Tale of THREE BRods - .25, .30 and .357 Completed, Page 19 !

[rsterne]

Today I pulled out the Iso-Damp bumper I had, and substituted a #210 90D O-ring.... I did this because ANYONE can find one of those.... I set the striker FLUSH with the end of the hammer, because then you don't need an adjustable hammer, Travis' new MDS hammer with the flat face would work fine.... The hammer I was using was still very light, at only 28 grams, and I was still running the SSG.... I measured the distance the hammer can push the valve stem with the #210 O-ring in place, and even pushing on the hammer very hard, it only pushes the valve stem 0.075".... I think this is right in the sweet spot, the valve opens plenty far enough, but you can't drive it so far that it becomes an air hog.... I haven't tried this at 2900 psi, but at 1900 psi, it is SIMPLE and works GREAT !.... There was NO change in the settings required with the 0.028" vent hole and no metering rod, the performance was identical to with the Iso-Damp....

This afternoon I put the metering rod back, with a small spring under it, as Travis suggested.... I had it small end down, and the spring was from a Crosman 13XX Safety..... It went coil-bind just before the valve stem went flush with the valve, but that is about 0.100" past where the hammer stops.... Basically there was almost no difference compared to running the valve with no rod at all, running tethered at 1900 psi.... The vent hole was still 0.028", and the peak velocity was a about 10 fps lower at zero gap on the SSG, and also at 2 turns of gap.... At 2.5 turns out, the velocity was about the same as with no rod, but the ES was a bit worse.... At 3 turns out, the velocity was actually 13 fps higher than with no rod, and the ES had increased to over 150 fps over 4 shots.... Not only did I not see an increase in the adjustability of the valve between maximum and the cliff, I was seeing greater instability in velocity than without the rod at all.... I was not at all happy with the way it was performing with the metering rod in place, so I took it back out....

For the next tests, I increased the diameter of the vent hole to 0.0345" (ie between 0.034-0.035"), which TRIPLES the area of the original 0.020 hole in the stem.... I did not use the metering rod.... With the gun once again tethered at 1900 psi, I immediately noticed both a drop in velocity, and a decrease in the report.... I tested hammer spring settings from 8 turns of preload, through zero gap on the SSG, to 4 turns of gap, where it fell off the cliff.... Here is the results, plotted on the same graph I posted yesterday....



There are a couple of things to note.... Although I didn't bother to plot it, once I added preload to the hammer spring I noticed the same high-frequency "fluttering" sound I heard yesterday, and with the larger vent hole, it was accompanied by a significant DROP in velocity.... The more preload I cranked in, the lower the velocity got, until at 8 turns of preload it was just over 900 fps.... While not a huge loss, there was no way I could get to the nearly 990 fps velocities I was getting with the same ports, at the same pressure, before I started enlarging the vent hole.... I think this is proof positive that enlarging the hole reduces the valve dwell.... I did NOT try removing the O-ring so that I could drive the valve to greater lift, I don't know if that would move the plateau up again.... but I am pretty sure that doing that would burn a lot more air.... Note that the velocity with the 0.035" vent hole actually peaked at 1/2 turn of gap on the SSG, and fell off both sides of that.... This is completely different than the way the Cothran valve was designed to work.... At 2 turns of gap, the ES had increased to over 50 fps, and at 3 turns of gap it was over 100 fps.... At 4 turns the valve had fallen off the cliff, as expected....

I then tethered the gun to my 500 cc bottle, with an 1800 psi regulated output, to check the efficiency.... I only shot two 8-shot strings, one at the maximum velocity setting of 1/2 turn of gap, and the other with 1.5 turns of gap, where the velocity was still stable.... All I was interested in was comparing the efficiency to what I had with the 0.028" vent hole.... At the higher setting, I got an average velocity of 921 fps (64.4 FPE) and an ES of 1.29 FPE/CI.... With 1 turn more gap, that dropped to 908 fps (24 fps ES at 62.6 FPE) at 1.25 FPE/CI.... Basically, I was getting the same efficiency as with the smaller vent hole, but at 5 FPE less power.... not exactly a great trade-off, IMO.... Yes, I could increase the pressure to get the power back, but I really doubt I would see enough of an increase in efficiency to make up for the decreased pressure headroom.... In this gun, in .25 cal, and at these pressures, IMO I have increased the vent hole too much....

Ohhhhhhhhhhhhh Travis.... I need a new poppet.... *LOL*....

Bob

[oldpro]

 New poppet on the way. can you run one more string with large vent hole and rod in upside down at same settings this will either confirm or make me look at another angle after long barrel testing tomorrow.

[rsterne]

Will do.... send pellets with poppet, please.... J/K.... 

Bob

[rsterne]

As Travis requested, I ran another test today, with the 0.035" vent hole and the metering rod in place, upside down, with the small spring under it.... The rest was unchanged from the previous tests, I was using a single #210 90D O-ring as a bumper, with a flush front on the 28 gr. hammer, and the SSG.... The gun was the .25 cal. version, shooting 34.2 gr. JSB King Heavies, tethered at 1900 psi.... I started at zero gap, and checked the velocity over 4 shots, at each 1/2 turn of adjustment out from there until the valve fell off the cliff....

