by B.B. Pelletier

Part 1

This is part 2 of the Career Infinity report. Normally, I’d be testing velocity, but something came up. Today I’m going to take you on a short excursion inside a gun, to show you a little about how they work and also how easy they are to repair.

You see, when I tried to fill the test rifle for velocity testing last week, the inlet valve wouldn’t accept air. Then, at around 3,000 psi, the inlet valve suddenly popped open and accepted a fill of about 1,000 psi inside a few seconds. It seemed clear that the inlet valve was sticking.

When I tried to bleed the fill clamp, the air never stopped–a sure sign that the inlet valve was now refusing to close. So, the rifle lost its entire fill. I then sat looking at the gun for many minutes, trying to decide what to do next. That’s not unlike what many of you would do when something similar happens. Normally, I would have boxed up the rifle and shipped it back to Pyramyd Air, but this time I noticed that the design of the Infinity inlet valve is quite simple and straightforward, as though it was built to be repaired. I partially disassembled it and saw that it was as simple as I had imagined, so I thought this time I would fix it myself and let you see what’s involved.

A call to Boris at Pyramyd Air got me the parts I needed. They turned out to be a simple o-ring and the inlet valve seal. We’ll do velocity next time (which won’t be long now that the rifle is fixed).

The inlet valve body is aluminum and very straightforward. It screws into the air reservoir tube and two o-rings seal it. Taking it off required one 10″ channel-Lock pliers and a leather belt to keep the jaws from marking the valve body. Everything came apart easily, and I confirmed that the inlet valve seal was the cuplrit.

I’m going to show you the rebuild in pictures.


The reservoir tube awaits the inlet valve body.


We’re looking at the reservoir side of the inlet valve body. This deep hole is where the valve parts go.


The valve body contains these three parts. A brass holder holds the inlet valve seal (left). This is the bad seal that I will show you when I remove it. In the middle is the inlet valve return spring. On the right is the threaded keeper that holds these parts inside the inlet valve body.


Here we see the old seal (right) and the new seal installed in the brass holder. The seal isn’t supposed to have that deep groove in the center.


Here I’ve dropped the new seal in its brass holder into the valve body.


And now the return spring is dropped into the hole.


The keeper is the last part to be installed. Once it’s threaded in the hole, the inlet valve assembly is complete.


Now the valve body is screwed back into the reservoir. Both o-rings around the outside of the body (one shows here) have been lubricated with diver’s silicone grease. The body threads into the reservoir by hand until this o-ring makes contact.


To screw in the valve body the rest of the way, channel-lock pliers are used with a leather belt in their jaws to prevent marks to the aluminum valve body. You make very small movements this way because of the barrel, but there isn’t much to do.


The valve body is installed. Now it’s time to install the barrel hanger and the inlet port.


The inlet port (shown upside down so you can see the seal) is now screwed into the valve body.


The inlet port is back on and the barrel hanger is attached. This job is done!

Are we done?
I aired up the rifle to 2000 psi and it held fine, so this job is done. Start to finish was probably an hour, but the reassembly seen here took 30 minutes with the photography. Writing the blog took a lot longer.

Why did I show this to you? Because in all honesty, things like this happen sometimes. I knew this one was simple, and I wanted to show you what that means. The keys here are cleanliness and lubricating with silicone grease.