Author Topic: Discovery valve porting questions (Read 9069 times))

ChrisR10 · « **Reply #20 on:** April 12, 2016, 10:03:09 PM »

Quote from: rsterne on April 12, 2016, 09:58:03 PM

Yes, that is a good extension for the valve if you use a PRod gauge block....

Bob

Thanks Bob, any special way to seal the gauge to the adapter and adapter to the gauge block?

Rivers3Plinker · « **Reply #21 on:** April 13, 2016, 11:07:51 AM »

Quote from: ChrisR10 on April 12, 2016, 10:03:09 PM

Quote from: rsterne on April 12, 2016, 09:58:03 PM
Yes, that is a good extension for the valve if you use a PRod gauge block....

Bob

Thanks Bob, any special way to seal the gauge to the adapter and adapter to the gauge block?

That's the same one I ordered and I was simply planning on using teflon tape like any other NPT fitting. I suppose you could use the paste but I don't like the mess and figured it might get someplace I don't want it.

Iamscotticus · « **Reply #22 on:** April 13, 2016, 11:18:55 AM »

I have a problem with tape and HP applications.
The two just don't seem right together.

nervoustrigger · « **Reply #23 on:** April 13, 2016, 12:04:52 PM »

For tapered fittings (i.e. the T in NPT), PTFE tape works well.

In non-tapered threads, don't bother. That requires an O-ring or other type of compressible seal. A notable exception to that is the metal-to-metal seal at the bottom of (many) burst disks. That obviously requires tight tolerances, smoothness of mating surfaces, etc. which is why you want to be careful about over tightening a burst disk because it can gouge the seat and make sealing a problem in the event it ruptures and you need to replace it.

For obstinate applications, they make liquid thread sealants much like thread locker (and yes, conventional thread locker may work fine) but I like to treat those as a last resort.

MichaelM · « **Reply #24 on:** April 13, 2016, 02:18:19 PM »

Quote from: Rivers3Plinker on April 12, 2016, 09:29:37 PM

Quote from: MichaelM on April 11, 2016, 02:41:30 PM
I actually just finished my SSG setup last night for the double... Now my results my not be typical because when I first got the gun Lloyd had done extensive work on it, hogged out valve, Completely hogged out gauge block, Heavy spring and a Bstaley stack, and a .138 transferport.. he had it shooting an average of 38 shots at 26.3 fpe with 14.3gr pellets or a 1.36fpe/cuin eff on a 2k to 1300psi fill... it took me a few days to try to get it set and tweaked with a ssg to copy as closely to his power lvls to compare apples to apples...

I was FINALLY able to get close to his results by using a lighter spring in the SSG (I think its the .039 spring that bob recommended for 2200 fills in the disco..) and changing to a tiny .120 transfer port.... lol I was only able to gain 2 shots over that range with more or less the same fpe lol think it came out to 1.42fpe/cuin eff...

guess what I am trying to get at... unless your wanting to make significant more power then 30 fpe or so... you really dont need to do a lot of valve work and the stock valve and transfer port should be plenty unless your wanting to go monster power lvls ... and smaller might actually be a bit more efficient

Interesting....Thanks Mike. So your combo is a heavily modded valve but then a reduced transfer port to improve efficiency. The transfer port is the restriction, not the valve. BUT... you are shooting a 14.3 grain round and I'm looking to go with 18 or 21.

I think I'm going to start by modifying another valve body and go with mild mods to the exhaust port. Mod for the screws for safety, stick with stock port size but angle drill the port. Leave the throat alone and poppet too. Get some shot strings and experiment with fill pressures.

I would bet that if did nothing but load up some 18.1 into the gun and shot another string I would get REAL close to if not over 30 fpe and probably pick up a couple shots as the 18.1 grainers tend to be more efficient FPE wise.. I unfortunately don't have any on hand to test or I would.....

rsterne · « **Reply #25 on:** April 13, 2016, 07:03:03 PM »

I use Teflon "Gas Fitters" tape.... the yellow one that is thicker than the white....

Bob

Iamscotticus · « **Reply #26 on:** April 13, 2016, 11:56:20 PM »

Quote from: rsterne on April 13, 2016, 07:03:03 PM

I use Teflon "Gas Fitters" tape.... the yellow one that is thicker than the white....

Bob

Thats more like it.

