Car has been running rough lately so I decided to check a few things. First my fuel filter in carb was clogged with lots of crap from the tank. Car had been sitting a couple years so I assume there's some trash in the tank. Replaced in carb filter with an inline one I can see through and cleaned out inlet. Was still running rough so I tore it apart again yesterday and the carb had a far amount of crap in it so cleaned out everything and checked all vitals, looked good so back on the car.
Initially it started and ran fine but then started to get rough again with white smoke coming from tailpipes with a heavy gas smell. I tried adjust fuel mixture screws but they didn't do much of anything. In fact I had them fully seated and the car still ran but very rough. Once I turned car off in about 10-20 seconds fuel starts coming out of the throttle shafts and onto the intake.
My thoughts: 1) bad float not shutting off needle and seat 2) bad fuel pump giving too much pressure.

Anyone have any other ideas or suggestions?

Thanks,
George

 

White smoke can be due to transmission fluid getting into the combustion chamber through a defective vacuum modulator on the transmission. Have you ever replaced the modulator?

Of course, white smoke can also be due to radiator fluid getting into the engine through a leaking head gasket or cracked block. Let's hope it's not one of these. A vacuum modulator is a $20 fix.

Both of your ideas about the carb float and the fuel pump as possible sources of the problem sound reasonable, too.

 

Turns out the whole problem was the staked in brass plug that was to the right of the needle and seat inside the float bowl. I guess cleaning it after 45 years cause the plug to get loose somehow. There was only two ways for fuel to enter that bowl and that was from the needle and seat or that plug. I JB Welded the brass plug in place and now it runs like a dream. I throw this out there for anyone else who might have a similar problem.

Thanks,
George