Strange new behavior of Stromberg carb in ‘71 164. Needle and seat function fine. Float appears ok. Put everything back together and no leaks. After a couple of days (this morning) fuel pours out of the float chamber vent as before. As the engine warmed up, the flow slowed and stopped when the engine was at operating temperature. Any hints or advice. I was at the point of junking it. Not really, but awfully frustrated.

Are you using spring loaded rubber tipped needle & seat?

I would try lifting or lowering the idle speed 50rpm.

It could be something silly like the torsion vibration damper since it's likely to be 45+ years old, it might not work until the old rubber warms up. I'd check the that the timing marks are still accurate too.

The needle and seat are all metal.

Are you still running with the mechanical pump or have you converted to an electric pump?

Thanks for the help and advice. I took the carburetor to a friend from whom I’ve bought parts and had do machine work. He adjusted the float so it would shut the valve at a lower fuel level. It still leaks, but not so much. I’ll try tomorrow to adjust it more. Again, thanks for the help. I hope adjusting fuel level, which fits your ideas, will do it. What a saga. Thanks for the help on the instrument panel, too. All I really needed to do was clean the connections.

If this car in your ownership has run properly and the carb hasn't overflowed/leaked the actual adjustment of the float should be within the range of correct settings. That leaves the possibility of the float sticking somehow, as I mentioned, or maybe the float has sprung a leak. You can usually diagnose the latter by a quick shake but better to submerge it completely in very hot water and see if any bubbles appear. Don't try and repair it just replace.
Needles can and do leak even if they look fine. Again, replace.
Setting the float level to the book is obviously a good idea. If it says to adjust by bending the tab, do it that way, not by bending the whole hinge. The float has to rest at the correct angle.
Both carbs? Possibly just the rear one?

Thanks for the help. Tested float as you suggested. Both parts have small leaks, at least small bubbles, even in lukewarm water. Now to find a source for needle and seat and float.

Do the floats have any fuel sloshing around in them?

Make sure that the float is completely free on its pivot. Should have a little sideways movement on the pin. Just enough so it can't stick.

Hello,

I suspect you still have a float or float valve problem.

The only way fuel comes out of the vent hole is too much fuel in the float bowl or too much fuel pressure.
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Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502
hiperformanceautoservice.com or oldvolvosonly.com