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Thread: Crosman 140

  1. #1
    Senior Member Doc Sharptail's Avatar
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    Crosman 140

    This is one of the later versions with the up-graded trigger group.



    Dunnville roll stamp:



    Front sight:



    Rear sight:



    Those rear sight screw holes go all the way into the bore. I haven't benched it yet.

    For those of you wondering why sometimes these won't cock properly, it's because the sear block gets installed backwards. The fix is simple.

    This one still needs a bit of tlc to get it up to power. It's to the point where it will hold air, and it does 440-460 at five pumps, after a good clean 'n lube.

    Ten pumps, and the velocity drops to 420-430, with the gun blasting air out through the trigger group opening. On my 13-XX's this behavior indicates valve stem troubles. On this I'm suspecting it would be the quad seal ?

    I should have taken pics of the piston and valve face when I had it apart.

    I'm still pretty happy with this latest acquisition. For a gun this old to be still throwing pellets down range without anything new being added to it is on the amazing side.....

    Regards,

    Doc Sharptail
    "Ain't No Half Way"

    -S.R.V.

  2. #2
    Senior Member SeanMP's Avatar
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    Doc that's a beauty for sure.

    Are you going to do a full restoration job on it?
    Sean

  3. #3
    Moderator rsterne's Avatar
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    I love the old 140s.... they frequently have some beautiful wood hiding under the rather blah finish....

    Bob
    Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
    Airsonal: Too many to count!

  4. #4
    Senior Member Doc Sharptail's Avatar
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    It won't be for a while until I get to the wood and metal refinishing. I took the gun apart again tonight, and did a couple of minor replacements. The sear block spring and quad seal cup o-ring got replaced. I made up a poly tube transfer port for it. The two cemented together o-rings that were used as a seal were pretty flaked out.

    The gun quit blowing air out the trigger group opening. 5 pumps now give me 460 fps. I'm still getting a velocity drop at 10 pumps- down to 430-440 fps. I'm probably going to have to think about this for a while.

    Here's a look at the piston face:



    And the valve face:



    The valve looks just like a 13-XX valve on the front section. There's even a trigger guard screw hole on the side opposite the stock screw stud hole.

    It looks like my repair options remaining are the following:

    Go to a flat top piston.

    Replace the valve check button and spring.

    Replace the valve o-ring that goes over the threads on the body.

    And replace the quad seal with a new one...

    Regards,

    Doc Sharptail
    "Ain't No Half Way"

    -S.R.V.

  5. #5
    Moderator rsterne's Avatar
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    I found the flat-top piston worked well.... I machined off the front retained for the cup, left the felt wiper in place, pressed on a new aluminum front section, turned it to length and turned an O-ring groove in it....



    Bob
    Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
    Airsonal: Too many to count!

  6. #6
    Senior Member Doc Sharptail's Avatar
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    I ftp'd it last night, and I'm floating. Huge improvement. I'm seeing upper 520's for 10 pumps with the 14.3 gr. Daisy h.p.'s. The gun hasn't been ported in any way, and my first polytube transfer port is a bit on the wonky side...

    I'll get back to this with a few more pix later on, but for now, hi-ho, it's off to work I go :P

    Regards,

    Doc Sharptail
    "Ain't No Half Way"

    -S.R.V.

  7. #7
    Moderator rsterne's Avatar
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    Great that you got the FTP working.... Does your 140 have a sleeve inside the valve to reduce the volume?.... If so, take it out.... You will make the gun easier to pump, with a lighter trigger pull, and the velocity will continue to build more past 5-6 pumps.... Typical numbers for the ones I did are.... 515 at 5 pumps, 610 at 8 pumps, and 660 at 10 pumps.... the strongest one topped 700 at 10 pumps, but had a bored valve.... Some other things you can try....

    Drill out the flow-through bolt to 5/32" front and bottom....
    Drill out the end of the valve (the part the quad seal slides over) to 5/32".... using numbered drills, ONE SIZE AT A TIME.... go slow so you don't expand the outer surface....
    You have already fitted a poly-port, but make sure the barrel port is also drilled to 5/32" (again, one size at a time, making sure the drill doesn't grab and damage the opposite side of the rifling).... Carefully deburr the inside of the port to make sure it doesn't damage the pellet on loading....

    The extra volume inside the valve by removing the sleeve reduces the pressure at a given number of pumps, which reduces the trigger pull.... The velocity is unaffected at about 5-6 pumps, tends to be better above that, but slightly slower at 2-4 pumps....

    Bob
    Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
    Airsonal: Too many to count!

  8. #8
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    Hum well sound like your on the right track .Here a pic of the last few pumpers i worked on



  9. #9
    Senior Member Doc Sharptail's Avatar
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    Lauchlin posted pumper eye candy again

    Must be a lot of fun shooting those, if my little 140 is any sort of a measuring stick.

    The gun is hitting hard now. It still has some issues. I think I'm going to quit fooling around with the poly tube, and order in a proper 22-XX metal tube and seal for it, and be done with it.

    I pinched my hand in between the stock, and pump handle on Wed. night. I got a pretty fair blood blister in the palm of my hand, but worse, the pump handle wood chipped away at the pinch zone.



    The damage is not as deep as it looks in the photo. I think the camera sets to f-4 automatically on close-up mode. I should be able to fill and sand that in, with it not showing too much. Needless to say, the wood is incredibly dry. I think a strip and refinish with quality wood oil is definitely going to be needed.

    There isn't much point in me benching this little gem- my eyes just aren't up to it. Here's next best- off-hand kneeling at 7 meters...



    It seems to like the daisy h.p.'s. 3 went into pretty tight, and the other 2 are geezer eyes...

    As for power:







    All 5 of the h.p.'s went through both the bottom and lid of this fairly hard salmon can at 12 Meters- 7 pumps. If I can get within 10-12 meters of a grouse with this thing, it's dinner time!

    I'd like to replace the sear block spring again, with something a bit stiffer. The replacement I used bunches up a bit more than it should. I think I should try a section of 13-XX hammer spring in there- should be about right tension wise. I also want to replace that quad seal...

    The bbl on this is only 20.5 inches long. I'm a bit taken a-back at the velocities I've been wringing out of it. Weight is just right for hurried off-hand snap shootin at those trophy food tins. I'm falling hard for this 140, and am not too sure I want to put it down any time soon. They say you can't go back to your childhood, but what the heck do "they" know?

    As for porting/tuning/souping up goes.... I haven't decided yet. I have a few more projects that are a bit better suited to handling power, but you never know...

    Pump resistance starts getting heavy at 5 pumps, and I've never seen anything like this in my 13-XX's. Like I say, I'm reserving that decision on power, for the time being....

    Regards,

    Doc Sharptail
    "Ain't No Half Way"

    -S.R.V.

  10. #10
    Moderator rsterne's Avatar
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    Like I said, if it has that sleeve inside the valve, pull it out and try it.... you can always put it back if you want.... I've found it increases the velocity over 6 pumps, makes it easier to pump, and reduces the trigger pull weight.... Where is the negative in that?....

    Bob
    Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
    Airsonal: Too many to count!

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