Tore deeper into the Flying Dragon XS 60C PCP today - not quite done....

[Ribbonstone]

The TKO for the XS60C PCP should be the middle one in the below picture. Same one that can be threaded 1/2-20 (but for the FDPCP would be grub screwed rather than threaded).  Considerably larger in diameter than the  Discovery version at top.

[RayK]

I took the FD out to shoot yesterday.  Sadly, the 3 o-ring BHB is not doing the job.  It needs more thickness, but maybe 4 o-rings is too much.

I had the hammer spring preload set to minimum and the trigger group in the middle of its range.  The shot string was stricktly decreasing which means there is still too much hammer energy for the fill pressure (and I started at 1700 psi to see the top of the shot string).

I'll add another o-ring and see if I can get it to shoot.  If not, i'll have to try the underspec o-ring from Harbor Freight and see if that hits the magic thickness for the buffer.  I really wish the FD had an adjustable stiker like the Marauder.  Getting the buffer thickness right in the FD is going to be a challenge.

Ray

[avator]

I saw where Rsterne sanded the thickness of the orings and also used shims between them.

[Oldblades]

After reading of a valve mod and following Rsternes in depth thread on the FDPCP, I found a way that you can set the preload on the valve spring pretty easily. Keep in mind that I'm brand new at this game, but a hopelessy habitual tinkerer.

I slipped a 8-32(I think?) 1" machine screw through the bottom hole and then ran a nut on it to hold it in place.
Then ran a second nut with a washer that will fit inside the 'shelf' that the OEM washer sits on. That gives the spring a shaft to keep it from canting as a bonus.
Then just put a tiny skin of blue loctite in the travel area of the adjusting nut. You can then use a small scewdriver to turn the nut up or down to tighten or loosen the valve spring.
 Still messing with it but its looking good so far.

So if you want to try tightening the valve spring a fuzz, it may help you out. If not, there is no alteration to the valve body needed and you can just return it back the way it was. I will say that it doesnt take much up or down from factory to make quite a difference.

[Yarp]

After reading of a valve mod and following Rsternes in depth thread on the FDPCP, I found a way that you can set the preload on the valve spring pretty easily. Keep in mind that I'm brand new at this game, but a hopelessy habitual tinkerer.

I slipped a 8-32(I think?) 1" machine screw through the bottom hole and then ran a nut on it to hold it in place.
Then ran a second nut with a washer that will fit inside the 'shelf' that the OEM washer sits on. That gives the spring a shaft to keep it from canting as a bonus.
Then just put a tiny skin of blue loctite in the travel area of the adjusting nut. You can then use a small scewdriver to turn the nut up or down to tighten or loosen the valve spring.
 Still messing with it but its looking good so far.

So if you want to try tightening the valve spring a fuzz, it may help you out. If not, there is no alteration to the valve body needed and you can just return it back the way it was. I will say that it doesnt take much up or down from factory to make quite a difference.

A picture of this would be good to see.

[moorepower]

There are lots of photos of these. He is making an adjustable stop for the valve in the valve body.

[RayK]

That is an idea I had not considered.

So is it a poppet stop or does it change the spring preload on the poppet return spring?

If you have a picture or a link to a picture, that would help a lot.

I'm a fan of stiffer valve return springs since they tend to give longer, flatter shot strings when not using the BHB o-rings.

Ray

[Yarp]

There are lots of photos of these. He is making an adjustable stop for the valve in the valve body.

Bear in mind that I'm just getting past taking apart and modding a 2240 and three FDPCPs. Screwing around with a valve is one or two steps ahead.......I've looked but haven't seen a shot of anyone's rendition of an "adjustable stop" for the valve in the valve body - Could you point me in the right direction?

Thanks either way.

[moorepower]

I have seen both for spring pressure and poppet stop. They have a hole for a screw in the end of the valve "schroud"  McMaster Carr has round shims that could be stacked, in many thicknesses. It is quicker to get the valve out and shim, than to take the valve out.

[Oldblades]

Mine is not a poppet stop, but simply makes the springs preload adjustable.
I'm busting my chops today trying to get a porch roof buttoned up before a T storm tomorrow. I have a spare valve that Mike sent me and I'll do a duplicate mockup for photos later on tonight or in the morning.

[RayK]

Thanks OldBlades!  That will be great!

Ray

[Oldblades]

Uf-Dah. Weatherman says 'chance of rain, some may be heavy' at around 3pm. this morning about 7:30. Think to myself, Great that gives me time to pull the roof overhang out and get it buttoned back up. Instead I get the overhang tore out with 12' of the interior ceilings sheetrock exposed and get torrential rain at 11 am. What a mess.
So much for believing the forecast (once again) 

I just went out to the shop and put the extra valve together. Like I said, its right in my wheelhouse as being 'caveman simple'. Measured the pieces and they are a 12-24 x 1" machine screw, 2 nuts, and a 1/2" flat washer. One thing I might suggest if any7one does this, is to take the threads off of the end of the unused portion of the screw. Probably help from getting the spring coils dragging on the threads. Other than that, it works like a champ.

 

[Yarp]

Uf-Dah. Weatherman says 'chance of rain, some may be heavy' at around 3pm. this morning about 7:30. Think to myself, Great that gives me time to pull the soffit out and get it buttoned back up. Instead I get the soffit tore out with 12' of the interior ceilings sheetrock exposed and get torrential rain at 11 am. What a mess.
So much for believing the forecast (once again) 

Hanging rock makes you stronger!
...Used to live up in Anoka. The weather there is as unpredictable as it is in the high mountains.
Still have Uf-Dah on the tip of my tongue, but no one down here in FL has the slightest idea what that means.