Updated valve mod how to...

Updated valve mod how to...

Joined: June 11th, 2002, 12:12 pm

April 22nd, 2005, 5:25 pm #1

To get the valve apart put it in a vice. Use a small pipe wrench or channel locks on the cap. Does not need to look pretty on the outside. Like most things in the world it's what's inside that counts.

Parts that help a great deal are.
1- Increase the volume.

Pic of the front of the valve cap. I have cut some of the threads off but left more than half for strength.



That's 25/64ths on the bit. I drilled down about 1/4" then polished it inside.



2- Drill the exhaust port.
The port hole drilled in the valve should be the same size as the ID of the breech seal used. 11/64ths or a #19 drill bit seems to be near the sweet spot for the .22 caliber. The intake port may be drilled also but with the increased volume it should not make much of a difference for the .22 guns. Larger calibers can benefit from a larger intake especially if they are tube bulked.



3-Change port angle
Use a dremmel to ease the port angle. You can see in the pic that the job was not quite completed as the angle should have been brought all the way to the top of the valves exhaust port. But you get the idea. Then polish it up with a thin strip of 600 grit sandpaper taped to a the back end of a small drill bit or similar item and installed on the dremmel shaft. That is polished the area just dremmelled out. Also polished the other area marked on the diagram. If this one is messed up, bottom arrow, the valve will leak constantly. Could be left alone without losing much at all but the more polished everything is the smoother the flow.




4- Lighter spring.
Here are some lighter springs. The spring should be about 1/8 to 1/4" longer because the volume in the valve was increased by drilling near that far into the cap. The spring will actually close the valve even if it is very light but gas can be wasted before it closes. I use one that's about half as strong. To light a spring can cause damage to the tube and valve. Especially when combined with a heavy hammer spring. I Have used two springs, slid together sideways then installed to get the strength when a single could not be found. Pic also contains dremmel tools, stock valve and junk valve body used later on when drilling the tube for safety screws.




5- Cut off the piercing pin if your gun is bulked.
The above picture also shows before and after pics of the stem with and without piercing pin. The metal is hard and the best way I have found to cut it is with the dremmel and a thin cut off disc. CAUTION cut a little at a time and let it cool in between or drip water on it so the heat generated will not melt the seal. The stem can be shaped also but it's easy to mess the seal up cuz the stem gets hot when you are working on it. Then chuck what is left of the stem up in a drill and use a file or sandpaper as in step two to round the sharp edges and polish the rest. Take your time because to much pressure on the brass can make it spin on the shaft then it's hard to shape and may not seal well. The bottom pin has had the shaft shaped for better flow the seal has been taken off to show you what it looks like.



SAFETY MOD GOES WITH THE VALVE MOD. Drill a couple of holes through the tube even with the exhaust port. I put my set screws on the sides of the tube which I tapped out to match the screws. Remove the burrs from inside the tube install the valve, mark it, and drill slightly into it. There are less burrs if an old valve body is installed in the tube before it is drilled. You can see the set screw just above the safety. Now your face will not wear the valve when you pull the trigger on your beefed out gun. More on this mod later.





Put it all back together and it is done. I use the blue lock tight on the cap most of the time although have gone without with no ill effects.

I used to have a life. But now I have the forum. I am a sick man?

Last edited by Biohazardman on April 23rd, 2005, 5:24 am, edited 1 time in total.
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Joined: July 29th, 2003, 7:55 pm

April 22nd, 2005, 5:49 pm #2

....You are a sick man without a doubt - as evidenced by yet another excellent Bio-Tech tutorial....! - HV
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Joined: December 15th, 2003, 2:24 am

April 22nd, 2005, 6:47 pm #3

It's all good info for modding a 1377 air valve too. Keep up the good work and May The Force Be With You.
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Joined: May 10th, 2004, 4:27 am

April 22nd, 2005, 8:31 pm #4

To get the valve apart put it in a vice. Use a small pipe wrench or channel locks on the cap. Does not need to look pretty on the outside. Like most things in the world it's what's inside that counts.

