Tuning Doing some 1322 valve mods...

[Long_Gun_Dallas]

Basically istalling a pin to fill the valve inlet hole, and reduced the size of the inlet seal by 2/3. Recently saw the same mods done by someone else, so not my idea. Also aquired a dual seal flat piston from mountain air custom. 

Inlet hole is 1.75x10mm. I am going to get a 1.75mm drill bit, and then cut the back of it off to install. This should net some nice gains in terms of power per # of pumps. Gun used to top out at 15fpe.... we will see what happens... But have to wait on post to deliver the drill bit first. I had a 1.5mm pin laying about, but it's not quite big enough.

 

[Arzrover]

Seems like the oring head is going to limit power the same as having the txfr port too large...

You'll likely see a very small increase, regardless. Nice looking setup

Bob

 

[Long_Gun_Dallas]

Indeed. But should still be a decent improvement if done correctly. I figure 1.75mm may be too tight. Need a little room for air to get into the valve, so there will be some testing and likely modification. I have lapped the piston to the valve face as well, so they are very snug. But yes, the oring seal does leave a bit on the table. But I can think of more than one workaround that will make up for most of that... 

 

[Long_Gun_Dallas]

Bit came in, and is installed. (I have yet to trim and polish it flush) I had to bore the hole a little as the bit was larger than 1.75mm? I also used some lapping compound to open the hole a tiny bit more so air could get in. I'll have to test it and see if I need to open it further. I did an experimental mod (not pictured) to reinforce the large valve to tube oring. Orings do flex some, if they flex too much they will split.