Tuning New Out of the Box QB 78 --- Archer Valve vs. Original (new) in Rifle

[pecci]

I want to do a few mods to increase power a bit. Is it advantageous to replace orig. valve, with Archer's valve? Is there a quality or construction difference between them that would set them apart?

Should I install a new Archer's, or just remove the "linty" material from the original & use it that way?

Much appreciated!

 

[nervoustrig]

The replacement valve is all about improving air flow. If you are mechanically inclined, you can do it yourself. Lots of people, present company included, have done it with a drill, Dremel, and files. It does not have to be pretty to work great. Just take care not to damage the valve seat and you’ll be fine.

 

[biohazardman]

Valve mod stuff;

https://www.airgunnation.com/topic/crosman-2240xl-2/?referrer=1

 

[pecci]

I should have mentioned that I already have a recently purchased Archer's valve. My question: Will my new Archer's valve outperform the new stock valve already in the rifle?

Sorry about the misunderstanding. I appreciate the efforts. 

 

[nervoustrig]

The aftermarket valve will most definitely flow better than the OEM valve. Higher velocity / energy, lower shot count.

Note there is an excess of hammer strike as delivered...meaning the valve stays open after the pellet has left the barrel. So not only is it a waste of CO2 but it also exacerbates the self-cooling effect which can rob velocity and hamper the extreme spread. If you want it to run more efficiently, clip a half coil at a time from the hammer spring and fire a few test shots. Continue until you just begin to see a drop in velocity of 20fps or so. That's the sweet spot. Can always add a flat washer or two if you go a smidge too far.

That's the simple brute force approach. Other ways are more elegant but require a little fabricobbling. One way is to remove the rear cocking pin to convert it to cock-on-open, and drill and tap the end cap for a #10-32 screw to fine tune hammer spring tension. Or if you really want to go all out, make an SSG to give the hammer a smidge of free flight to eliminate wasteful hammer bounce.

 

[pecci]

Great info, It is all much appreciated.

 

[pecci]

If you want it to run more efficiently, clip a half coil at a time from the hammer spring and fire a few test shots. Continue until you just begin to see a drop in velocity of 20fps or so. That's the sweet spot. 

I don't quite understand the above.

As you clip "half coils" wouldn't the fps increase? Then are you saying that continuing to clip will eventually begin to decrease fps?

 

[nervoustrig]

To say it differently, shorten the spring a little bit at a time. Shortening it produces a weaker hammer strike, reducing valve lift and dwell (so as to not waste CO2), and eventually reducing the velocity.