Rivers3Plinker · « **Reply #27 on:** April 19, 2016, 10:43:12 AM »

I bought two extra valve assemblies from Crosman just in case I damaged one or wanted a backup for a different approach. I spent an hour or so last night working on enlarging and tapping the holes for larger screws but I should have just stayed out of the garage. I trashed both of them hamfisted drilling the holes crooked in both and stripped the threads trying to tap another. I still have the OEM valve and might just put it back together as-is and forget about the idea.

Has anyone had any experience or tried this high flow valve from bakerairguns?
I've inquired about it through their site.

https://www.bakerairguns.com/product/max-flow-valve-for-benjamin-discovery/

Rivers3Plinker · « **Reply #28 on:** April 25, 2016, 07:00:05 PM »

Well - Disco is back together these mods:

Midly ported stock valve - exhaust port 20 degree ( approximately ) angle ground with carbide dremel bit followed up with diamond coated ball shape bit on the turn and then polished with paracord and Mothers aluminum polish. I do this by running the cord through the port and out the throat of the valve and apply mothers to the cord on top. I pull it in and out of the port using the cord like a polishing rope of sorts. It mostly takes off any sharp edges but also polishes the surface nicely
Exhaust port diameter same as stock
Drilled out the B&M transfer port bushing to .156. I mic'd the stock bushing and it was slightly smaller than stock but I can't recall numbers
Contoured the poppet valve a bit rounding the sharp edges
New gauge and riser with Prod gauge block. Gave me same pressure numbers as my Mark4 hand pump gauge and is actually a useful gauge.
Drilled and tapped for 10-32 screws. One isn't as straight as I would like but no alignment issues or anything I see as impacted by it
Trakar hammer spring

I put 2200 lbs in it and it sighted in at 45 yards. First few shots were about 10" higher than before hitting my trap harder and faster than I recall.
Regardless of any increase in power, which I have yet to determine is...... it groups a lot better! I was very pleased with groups.
I shot it down to 1600psi before refilling and no change in POI. I want to say 16 shots or so, but did not count.
Without pics or charts this post is kind of lame but I'm happy with my Disco for now.
Chronny testing next weekend for sure. Going to have a gun fun day with my brother and his Mrod and get numbers and shot strings for both guns. We'll also be tag team pesting starlings which should be a blast. Bringing lots of ammo and my pump.

MichaelM · « **Reply #29 on:** April 26, 2016, 12:11:18 AM »

Very cool man! want to see what your strings are looking like now!... I would post my shot strings with the restricted transfer port but photobucket seems to be on the fritz right now lol

Rivers3Plinker · « **Reply #30 on:** April 29, 2016, 11:23:12 AM »

I ordered and received the Boss valve from Baker Airguns and made a few observations.
Exhaust port size nearly same as stock. The port is angled and machined as a new part this way, not a straight port modified with angle drilling. The poppet is nicely profiled for air flow at the throat and made from brass and polymer. I don't have a bore gauge or any way to measure the throat easily so I didn't attempt.
My plan is to get numbers and shot strings from my DIY modified valve and then swap out for the Boss and do the same.
The outcome will likely be higher FPE peak numbers, a peakier string, and lower shot count / more rapid air consumption with the Boss valve.

Matt15 · « **Reply #31 on:** April 29, 2016, 02:03:28 PM »

Looking forward to seeing your numbers!!!

Rivers3Plinker · « **Reply #32 on:** May 01, 2016, 09:10:32 PM »

ROUGH day today. So we shot my brothers box stock .25 Synrod. He was getting numbers in the 750's give or take 10fps for about 30 shots and was dead-nuts accurate. At shot 31 they started POI high and left and it was making the telltale PRRRRT sound dumping air from the yo-yo effect. What a fun gun to shoot!
I was next. filled to 2200lbs and managed 6 shots all in the 850 range before "PFFFFFFT!" my gun discharged all it's air and wouldn't pump anymore. Tear down revealed the poppet head cracked and came apart! So I reassembled with my newly purchased boss valve.
It wouldn't hold pressure either! I pulled the bolt and dry fired it, tried pumping it with the bolt open and closed. I couldn't get it to take a pump no matter what I tried. Tore it all apart again, removed the Boss valve and put mine back in the gun with a new poppet. While installing my 1st gen Mrod / Challenger trigger I flipped the sear over the wrong way and while tightening the trigger group screws, I broke the dang sear. I was DONE for the the day and irritated. My numbers with my home ported valve were around 840 to 860 for the few shots I managed to chronny. What a frustrating day. I put all the parts in a bag and grabbed a beer afterwards.

