Installing a Delrin Needle in the Stromberg carburetor.
Stainless Needles were first, Neoprene tipped came later with superb sealing capabilities, but limited lifetime, Delrin was the latest addition with good sealing and chemical resistance. The Delrin or steel needle is required for autogas STC. The neoprene tipped needle will deteroate if alcohol gets in gasoline. Also, the seat is different for the steel needle. An upgrade from the neoprene tipped needle to the delrin needle can be done without changing the seat. Here is how to install a Delrin needle..
The carburetor here without a mixture control.
Taking it apart
The Neoprene tipped needle without the tipping.
Balance weight needs to be added , since the Delrin needle is lighter than the original steel needles.
Safety the needle seat properly.
Make sure the travel of the float is free all the way.