| Carter B&B, BBR Carburetor Problems & Solutions Below you will find questions that users have asked about the Carter 1 barrel carburetor. The questions are followed by our best guess answer. We say best guess, because we don’t have the carburetor in front of us and users often leave out important information. | |
| Engine Only Runs When Choked I bought a rebuild kit from you almost a month ago. after rebuilding my Carburetor i can only get the engine to run with the carburetor on full choke. I have tried adjusting the idle set screw, but it does not make a noticeable difference. I watched your video on BBR carbs and followed the instructions carefully. What can i check or do to make it work again? This is an indication of one of two things. 1 – There is too much air, possibly caused by a vacuum leak. Using a spray carburetor cleaner (be sure you get the straw that connects to the spray nozzle), spray around the throttle body, both where it mounts and where the throttle body connects to the float bowl. If the RPM changes, then you found a vacuum leak. Check other possible connections for a vacuum leak. The intake manifold is one of these. If the problem is new since you did the rebuild, then you could probably concentrate on the carburetor. Most of the kits have multiple throttle body gaskets and it would be easy to install the wrong gasket. This is a common mistake I have made more than once. Carefully inspect to make sure air isn’t being allowed to enter the carburetor at that point. 2 – There isn’t enough fuel. Recheck the float level. Make sure the needle isn’t sticking closed. Cleaning the viton tip with mineral spirits can help with this. Poor fuel pump pressure could also be the cause. Test the pressure and compare with what is printed in your engine manual. Around 4 lbs. Look for any restrictions in the fuel line. Where there is rubber line, replace with high quality fuel injection hose. Ethanol will eat the inside of any rubber line. Did you blow through all of the passages. Ethanol leaves residue behind that cleaners can’t get out. Gas Leaks Out Throttle Shaft This situation probably indicates that the carburetor is flooding (too much fuel). Excess gas runs down the carburetor throat, hits the throttle valve and runs out the throttle shaft. This does not necessarily indicate that the throttle shaft needs to be bushed. It does indicate that the carburetor is putting out too much gas. Probably dirty and needs cleaning. Can I get main jets? Main jets are no longer being produced that we know of. Your solution to different jet sizes are to drill the existing hole to a larger size, or if you need to reduce the size solder the hole shut and drill out to a smaller size. Not the perfect solution, but does work. Excessive Fuel in the Bore You are probably flooding (getting too much fuel in the bowl).Test the fuel pump to be sure it isn’t putting out too much pressure. Check your motors manual for the specification, but probably around 4 lbs. Make sure the needle & seat has the gasket installed and that it isn’t damaged in some way. Make sure the old needle & seat gasket is removed. Any problem with the gasket would allow fuel to flow around the seat. Test the brass float – heat up water and immerse the float. Any bubbles indicates a leak. Make sure the float isn’t sticking when moving it up and down. A worn float pin would do this. The needle may have been damaged when installing. They are easily damaged. With the float up and the needle closed see if you can blow through the needle & seat. Look at the needle to see if there are any marks on the needle. |
Throttle Valve Is 1/2 Open
That is correct: without an external throttle return spring the throttle plate stands 1/2 of the way open. This was done on many Carter carbs (and some Strombergs) so that the accelerator pump was constantly “pre-loaded” no matter how much wear might be in the linkage. I experienced the downside of that engineering for myself in 1977 when the throttle return spring broke on my ’67 Plymouth and the engine immediately accelerated to half-throttle. Luckily, I new exactly what to do (thanks to good prior instruction) and an accident was avoided: pop it into neutral, shut off the engine and coast to the side of the road.
Hesitation or Bog
Your engine hesitation when stepping on the gas can be caused by a couple of things. One would be the distributor advance not working properly.
The other might be the accelerator pump circuit.
The Carter B&B uses a leather cup on the accelerator pump. Be sure it didn’t dry out and curl up. With the engine off look down the carburetor bore. Pump the gas. You should see a good stream of gas come out of the main discharge. No squirt? Something is plugged. The main discharge can get plugged up because they seldom get cleaned. Look for the aluminum plug on the side of the carburetor just below where the top and main body meet. With the top off look down at the main discharge. Remove the plug and take the main discharge jet out. The jet comes out with a screw driver and they break easily, so if it doesn’t come out easily, then leave it in and clean it thoroughly. From there clean and blow out all of the passages.
Some of the B&B have an intake check ball on the bottom of the fuel bowl. Take the plug out and make sure the check ball is clean and loose. Also can you blow air through to the pump well? This is how the fuel gets into the pump well.
Fuel Bowl Empties Overnight
Some possibilities: Fuel is percolating – Engine gets hot, then you shut it off. Gas boils over into the engine. A good indication would be fuel coming out the throttle shaft when turning off the engine. See Percolation. Fuel evaporates – Today’s fuel evaporates and a much greater rate than it did pre non lead. Try other grades of fuel. If possible, use non ethanol gas. When starting this type of problem, don’t pump the gas pedal. If the fuel bowl is empty then pumping the throttle prolongs the problem. Crank a few seconds to let the bowl fill, then pump once. After turning the engine off look down the carburetor to see if gas is still running into the engine. If it is, and it shouldn’t be, then the check ball in main discharge may be leaking. Gas cap is non vented and should be vented type, bowl vent should not be closed off. Gas leaking out the bottom of the fuel bowl. This isn’t hard to figure out. Place paper under the carburetor full of fuel overnight.
