I dimly remember that either there might have been a rubber bumper/seal on the lip of that flapper, or, that someone reported putting a seal on that "lip".

The might have used a heat resistant tube with a slit cut from end-to-end?

Maybe I am dreaming?

Tim
1954Advance-Design.com
1954 3106 Carryall Suburban
1954 3104 5-window pickup w/Hydra-Matic
The 216 and early 235 engines are not "splash oilers" -- this is a splash oiler.