Parts that help a great deal are.
1- Increase the volume.

Pic of the front of the valve cap. I have cut some of the threads off but left more than half for strength.



That's 25/64ths on the bit. I drilled down about 1/4" then polished it inside.



2- Drill the exhaust port.
The port hole drilled in the valve should be the same size as the ID of the breech seal used. 11/64ths or a #19 drill bit seems to be near the sweet spot for the .22 caliber. The intake port may be drilled also but with the increased volume it should not make much of a difference for the .22 guns. Larger calibers can benefit from a larger intake especially if they are tube bulked.



3-Change port angle
Use a dremmel to ease the port angle. You can see in the pic that the job was not quite completed as the angle should have been brought all the way to the top of the valves exhaust port. But you get the idea. Then polish it up with a thin strip of 600 grit sandpaper taped to a the back end of a small drill bit or similar item and installed on the dremmel shaft. That is polished the area just dremmelled out. Also polished the other area marked on the diagram. If this one is messed up, bottom arrow, the valve will leak constantly. Could be left alone without losing much at all but the more polished everything is the smoother the flow.




4- Lighter spring.
Here are some lighter springs. The spring should be about 1/8 to 1/4" longer because the volume in the valve was increased by drilling near that far into the cap. The spring will actually close the valve even if it is very light but gas can be wasted before it closes. I use one that's about half as strong. To light a spring can cause damage to the tube and valve. Especially when combined with a heavy hammer spring. I Have used two springs, slid together sideways then installed to get the strength when a single could not be found. Pic also contains dremmel tools, stock valve and junk valve body used later on when drilling the tube for safety screws.




5- Cut off the piercing pin if your gun is bulked.
The above picture also shows before and after pics of the stem with and without piercing pin. The metal is hard and the best way I have found to cut it is with the dremmel and a thin cut off disc. CAUTION cut a little at a time and let it cool in between or drip water on it so the heat generated will not melt the seal. The stem can be shaped also but it's easy to mess the seal up cuz the stem gets hot when you are working on it. Then chuck what is left of the stem up in a drill and use a file or sandpaper as in step two to round the sharp edges and polish the rest. Take your time because to much pressure on the brass can make it spin on the shaft then it's hard to shape and may not seal well. The bottom pin has had the shaft shaped for better flow the seal has been taken off to show you what it looks like.



SAFETY MOD GOES WITH THE VALVE MOD. Drill a couple of holes through the tube even with the exhaust port. I put my set screws on the sides of the tube which I tapped out to match the screws. Remove the burrs from inside the tube install the valve, mark it, and drill slightly into it. There are less burrs if an old valve body is installed in the tube before it is drilled. You can see the set screw just above the safety. Now your face will not wear the valve when you pull the trigger on your beefed out gun. More on this mod later.





Put it all back together and it is done. I use the blue lock tight on the cap most of the time although have gone without with no ill effects.

I used to have a life. But now I have the forum. I am a sick man?

My father prefers the flatter trajectory....I need to rework the 2250 I bought him for squirrel whacking...

I have to order a 1750 or 1760 barrel and bolt, but am curious as to what you recommend for valve mods/port size, etc.

Thx!


"Silence is Golden!"

-PR
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Joined: June 11th, 2002, 12:12 pm

April 23rd, 2005, 1:20 am #5

small as pellet damage will occur otherwise. Have only done one and did not tune it to much as it was over 700fps easy. Probly can take the port up a sixty forth of an inch or so. Does not sound like much but doesn't take much when you are already over gassing the gun in the .177. You want a looonng barrel too to make use of all that gas. On the pistols I usually put in a lighter hammer spring very little fps loss and more shots.

I used to have a life. But now I have the forum. I am a sick man?

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Joined: June 1st, 2004, 10:06 pm

April 23rd, 2005, 2:18 am #6


in 177..............................>

1750MASTER

For custom airgun work and sales.
http://www.mountainaircustomairguns.com/
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Joined: June 11th, 2002, 12:12 pm

April 23rd, 2005, 2:39 am #7

where's the end of that thing anyway?



