Have 72 BB 454 w/ 750 edelbrock carb & glass filter houseing. Have noticed that after shutting down the filter seems to empty out back in the direction of the tank, even with full tank. I know the line will gravity towards the carb as I have had the line open and it did. Was thinking, is it possoble to have a plugged return line to tank and be pulling a vac on tank. Which after shutdown would pull the gas back.

I've never had a see thru filter, but if memory serves me correct, the friends that have had one stated that they never stayed full of fuel. How does it run, like it running out of fuel. If it has the stones like you think it should, perhaps it ok.

Dave

I would get rid of that glass filter. They can crack or break, spilling gasoline over a hot engine. Replace it with a metal or polymer housed filter.

The filter will not ever be "full" of fuel, running or not. The lowering of the fuel level in the see-thru filter after shutting off is normal, as there is no pressure there to keep it in the filter. No foul play going on here!!
I have to agree with 'Slinger on the glass bowl.