I have just got my 73 2.0 back and running, rebuilt the carbs, new distribtor, points, wirers, ect., but just the other day while trying to tune the carbs I noticed air bubbles cumming up through the clear fuel line that comes through the body of the car and the are bubble are collecting to for one big bubble in the hose just before the carb., any ideas.

IME - they all do that...

if it's objectionable, find an opaque fiilter ...

I've had carbs for years and haven't seen bubbles.
I have clear filter mounted on the side by the battery just after the fuel line comes up from below the engine shelf.

My fuel pump is up front directly under the tank.

Where is your pump mounted?

When filling the tank, the fuel is aerated. If your tank and lines have been empty for a period of time, those bubbles can adhere to lines (cohesive) and get washed off after a time of flow. Fill a glass of water and watch.

Otherwise you could be sucking some air on the suction side of your pump at the pump fitting, but......,

i have most observed this phenomonon on a succession of T-I and T-III VW engines and the 356, where the mechanical fuel pump is bolted to the crankcase and actuated by a pushrod off the distributor drive gear. i've seen it to a lesser extent in the 914.6 where the pump was still located in its original place, under the tin. IIRC (been a while...) the hot air from the 914.6 heat exchanger dump valve isn't quite as badly located as it was with the 914.4 ...

after that cama a succession of fuel-injected cars with opaque lines...

if it's really hot, you could be seeing a bit of pre-vapor lock.

it would be prudent, of course, to check for leaks, because if air is getting in, fuel is probably getting out. i think you're just seeing the result of entrained air due to sloshing, however...

thanks for the early morning chuckle Rich

that was GUD

.........b

I get air bubbles stuck to my beer glass when I pour a Guiness. Hmm but that is a good thing. Same principle????? Aerated fuel when filling. I'll buy that.

If that offends you get an opaque glass

MMMM Guiness

Toothsheaf Stout - bigger bottle - more bang for the buck