I used to have a life. But now I have the forum. I am a sick man?

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Joined: June 1st, 2004, 10:06 pm

April 23rd, 2005, 3:10 am #8

nt

1750MASTER

For custom airgun work and sales.
http://www.mountainaircustomairguns.com/
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Joined: May 10th, 2004, 4:27 am

April 23rd, 2005, 3:43 am #9

small as pellet damage will occur otherwise. Have only done one and did not tune it to much as it was over 700fps easy. Probly can take the port up a sixty forth of an inch or so. Does not sound like much but doesn't take much when you are already over gassing the gun in the .177. You want a looonng barrel too to make use of all that gas. On the pistols I usually put in a lighter hammer spring very little fps loss and more shots.

I used to have a life. But now I have the forum. I am a sick man?

.

"Silence is Golden!"

-PR
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Joined: December 18th, 2004, 6:21 pm

April 23rd, 2005, 4:15 am #10

To get the valve apart put it in a vice. Use a small pipe wrench or channel locks on the cap. Does not need to look pretty on the outside. Like most things in the world it's what's inside that counts.

Parts that help a great deal are.
1- Increase the volume.

Pic of the front of the valve cap. I have cut some of the threads off but left more than half for strength.



That's 25/64ths on the bit. I drilled down about 1/4" then polished it inside.



2- Drill the exhaust port.
The port hole drilled in the valve should be the same size as the ID of the breech seal used. 11/64ths or a #19 drill bit seems to be near the sweet spot for the .22 caliber. The intake port may be drilled also but with the increased volume it should not make much of a difference for the .22 guns. Larger calibers can benefit from a larger intake especially if they are tube bulked.



3-Change port angle
Use a dremmel to ease the port angle. You can see in the pic that the job was not quite completed as the angle should have been brought all the way to the top of the valves exhaust port. But you get the idea. Then polish it up with a thin strip of 600 grit sandpaper taped to a the back end of a small drill bit or similar item and installed on the dremmel shaft. That is polished the area just dremmelled out. Also polished the other area marked on the diagram. If this one is messed up, bottom arrow, the valve will leak constantly. Could be left alone without losing much at all but the more polished everything is the smoother the flow.




4- Lighter spring.
Here are some lighter springs. The spring should be about 1/8 to 1/4" longer because the volume in the valve was increased by drilling near that far into the cap. The spring will actually close the valve even if it is very light but gas can be wasted before it closes. I use one that's about half as strong. To light a spring can cause damage to the tube and valve. Especially when combined with a heavy hammer spring. I Have used two springs, slid together sideways then installed to get the strength when a single could not be found. Pic also contains dremmel tools, stock valve and junk valve body used later on when drilling the tube for safety screws.




5- Cut off the piercing pin if your gun is bulked.
The above picture also shows before and after pics of the stem with and without piercing pin. The metal is hard and the best way I have found to cut it is with the dremmel and a thin cut off disc. CAUTION cut a little at a time and let it cool in between or drip water on it so the heat generated will not melt the seal. The stem can be shaped also but it's easy to mess the seal up cuz the stem gets hot when you are working on it. Then chuck what is left of the stem up in a drill and use a file or sandpaper as in step two to round the sharp edges and polish the rest. Take your time because to much pressure on the brass can make it spin on the shaft then it's hard to shape and may not seal well. The bottom pin has had the shaft shaped for better flow the seal has been taken off to show you what it looks like.



SAFETY MOD GOES WITH THE VALVE MOD. Drill a couple of holes through the tube even with the exhaust port. I put my set screws on the sides of the tube which I tapped out to match the screws. Remove the burrs from inside the tube install the valve, mark it, and drill slightly into it. There are less burrs if an old valve body is installed in the tube before it is drilled. You can see the set screw just above the safety. Now your face will not wear the valve when you pull the trigger on your beefed out gun. More on this mod later.





Put it all back together and it is done. I use the blue lock tight on the cap most of the time although have gone without with no ill effects.

I used to have a life. But now I have the forum. I am a sick man?

How do you pierce the cart without the piercing pin?
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