New build

[rangerfredbob]

before taking it back apart, try cocking the hammer first before pumping... if that doesn't work there's probably something small on the exhaust valve seal

[temchik]

Ok, it was leaking from the front, not the transfer port... I opened it, there's some metal debris in there, cleaned it, lubed the seals... Still leaking.... Quickly pumped several times and fired, bam! not leaking anymore... whatever was obstructing the check valve is now gone, I suppose

[temchik]

All right. The proof is in the pudding:

3 pumps = 300fps
5 pumps = 390fps
10 pumps = 490fps

It seems I *lost* 10fps full power and 20fps on 3 pumps compared to the stock valve. Yes, I adjusted the piston without the seal to make sure it is touching the valve face without the arm closing (about an inch off the tube).

This is... well... disappointing at bit... I thought that an FT valve is going to improve pump efficiency, maybe not by much, but still... To see ZERO improvement...

[temchik]

So I adjusted and readjusted the piston and re-chronied it about 10 times now. No Change whatsoever...

[arkmaker †]

Same transfer port, same probe, same type and weight of pellets? Anything restricting the flow between the valve port and the barrel? Whatever freed up so you can make a seal might have gotten stuck in the TP or valve outlet port. Don't know without seeing, just saying what I would check.

[temchik]

I think MA valve outlet is drilled out a bit, long probe, same port and pellets.

Am I supposed to see any improvements at all?

ETA: well. I see one improvement, I can now pump to 16 pumps and still dump all air, but I was really expecting more efficient pumping, given that the valve is unmodified inside

[BillK]

As has been said before, all guns are different. (could be the difference in valve/hammer spring tolerances)
The same mods offer different results.
As there was some derbies in the valve it could easily comprised the Orings on the valve &/or piston.
Be sure to debure the air tube so the new Orings are not scored. (remove the valve & hammer to do the deburing & clean tube thoroughly)   
Deburing  is done by using fine grip sandpaper on a dowel and smoothing the edges (all of them) in the air tube.  Starting at the open and finishing at the pump tube pump arm opening.

http://www.theoringstore.com/index.php?main_page=index&cPath=367

These are the Orings I use.  70 Duro for the piston and 90 Duro for the valve.  Urethane (white) type for each.  You can't get much better.

[arkmaker †]

There is a thread on here that shows what someone did to get his pumper set up for minimum pumps (I think it was 3-4) and shooting speeds for 10M target. If that is what you are after, then that post might be of help long term. I will try to find it and post the link.
Rich

EDIT: Here is the link.......
https://www.crosman-air-pistol-owners-forum.com/board/index.php/topic,4088.msg40044.html

Also, take a look at WyoMan's Stickies in the pumper section for even more ideas

[temchik]

I de-burred everything prior to doing any work. Re-inspected all seals again, all look good, I actually have 70d and 90d urethane spares somewhere..

As has been said before, all guns are different. (could be the difference in valve/hammer spring tolerances)
The same mods offer different results.
As there was some derbies in the valve it could easily comprised the Orings on the valve &/or piston.
Be sure to debure the air tube so the new Orings are not scored. (remove the valve & hammer to do the deburing & clean tube thoroughly)   
Deburing  is done by using fine grip sandpaper on a dowel and smoothing the edges (all of them) in the air tube.  Starting at the open and finishing at the pump tube pump arm opening.

http://www.theoringstore.com/index.php?main_page=index&cPath=367

These are the Orings I use.  70 Duro for the piston and 90 Duro for the valve.  Urethane (white) type for each.  You can't get much better.

[temchik]

Thank you, I guess I was working under false assumptions that an FT setup is more efficient than the stock one. At least the piston is more rigid, and there is no cup seal so it will last longer.

Pumping is quite a bit harder though for some reason

There is a thread on here that shows what someone did to get his pumper set up for minimum pumps (I think it was 3-4) and shooting speeds for 10M target. If that is what you are after, then that post might be of help long term. I will try to find it and post the link.
Rich

EDIT: Here is the link.......
https://www.crosman-air-pistol-owners-forum.com/board/index.php/topic,4088.msg40044.html

Also, take a look at WyoMan's Stickies in the pumper section for even more ideas

[arkmaker †]

Normally, I think that assumption is correct. There are so many little things that can change all of it. Keep working on it. Search is your friend on the CAPOF. If it can be done, chances are pretty good that someone has done it and written about it  here.

A couple of years back, I built a pumper for my friend. Made him a brass flat top piston, hogged out the valve with all the trimmings and I ended up showing great results. I just finished up one a couple of weeks ago and the results are not as good. A bit disappointing to be honest. I will wait until I have the pateince to dive back in to it. It will bring a smile to my face yet! 

[CraigH]

I have a 1322 carbine with FTP and Boss Buddy.   The valve has a 90D o-ring and I first had a 70D on the piston but changed it to a 90D.   Not much if any difference with either - I think it pumps smoother with the FTP.   I am however disappointed with the performance - not getting 600 fps.   I do have the disadvantage of 5835 ft elevation, but perhaps the limit of the elevation and 14 inch barrel have been reached.

I highly recommend the three-part sticky by WyoMan.   My 1322 has all his recommendations and I have also installed two side pins to the valve.   This last because of the following very interesting read:

http://www.gatewaytoairguns.org/GTA/index.php?topic=77463.0

[temchik]

Yes, I saw this thread and that's what I based my assumptions on. BUT.. My stock piston looks a little different than anything I find on the internet, it is possible that Crosman had redesigned it and reduced the headspace on new pistons making it much closer in performance at recommended number of pumps with any aftermarket piston/valves.



Notice, there's no cup pin and the piston looks like one-piece without any sections.

[temchik]

Also want to share a couple of things:

Mellonair main pin nuts are pretty big, had to sand down the end of the pump arm. Also, the pin holes on the tube are not exactly 3/16", so they had to be drilled out a bit and cleaned



And I sanded down the stock, it's a bit more comfortable now, but it's still too shallow... I am thinking of grinding down the bottom part and filling it with something:

[CraigH]

Crosman did upgrade the piston and the barrel band / pump pivot rigidity along with the cosmetic upgrades on the new version.