FINALLY! The 'missing' SILCA gasket is back in production. There are at least 3 original brass chucks that use this gasket as well as the Impero frame pump. However, none of them were as widely sold as the Presta Only chuck and we had been unable to find original 323 gaskets that were unused and in near original condition to assess performance, so the team at SILCA had to completely redesign and optimize this part from scratch.
This modern 323 gasket has been developed using the same high-tech fully synthetic elastomer used on our modern 242 gasket on the SuperPista ultimate. We find that this material allows for greater valve holding power, greater sealing and significantly improved life expectancy. New 2-stage Seal Design improves high pressure performance and also makes it unnecessary to press the chuck on as far as the original design required. With a 323 gasket your classic SILCA pump will literally perform BETTER than new!
This is the gasket you need if you have any of the chucks shown in the images, they all share the feature of being reversible so that you can take out the gasket and other inside pieces and flip them over to convert the chuck from presta to Schrader. We know of the 3 models shown in the photos, but amongst these there are at least 6 variants of the plastic pieces that go inside the chucks. We are not able to remake any of the plastic pieces from inside these chucks. If your plastic pieces are broken you can still use this gasket to keep your chuck presta compatible but Schrader will not be an option.
If you need Schrader compatibility we recommend the Thread-On Schrader Chuck with 17-4 Presta Chuck as a solution. This isn't the least expensive option, but both chucks are all metal and will last an eternity.