In addition to reprofiliing the threads and enlarging the discharge port, other internal modifications need to be accomplished. The retaining plug for the pin needs to be drilled out to increase flow and the pin itself must be modified for a thinner stainless steel shaft. I drilled the retaining plug out to 0.190 which still allows the use use of the allen key for removal.
Next is to remove the seal and trim the pin to just above the shoulder that retains the seal.
This next part will either require a lathe or a steady hand for the drilling of the replacement pin. Thankfully I have drilled out plenty of rivets in my career as an aircraft mechanic and since I do not have a lathe I reverted to my old skillset. The replacement pin is a section of 1/16 stainless rod. Converted to metric is 1.587 mm, I used the 1.6 mm bit from my Dremel 7 piece metallic bit set.
The end result was rather satisfactory but you must be sure to drill deep enough into the body of the valve to properly support the new pin that will be soldered in place.
The black mark on the stainless rod indicates the top of the newly trimmed shaft indicating the depth of the hole.
To be continued…….
Patrick Carroll 