Different bird similar story. 1978 Bellanca 7GCBC had flap gap seals on wing bottom riveted to rear of wing. NACA 4412 airfoil with no washout from the factory and flaps 0-35*. Allegedly the seals helped climb and cruise, and the flaps were mainly for drag. Among some experiments I did a series of ROC, TIAS cruise speed, and stalls.

I began the 2nd stall series by first removing the seals on the right wing. The plane rolled to the left away from that wing upon flap deflection. I assumed more lift from that wing was the reason. I noted no detectable change in ROC and speed but that was in pre-GPS days. I felt they slightly helped lift and left them off until resale. I wanted increased lift more than other potential features. There was no increase in tail buffeting or blanking at full flap deflection which sometimes changing flap design can create.

Gary