Buoymaker - the following from the YF lecture in my Carter Carburetor School textbook:

"The long-extension on the seat acts as a stand-pipe for the incoming fuel, to allow any small foreign particles to settle around the extension rather than come past the needle. 'The extended type seat can be used only with the bowl covers which have sufficient space for the extension (some models do not provide for this type needle seat.)".

And thank you for the complement!

Jon

Good carburetion is fuelish hot air
The most expensive carburetor is the wrong one you attempt to modify.
If you truly believe "one size fits all," try walking a mile in your spouse's shoes!
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