselves.Here is his answer.
Sorry, no, I don’t have the spec on that rod. The diameter is either 3/32″ or 1/8″ IIRC, and it should be tapered somewhat on the end which goes into the power valve in the bowl bottom.
To determine the right length, take a piece of brass rod and push it down into the power valve to compress the check ball spring. With the spring compressed, mark the rod at the exact point where it is level with the top of the bowl casting gasket surface. Now invert the bowl lid and place the rod into the vacuum piston hole but DO NOT COMPRESS THE PISTON. Mark the exact length from the piston to the bowl lid gasket surface. Measure the two marks on the rod and add the two figures plus 1/32″ for the gasket thickness and you should have the length to which to cut the rod.

Recent Posts

Choke Types

We have 4 different types of chokes, Intregal, Divorced, Electric & Electric Conversion.

Intregal Choke

Integral ChokeThe integral choke is mounted on the carburetor, either near the top, or near the bottom. The illustration shows the choke mounted on the top of the carburetor. The thermostat is heated by a heat tube that runs down to the exhaust manifold. The heat tubes heats up the thermostat and moves the choke valve to the open position. A vacuum passage in the carburetor feeds up to the choke housing and helps pull in the heat from the heat tube. Some of these chokes will also have a hot water jacket running through, or on the thermostat to facilitate heating.

Divorced Choke

Divorced ChokeThe divorced choke typs has the thermostat mounted in the intake manifold instead of on the carburetor. In this illustration, the arrow points to the thermostat which is covered by a metal shield. A rod connects the thermostat to the choke lever, which controls the choke valve to be opened, or closed. As the intake manifold heats up, the thermostat mounted, expands, opening the choke valve.


Electric Choke


Electric ChokeThis is a typical electric choke mounted on the carburetor, which is integral. In this case there is one wire on the choke thermostat. This is the 12v source, which all electric chokes use. The thermostat is grounded via the carburetor itself. Some electric chokes will have a 2nd wire (ground wire), which is connected back to the carburetor. When the key is on the thermostat is heated up, opening the choke valve.

Electric Choke Conversion


Electric Choke ConversionThis is a typical electric choke conversion kit. This is used to convert an integral, or a divorced choke to an electric choke. These choke kits come with a temperature sensor that bolts on to the intake manifold, which provides more accurate choke control than with an electric choke without the gauge. The electric choke conversion kit is not used for a manual choke conversion. The choke housing must be in place in order for it to work.
This choke installs in 20 minutes or less with no special
tools. Remove the old choke thermostat and replace with this choke conversion kit.
Attach the temperature sensor under an existing engine bolt.
Wire the positive wire into the vehicles electrical system. Ground the choke to the carburetor.
Complete instructions are provided for each application.


  1. Bobs Carburetor Shop Leave a reply
  2. Carburetor Percolation 1 Reply
  3. How a Choke Works Integral Type 5 Replies
  4. Motorcraft 4300 Power Piston 1 Reply
  5. Gas Tank Fuel Gauge Leave a reply
  6. Tips on Removing Frozen Parts Leave a reply
  7. Stromberg WW Worn Throttle Shafts Leave a reply
  8. Late to the Electric Party Leave a reply
  9. O2 Sensors – Engine Performance from a Capsule Leave a reply