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PostPosted: Sat Nov 22, 2014 3:18 pm 
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Joined: Fri Sep 02, 2005 8:16 pm
Posts: 136
Location: CANADA
HI:The cup seal and all related seals have been successfully changed.I now am on to putting the pump lever back in the tube and securing it with the pin.I have looked at the Crosman instructions on the procedure but I thought I would ask the population at large as to the best method of setting the valve face/pump face clearance.I know that you don't want contact with the exhaust valve but...
Thanks again for the collective guidance.
Bernie


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PostPosted: Sat Nov 22, 2014 10:24 pm 
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Joined: Wed Mar 27, 2013 9:51 pm
Posts: 85
Location: California USA
Actually you do want some contact between the pump and valve. The way I set the pump is, run the pump piston into contact with the valve without the pivot pin in place. Then look through the pin hole at the alignment. The pump arm hole should be a few thousandths higher than the tube holes. This will get you very close to the proper "preload"when the pin is reinstalled.


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PostPosted: Sun Nov 23, 2014 12:01 am 
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Location: Alberta
Well said BBB
No idea how some folks decide what they KNOW before advice is given.
Poor manners.....

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PostPosted: Sun Nov 23, 2014 12:54 am 
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HI Big Bore Bart:Thanks for the heads up.I need a little clarification of terms."Then look through the pin hole at the alignment". Is that the oil hole or...?
Thanks
PS Voltar in a previous life I designed pneumatic actuators for damper systems and in those instances pistons and valves were not bed follows.

Thanks again for the collective guidance.


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PostPosted: Sun Nov 23, 2014 5:15 pm 
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Location: Winnipeg, Canada
You do need a little contact tension, even with a cup piston~ to hold the fore-arm in the closed position.
Didn't run into trouble with this on my 140 until I changed to flat top.
I've also found that with a cup piston, the arm should fully close on each stroke while pumping,
in order to arrive at some semblance of shot to shot velocity consistency... this was really obvious over the chronograph.

Regards,

Doc Sharptail

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PostPosted: Sun Nov 23, 2014 5:34 pm 
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Location: CANADA
HI:Thanks for the insight.The stem of the pump extends out a few thou beyond the piston cup seal so even if there is minimal contact with the exhaust valve face the cup edge would have clearance.
Nothing beats experience of doing "it" what ever "it" is.
Thanks again.
Bernie


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PostPosted: Mon Nov 24, 2014 1:16 am 
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Location: California USA
bernie wrote:
HI Big Bore Bart:Thanks for the heads up.I need a little clarification of terms."Then look through the pin hole at the alignment". Is that the oil hole or...?
Thanks
Thanks again for the collective guidance.


Tis the pivot pin hole one would peer through to check for alignment. :drinkers:


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PostPosted: Mon Nov 24, 2014 1:39 pm 
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HI:Thanks for the clarification!!!
Bernie


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PostPosted: Mon Nov 24, 2014 1:50 pm 
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Location: Alberta
bernie wrote:
HI Big Bore Bart:Thanks for the heads up.I need a little clarification of terms."Then look through the pin hole at the alignment". Is that the oil hole or...?
Thanks
PS Voltar in a previous life I designed pneumatic actuators for damper systems and in those instances pistons and valves were not bed follows.

Thanks again for the collective guidance.


:-) :-)

I work on stuff designed by engineers........ I know how that goes. Haha

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PostPosted: Mon Nov 24, 2014 1:54 pm 
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Location: Alberta
After the shot is fired, pull the handle away from the tube, you should feel it go over center. Turn the gun so handle is up and it should sit about an inch away from the tube.
Minimum practical headspace for most efficient compression per pump stroke.

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PostPosted: Mon Nov 24, 2014 7:54 pm 
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Joined: Fri Sep 02, 2005 8:16 pm
Posts: 136
Location: CANADA
HI Voltar:"Minimum practical headspace"yes that is exactly what I was trying to get the answer for.My sense it is an experiential thing so I was after the advice with the most experience behind it.
I graduated as a Mech Eng then completed an apprenticeship in a Red Seal trade and that was a lot of years ago.The mix allows me to fix old pinball machines and poorly designed English sport cars.
The advice I get from an experienced tool and die guy is as valuable to me as advice from an experienced engineer.

Thanks for the input.


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