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Is anyone familiar with Carter WD-0 carbs? Mine is making black smoke, I have adjusted the flaot by the book and then lower, still smoking. Idle mix screws are right in too. Any suggestions?
Gary

What's it on? WDO is '30-40s
IF '49, it should be WGD

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The 22nd Series 1949 models still used the WDO carburetor

Yes, it is 1949, 23rd series according to the bodyt plate, and built RHD.

Gary49eight

Remember the guidance from Carter, that is, confirm the tune-up items before the carburetor is condemned. That said, I would first look at the following items:

Fuel shut-off valve (aka needle and seat). Since you indicated iterating the float level I’m sure you are aware of the hardware. However, if the needle and seat are leaking I would also think the engine would stall at idle from ‘flooding’. Excessive fuel pressure is also thrown into this category.

Metering needles not installed correctly. If the needles are not blocking a portion of the main jet area, then the mixture would be ‘wildly rich’. Upon assemble the needles should ‘plunge’ up and down freely in the main jets. Smoothness of the ‘plunging’ also validates the vacuum piston is not binding.

If the vacuum piston is riding high from a poor piston fit in bore, incorrect return spring, or the fundamental adjustment of the ‘finger’ that inhibits the downward stroke as a function of the throttle position . . . any of those will push the mixture rich.

I believe one of those small round gaskets on the aft side of the carburetor housing is dedicated to the vacuum piston. If that is leaking the piston will ride high and push you rich. I believe you will hear a whistling if that gasket is leaking.

To complete the list, but I’ve never encountered this, the main jets may be loose, that is, not tightened in the threaded bore.

I would pull all of the spark plugs and confirm that all of the plugs show a rich condition. If 4 are rich, and the other 4 are OK, then that’s another list of items to check. I would do that before the next carb disassembly.

If you still have the brass tag, let us know the number.

dp

And in conjunction with the leaking needle valve or seat possibility, if you are running an electric fuel pump make sure the output pressure is not too high and pressure is overpowering the float and forcing fuel past the needle valve.

Thank you David and Howard. I do have an elec fuel pump (for starting) as well as the mech pump. I will check all that again. There was no spring under the vacuum piston, but one that is too stiff would make it run rich, correct? No spring would mean the rods are lifted by throttle only, so it still should work.
I did find a bit of muck in the air filter. Is anyone still using the original oil bath filter, and is there a recommended oil?
Gary

Either the shop or owner's manual makes a recommendation for the grade of oil to be used in the oil bath air filter, IIRC SAE 40.

Thanks David and Howard. I checked that again, and I have given up smoking. I am pretty sire it was the air filter too full and had a bit of muck in it. Gaery