Canadian Airgun Forum

The #1 Community for Airguns in Canada!
It is currently Fri Nov 22, 2019 10:26 am

All times are UTC - 5 hours


The Canadian Airgun Forums are a place for people to discuss and learn about airguns and the airgunning sport in Canada. There are lots of discussions about airguns, airgun accessories, reviews, modification and repair information, airgun events, field target and free classifieds!

 

You need to register before you can post: click the register link to proceed. Before you register, please read the forum rules. By joining our free community you will have access to post topics, communicate privately with other members (PM), respond to polls, upload your own pictures, and access many other special features. Registration is fast, simple, and absolutely free! To start viewing messages, select the forum that you want to visit from the selection below.








Post new topic Reply to topic  [ 11 posts ] 
Author Message
 Post subject: Crosman 140 Valve Repair
PostPosted: Tue Jun 18, 2019 9:11 pm 
Online

Joined: Mon Jan 22, 2018 6:34 pm
Posts: 14
Location: Ontario
Getting back to finishing my 140 restoration. I had trouble with the gun building pressure after I had replaced all the o-rings. Assuming I had pinched an o-ring I replaced them again with the same results. I had to build a little testing fixture to test the valve out of the gun and found the aluminum valve had cracked. After building a new piece tested again and no leaks. I used my nitrogen tank and regulator from my A/C repair days and checked it @ 300 psig. Now to put the gun back together and further test my work. I will keep you posted.


Attachments:
DSCF0659 - Copy.JPG
DSCF0659 - Copy.JPG [ 259.48 KiB | Viewed 1041 times ]
DSCF0660 - Copy.JPG
DSCF0660 - Copy.JPG [ 254.93 KiB | Viewed 1041 times ]
DSCF0654 - Copy.JPG
DSCF0654 - Copy.JPG [ 213.68 KiB | Viewed 1041 times ]

_________________
Kevman

Benjamin Classic .22
Umarex Colt 1911
QB78D .22
Top
 Profile  
 
PostPosted: Tue Jun 18, 2019 11:27 pm 
Offline

Joined: Mon Aug 15, 2016 11:00 pm
Posts: 317
That's a nice test rig you have there


Top
 Profile  
 
PostPosted: Wed Jun 19, 2019 3:52 am 
Offline

Joined: Thu May 07, 2015 8:30 pm
Posts: 1188
Location: Eastern Townships
pistolero wrote:
That's a nice test rig you have there


Yup, and very good work on the valve too!


Top
 Profile  
 
PostPosted: Thu Jun 20, 2019 7:11 pm 
Online

Joined: Mon Jan 22, 2018 6:34 pm
Posts: 14
Location: Ontario
Thanks, I do enjoy figuring these things out. This forum is a great resource.

_________________
Kevman

Benjamin Classic .22
Umarex Colt 1911
QB78D .22


Top
 Profile  
 
PostPosted: Sun Jun 30, 2019 8:06 am 
Online

Joined: Mon Jan 22, 2018 6:34 pm
Posts: 14
Location: Ontario
The rifle is back together and working great. Here is what i got over my chrony with 14.3gr Crosman pointed.
5 pumps 510, 509, 505, 510, 506. Average 507 fps.
10 pumps 610, 616, 613, 624, 633. Average 619 fps.
15 pumps 688, 693, 708, 706, 701. Average 699 fps.
20 pumps 730 fps. 1 shot @ 20.

Not sure where this ranks but I am happy with the results. This is with the flat top aluminum piston I made. I did not try it with the original type piston.


Attachments:
DSCF0669.JPG
DSCF0669.JPG [ 190.57 KiB | Viewed 910 times ]
DSCF0671.JPG
DSCF0671.JPG [ 187.71 KiB | Viewed 910 times ]

_________________
Kevman

Benjamin Classic .22
Umarex Colt 1911
QB78D .22
Top
 Profile  
 
PostPosted: Sun Jun 30, 2019 5:43 pm 
Offline
User avatar

Joined: Wed Oct 17, 2007 3:27 am
Posts: 2586
Location: Winnipeg, Canada
I can just imagine the trigger pull weight at 20 pumps...

