Using Diskette to Make O Rings

I was trying to use extended tank motor. Nice unit with number one cylinder and all. But the plastic spacer bridging between the tank venturi and the backplate is old and slightly flared at one end due to age. I lathed a new spacer piece as seen in the picture from copper. Then the normal o ring for the venturi was getting squeezed too much. I used a hole punch and used some diskette membrane for that. Seems to be working real good. Does anyone have any experience with that? I have used diskette membrane in some widows for the reed valve and frankly I thought it ran awesome.

Any thoughts will this membrane work as a sandwiched O-ring very long immersed in the tank like that? It definitely holds up as a reed valve for more than 30 runs at least from my experience.


Thanks
Iceberg