Does a VM need liquid? - Page 2

Schmitti · 06-11-2009, 08:32 PM

Curt.. STOP!!!!!!

Are you running with the tank horizontal under the barrel? If so you are probably getting liquid into the gun/valve.

YOur best bet is either set it up to run on liquid (it's easy to do) or bottomline it and set it up to run on gas.... if you set it up for gas throw a reg on the front, it just makes it that much easier to adjust the velocity.

E

russc · 06-11-2009, 08:45 PM

Quote:

Originally Posted by Darth Sparky

I think that only matters if the upper transfer port is drilled out as well. Mine is slightly larger than 3/16" (maybe a metric size?). I believe that a valve port larger than that would be useless. It may also reduce the blow back flow.

David

I gained about 40 fps on HPA by drilling out the valve without touching the body transfer port.

Darth Sparky · 06-11-2009, 09:08 PM

Which transfer port? If it is the upper one then you have to remove a grub screw in the top of the marker. You will need to tap the new hole and put in a new grub screw if you do this.

If it is the lower transfer port then you need to remove the ASA.

Darth Sparky · 06-11-2009, 09:10 PM

Quote:

Originally Posted by russc

I gained about 40 fps on HPA by drilling out the valve without touching the body transfer port.

That doesn't make sense to me unless the port was already larger than your valve hole.

russc · 06-11-2009, 09:10 PM

I didn't touch the transfer ports, only the valve hole. It worked, that's all I'm going on.

Darth Sparky · 06-11-2009, 09:19 PM

Quote:

Originally Posted by russc

I didn't touch the transfer ports, only the valve hole. It worked, that's all I'm going on.

I understand. Perhaps the port being larger than 3/16" for me meant that going larger than 3/16" on the valve port gave you that extra flow. It wasn't a tiny difference and given that the area of a circle is pi times square of the radius even small increases in the radius of the hole have a large impact.

I wonder if it is important to have the lower transfer port larger than the upper one in a blow back marker. I am thinking that if they were the same or the upper one larger that there would be no pressure left to recock the marker.

Sgt Hollywood · 06-11-2009, 09:35 PM

Valve port 3/16 is the sweet spot for decent improvement.

It does sound like the main spring is wasted and not hammering the valve enough. Was it left in the cocked position? Try shimming it out a bit and see if you see improvement, might just help isolate the issue.

HurtCow · 06-11-2009, 10:24 PM

Quote:

Originally Posted by Schmitti

Curt.. STOP!!!!!!

Are you running with the tank horizontal under the barrel? If so you are probably getting liquid into the gun/valve.

YOur best bet is either set it up to run on liquid (it's easy to do) or bottomline it and set it up to run on gas.... if you set it up for gas throw a reg on the front, it just makes it that much easier to adjust the velocity.

E

Chill Eric.

It's backbottle, angled down. So no liquid.

infamoussmiley · 06-11-2009, 10:34 PM

check to see if the allen screw in the bolt is stripped out and when it goes forward, the screw flies forward plugging the hole. Also check that brass valve stem guide in the valve. Make sure it is not backing its way out and it is tight. also check the hammer oring to make sure its not a chris mader hammer oring or a tank oring or that its mushroomed.

smiley

Anonymous Coward · 06-11-2009, 11:00 PM

170'ish?

My guess is a to short or to long ASA depression pin or short valve pin in the tank. Below 200 fps, that's the first thing I always look at with CO2. Or that VM was setup for liquid and the valve spring is to strong. A small dowel behind the main spring should be enough to tell you if the issue is the main spring.

Of coarse there is a slew of other things to check out that can apply to any blow back and if I ran down them, it would only sound insulting.

06-11-2009, 09:35 PM	#17 (permalink)
Sgt Hollywood ΜΟΛΩΝ ΛΑΒΕ Join Date: Mar 2009 Location: NYC	Valve port 3/16 is the sweet spot for decent improvement. It does sound like the main spring is wasted and not hammering the valve enough. Was it left in the cocked position? Try shimming it out a bit and see if you see improvement, might just help isolate the issue. __________________ Sgt. Hollywood's feedback Mini collection Old School VM68 Mag with PPS Stab, dual bottle (rear and slant. Ported valve and Starfire Bolt (alum), tweaked springs & Lapco Cocker adapter. Pneumatic Design Storm Oddball marker but fairly accurate. Phantom 6",11 & 14"" DanW .45 Grips SC hori feed now VSC, Shoed up. PGP Blinging, Classic AutoMag (mini) "Tactical" custom, Trracer Rifle in the works, 2k+VF WGP cocker, 2 Trilly Pump "Sniper" conversions, 3 Trracers

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06-11-2009, 08:32 PM	#11 (permalink)
Schmitti Red=Moderator Join Date: Apr 2006 Location: Schen. NY	Curt.. STOP!!!!!! Are you running with the tank horizontal under the barrel? If so you are probably getting liquid into the gun/valve. YOur best bet is either set it up to run on liquid (it's easy to do) or bottomline it and set it up to run on gas.... if you set it up for gas throw a reg on the front, it just makes it that much easier to adjust the velocity. E

06-11-2009, 09:08 PM	#13 (permalink)
Darth Sparky Newbie Join Date: Jun 2009 Location: Calgary	Which transfer port? If it is the upper one then you have to remove a grub screw in the top of the marker. You will need to tap the new hole and put in a new grub screw if you do this. If it is the lower transfer port then you need to remove the ASA.

06-11-2009, 10:34 PM	#19 (permalink)
infamoussmiley . Join Date: May 2006	check to see if the allen screw in the bolt is stripped out and when it goes forward, the screw flies forward plugging the hole. Also check that brass valve stem guide in the valve. Make sure it is not backing its way out and it is tight. also check the hammer oring to make sure its not a chris mader hammer oring or a tank oring or that its mushroomed. smiley

06-11-2009, 11:00 PM	#20 (permalink)
Anonymous Coward Active Member Join Date: Jul 2007	170'ish? My guess is a to short or to long ASA depression pin or short valve pin in the tank. Below 200 fps, that's the first thing I always look at with CO2. Or that VM was setup for liquid and the valve spring is to strong. A small dowel behind the main spring should be enough to tell you if the issue is the main spring. Of coarse there is a slew of other things to check out that can apply to any blow back and if I ran down them, it would only sound insulting.