I would advise against over pumping on these oldsters. Some of the pump tubes are a bit on the thin side, and it's easy to over do it in the quest for velocity. The original valves were set up to pass air after reaching a certain pressure/# of pump strokes to protect the valve from locking closed on high pressure. Sort of suspect the valve in your gun may have been modified at some point. 580-620 is normal max velocity for these, depending on pellet weight.

-D.S.

_________________
"Ain't no half-way"
-S.R.V.


Top
 Profile  
 
PostPosted: Mon Jul 01, 2019 6:33 am 
Online

Joined: Mon Jan 22, 2018 6:34 pm
Posts: 14
Location: Ontario
I didn't modify the valve at all other than copy the cracked part. I tried to keep the internal dimensions the same.Any more than 10 pumps does make the trigger difficult to be accurate. The old gun does shoot good. If I was going to keep it I would have to look into changing the breach and adding a scope. My intention was to just get it back close to original condition. I didn't like the pump seal and the piston was an easy upgrade. Thanks for the reply.

_________________
Kevman

Benjamin Classic .22
Umarex Colt 1911
QB78D .22


Top
 Profile  
 
PostPosted: Sat Jul 20, 2019 10:39 am 
Offline
User avatar

Joined: Mon Jun 16, 2008 4:36 pm
Posts: 710
Location: nvvan
Mr. Marvin has one for sale right now I noticed. But it is also not holding air. I wonder if it has a cracked valve as well?

_________________
I machine, I build , I shoot
Sent via Flux Capacitor uF


Top
 Profile  
 
PostPosted: Sun Jul 21, 2019 4:18 pm 
Online

Joined: Mon Jan 22, 2018 6:34 pm
Posts: 14
Location: Ontario
I could test a valve for someone or they could borrow the tool. I found the leak with compressed shop air @ 130 psi and tested with nitrogen (just because I still have it). Contact me if I can be of any help, I have learned a lot on this forum and it would be great to give back a little. Kevin.

_________________
Kevman

Benjamin Classic .22
Umarex Colt 1911
QB78D .22


Top
 Profile  
 
PostPosted: Wed Sep 11, 2019 6:30 am 
Offline

Joined: Tue Feb 18, 2014 7:24 pm
Posts: 667
Location: Dowling ,ontario
I just did a 1400 Sears and I really like it . I was going to put it in my truck for bird hunting but it turned out so well it’s my dedicated window sniper . Nice and quiet and super accurate out to 20 yards with the 15.9 JSB pellets . If someone were to figure out a fix for the horrible trigger , I’d be all over it . Sure there good to about ten pumps but after that , way too heavy of a pull for any type of accuracy .

_________________
Not quite done collecting


Top
 Profile  
 
PostPosted: Wed Sep 11, 2019 9:45 pm 
Offline
User avatar

Joined: Sat Nov 03, 2007 4:19 pm
Posts: 8979
Location: Coalmont BC
Here is one I did a long time ago.... I used a modified Disco style breech so that I could mount a scope on it.... Some of the old Crosmans have gorgeous wood, if you take the time to strip the stock and refinish it....

Image

Inside I used a flat topped piston and enlarged the ports to (if I remember correctly) 5/32"....

Image

Yes, the trigger pull is ridiculous at 20 pumps.... The gun is a good candidate for a "blow-open" balanced valve to reduce the load on the sear.... just in case anyone is so inclined....

Bob

_________________
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal;
Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!
Proud Member of the 2000+fps Club!


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 11 posts ] 

All times are UTC - 5 hours


Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
News News Site map Site map SitemapIndex SitemapIndex RSS Feed RSS Feed Channel list Channel list

Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group

phpBB SEO