Why a Delrin/Teflon Valve stem in a QB?

[dryanw]

Just wondering what the advantages are....

[wilsonj1018]

well the stock stems are said to not last very long on higher hpa pressures. derlin will last longer than the gun probably, but it is hard to seat. teflon on the other hand will last a good long while and seat well.

[TimmyMac1]

Teflon overcompresses and it is nearly void of memory. It makes a great inlet seal for Multi pumps but it is too soft for an exhaust seal IMO. The Best for HPA is D scale 75 durometer Urethane. I have valve heads ansd seals that fit good and can use the factory steel stem part in them. If you do delrin it has to be precision or it will not seal whjen it turns. Seat must be dead true and sharp edged.
The same seal is used in All Crosman CO2 guns I do and the QB guns as well. I have several brass heads for the different styles but all ther Heads take the same universal seal. Been at this a while and found this to be the best solution by far. It is far easier to get soft seals to work and hold tight but the best performance and logeivity comes from a precision valve seat and considerably harder seal than the Chinese use.
Felrin can work but it must be Virgin White. No Black Delrin in CO2 systems is going to work well.
Too porous.

TimmyMac1