Fuel line air bubbles

[Mustlust]

Just replaced points with an accuspark elec unit. That all seems to be fine but just can’t get a smooth idle. Plugs are a little sooty, so will thin the mixture a little and see how things turn out.
I have noticed air bubbles in the clear fuel line that runs from the pump to the carby. I’m guessing there must be a little seal not doing it’s job in the pump, although having overhauled it recently, I’d be surprised.

Would are bubbles into the carby impact on idle??????

[Blknight.aus]

not really,

the bubbles will separate out in the bowl and the bowl is vented to the body so the fuel hitting the jets should be straight liquid.

if they were getting into the jets you'd be running lean which would give the opposite results to the carbon fouling on the plugs you describe.

[russellrovers]

Just replaced points with an accuspark elec unit. That all seems to be fine but just can’t get a smooth idle. Plugs are a little sooty, so will thin the mixture a little and see how things turn out.
I have noticed air bubbles in the clear fuel line that runs from the pump to the carby. I’m guessing there must be a little seal not doing it’s job in the pump, although having overhauled it recently, I’d be surprised.
can pull in on the fu
Would are bubbles into the carby impact on idle?????? can pull aair in on the fuel bowl seals

[JDNSW]

Bubbles will not affect the idle. They indicate a leak somewhere on the suction side of the pump. Likely places are all connections, the gasket on the sediment bowl assuming you have one, and rust pin holes in the pickup pipe in the tank. Anywhere on the pressure side of the pump, including the pump diaphragm will show as a fuel leak.

Leaks on the suction side may show as a slight fuel leak, but may not do so if they are slight, and certainly will not be seen if they are on the pickup pipe inside the tank.

[Bundy]

What carby are you running? It may be throttle plate spindle/carby body wear allowing air to get sucked into the engine some times and not others. Put some thick grease around the area on both sides and see if you can adjust to get a smooth idle. It may be set rich to compensate.