Return to Index  

I take a page from Tims book when modding the QB valve

December 14 2011 at 12:07 AM
scot laughlin  (Login classicalgas)

Response to Thanks, Scot...

I use a piloted spot face cutter to cut the seat flat and true to the stem bore.Then I undercut the head about 3 degrees..according to LD that makes the seal more reliable.I also make the head narrower at the seat,sort of an ice cream cone shape, and adjust the large end clearance to the valve wall in small increments to get the balance of power and shots I want. This is for a self reg valve, but it may help even with a constant pressure.

I also do something I've never seen mentioned...siamesed ports. I cut the barrel back (on a new one I'll turn it to a tight fit and lap it into the o-rings and no play)partially drill the port,dremell a small plenum there and drill two tiny pilot holes into the bore, with a bridge between them. Then some work with diamond dental burs under magnification to smooth it all up. Final finish in the throat with a long tapered reamer. You can get a lot of flow with no pellet hang ups that way.

I'm a fan of wire probes, especially in .177

This message has been edited by classicalgas on Dec 14, 2011 12:16 AM

 Respond to this message   


JK's Airgun Forums, moderators, and administrators are not responsible for any problems that may occur from reading or using content posted on this forum, as they are the exclusive responsibility of two parties: the person who posted it and the person who acted on said posted information.Use of our forums by people under 18 years old is allowed only with legal guardian(s) present..