[MikeK]

I'll stick with a burnished and properly seated steel pin/brass seat valve. Fine rust particles cannot imbed as with softer polymer needle seats. Both Tom W and I have posted in the past about fixing original style steel pin valves. They reliably seal drip-tight and do not stick or glue themselves to the seat if left for extended time.

I don't like the grosse-jet type either. On rare occasion they can get their balls in a knot. When they do work (99.9+% of the time) their steel-to-brass seat is as drip tight as a steel pin valve and they do not suffer rust particle embedment like polymer tip valves.

Viton as a bag of worms. A DuPont trademark, they define 8 grade categories, with multiple formulations in each. Only two, grades "F" and "GFLT" are rated for low fuel permeation (swell resistance) and use with alcohol blend fuels. Many 'Viton' valves fail because they are made with cheaper, wrong, or knock-off fluoroelastomer blends from other manufacturers. If it is an OEM needle from a current (alcohol blend fuel era) carburetor manufacturer the right stuff is used. ANY other aftermarket supplied 'Viton' needle is a crap-shoot.