I will be back. I cannot figure out why the Boss valve poppet would not seat or seal to the throat. I will probably try lapping it with compound and and use a drill to see if I can get it to seal. I'll be ordering another sear Monday.
FWIW I was nailing shots from 50yds while I was testing. It was working great with tight groups up until the poppet failed. Major bummer.

sshewins · « **Reply #33 on:** May 06, 2016, 12:18:33 AM »

Ouch! That not right. Hopefully it'll be something simple and a quick fix.

2K1TJ · « **Reply #34 on:** May 07, 2016, 02:53:49 PM »

Interesting read. I like the tip about using the paracord and Mother's. I'll have to remember that. Sorry about your crappy luck with the poppets...can't wait to hear some numbers when you get it fixed.

Rivers3Plinker · « **Reply #35 on:** May 10, 2016, 03:07:21 PM »

New sear in the mail from Crosman. I put the trigger back together and while I was in there, a spring shot out of it across the room.
I found it but wasn't able to quickly identify where it was supposed to go.
After some quick Google searching, I learned it was the dreaded "lawyer spring" so I left it out.
Trigger is lighter than before now. Feels pretty good to me.

Rifle is back together and holds air. Everything looks good so far but no shots yet.
I picked up a camera tripod from Amazon for my Chrony so I'm ready to get numbers now.
We will have cool whether this weekend ( Michigan ).

Rivers3Plinker · « **Reply #36 on:** May 24, 2016, 11:51:55 AM »

OK I finally had some time to shoot last Friday but didn't have time to play with the chronny.
What I can say is with a mildly ported stock valve, Prod gauge port, Prod hammer weight, and TRAKAR spring in the gun:
Filling to 2000psi shooting 18.1 grain JSB

First 3 to 4 shots are much higher POI until the gun reaches 1800psi
Settles down at that pressure and shoots quarter size groups at about 45 yards resting on the hand rail of my deck. No bag or sled or bipod.
Averages about 12 to 14 shots grouping well until pressure reaches about 1200psi beyond which point they start dropping very fast

I guess this is an expected result based on mods and lack of SSG. I desperately need one for the gun now to increase the shot count with this valve. I "think" my FPS is in the 850 range which is where it was last time I chronographed it with this same valve using only a different poppet that had the back profiled for more flow ( until it broke ). I don't believe this was making a huge difference here.

Truth be told I now understand why it's probably best to leave the gun at stock power level with a stock valve to get the most shots and most consistent POI per fill. Otherwise I'm looking at charging it to 1800 and not even getting 2 magazines of ammo through it before I have to fill again. That is my next plan - to put the stock valve back in the gun.

I am now debating a .25 cal Marauder rather than trying to take the Disco someplace it was never designed to go.

Iamscotticus · « **Reply #37 on:** May 25, 2016, 12:03:31 PM »

Quote from: Rivers3Plinker on May 24, 2016, 11:51:55 AM

I am now debating a .25 cal Marauder rather than trying to take the Disco someplace it was never designed to go.

This is best choice. You then have another gun to mod.

rsterne · « **Reply #38 on:** May 25, 2016, 12:19:52 PM »

Quote

rather than trying to take the Disco someplace it was never designed to go.

You see I'm just the opposite.... I love the Disco, and trying to push it to ridiculous power levels.... I have managed to get over 175 FPE in 9mm with one, at 3000 psi, with the appropriate valve and safety mods.... but it's not for someone who doesn't love to tinker, or know what they are doing....

Bob

Rivers3Plinker · « **Reply #39 on:** May 25, 2016, 02:52:30 PM »

Quote from: rsterne on May 25, 2016, 12:19:52 PM

Quote
rather than trying to take the Disco someplace it was never designed to go.

You see I'm just the opposite.... I love the Disco, and trying to push it to ridiculous power levels.... I have managed to get over 175 FPE in 9mm with one, at 3000 psi, with the appropriate valve and safety mods.... but it's not for someone who doesn't love to tinker, or know what they are doing....

Bob

Yeah see that's impressive. Is that gun single tube and you fill it with a hand pump ; )

I've had my fill of tinkering lately and I just want to shoot now.
I have a .25 cal Mrod, an extra mag, and a couple tins of JSB kings in the cart at AGD.
Have not pulled trigger yet.

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Discovery valve porting questions

Author Topic: Discovery valve porting questions (Read 9069 times))