The results were pretty much as I expected.... The rod restricted the filling of the cavity in the poppet head somewhat, and the gun acted more like it had the 0.028" vent hole without any rod in place.... The velocity was slightly less at zero preload, peaking at 1 turn of gap at 975 fps, and then declining slowly to 2 turns, after which the velocity dropped quite quickly.... It did fall in a more linear fashion over the next turn of adjustment before hitting the basement at 3.5 turns of gap.... I was not at all happy with the ES, however.... It was great while the velocity was on the plateau at 970 fps, but as soon as the velocity started to drop, the ES increased.... At an average velocity of 958 fps, at 2 turns of gap, the ES over just 4 shots was 17 fps (2%).... At 2.5 turns of gap, the average velocity was 872 fps, but over 4 shots varied between 751 - 933 fps (20%)....

I tethered the gun to my 500 cc tank, regulated as before at 1800 psi, and ran one 8-shot string to check the efficiency.... It used 210 psi, producing an average velocity of 953 fps (69 FPE) with a 17 fps ES (1.8%) over the 8 shots.... This is an efficiency of 1.25 FPE/CI, basically unchanged from previous results at that velocity....

The greatest range of adjustability I achieved during these tests was with the 0.028" vent hole and no metering rod in place.... I had a solid 20-25 fps range over which the efficiency was over 1.2 FPE/CI, coupled with a low ES.... It was the closest thing to a conventional "knee" I have been able to achieve with the Cothran valve.... The only way to really adjust the velocity remains changing the pressure.... but that setup allowed me to decrease the velocity below the normally flat plateau the Powerhouse valve displays by up to 25 fps, accompanied by a decrease in the amount of air used.... Trying to tune further below the plateau, with any of these "improvements", resulted in unstable operation and a high to unusable ES....

I am going to try the 0.035" vent version (without rod) at 2900 psi with a heavier hammer.... and also plan to do some testing with it with the .30 cal top end.... once I top up my Great White....

Bob

[Machinist]

I don't recall reading about anyone reducing the size of the force reduction piston.  I guess you would have to sleeve the piston bore and make a new piston.  I don't know how difficult this would be, or if it could be done at all.

Dons valve opens with a light hit, so some of the force reduction could be sacrificed to make the valve behave more like a conventional valve, and still not need a crazy striker spring. No?

Maybe reduce the area of the force reduction piston 30% or even 40% and see what happens.

Steve

[rsterne]

I'm sure what you are suggesting COULD be done.... the problem is in keeping everything concentric, because the poppet is mounted in one end of the valve and the force reduction piston in the other.... I can't imagine it's too easy to make them with the degree of accuracy required in a home shop.... You would have to sleeve the inside of the poppet, or make a new one, as it is the "cylinder".... Lloyd ad I have have talked about this, and it could well be the way to get some degree of self-regulation....

I just made a new "metering rod" from a piece of 3/32" brass rod 0.80" long.... The idea is to simply take up as much of the volume inside the stem as possible, without causing any restriction to the airflow between the vent hole and the chamber inside the poppet.... It is a loose fit inside the stem (0.094" rod in a 0.120" hole, so it "meters" nothing) but it's 0.10" longer than the original metering rod, so it barely fits with the poppet fully open.... I figure it can't really hurt, so I may as well try it....

Bob

[rsterne]

This evening I got a chance to do a little bit more testing.... I used the .25 cal version with the Cothran valve, with the 0.035" vent hole, but this time I put a 0.8" long piece of 3/32" brass rod inside the valve stem instead of the metering rod.... This is a loose fit, so it won't restrict the HPA entering the head of the poppet, but it will take up a lot of the volume inside the stem.... It is longer than the metering rod by 0.10", and the lenght just clears when the poppet is full open.... I also put the 51 gr. MDS hammer (with steel core) back in, so I did 2 things at once, not the best situation, but I'm running out of the 34 gr. pellets.... I tethered the gun at 1900 psi, determined where zero gap was on the SSG, and shot a couple of shots at each gap setting, increasing the gap until the velocity went over the cliff.... The velocity was pretty much stable, although the ES was poor, until I got to 4.5 turns of gap, when it started to decline, slowly at first, and then rapidly, falling over the cliff at over 6 turns of gap.... The velocity curve was quite similar to what I got with the metering rod in place with the spring, except it moved out 3 turns on gap, which would be due to the heavier hammer.... I tried one string tethered to my 500 cc bottle at 4.5 turns out, and 8 shots averaging 938 fps (67 FPE) used 220 psi of air, which is 1.16 FPE/CI, not quite as good as before....

I then tethered the gun at 2900 psi, and repeated the testing of velocity vs SSG gap.... At this higher pressure, I just nicely had enough hammer strike with the 51 gr. hammer.... I was able to max. out the velocity at 1/2 turn of gap on the SSG, just about perfect.... and the velocity was only 10 fps less than what I got in the very first tests with the valve in stock form.... With the 0.035" vent, however, there was some adjustment to the velocity before the velocity plummeted.... I didn't do enough shooting to determine what the ES was like, just a shot or two at each setting.... but it looks like the larger vent does pretty much the same thing to the curve at 2900 psi as it does at 1900 psi.... It would require a lot more testing to determine the optimum vent hole size at this higher pressure.... and the fact that I was down slightly on velocity tells me that the 0.035" hole is a bit too large.... I'm guessing that if I remove the 3/32" spacer rod, the dwell (and the velocity) will drop a bit more.... I may try that tomorrow....

Bob

[rsterne]

OK, today I used the Cothran valve with the 0.035 vent hole and no rod inside the stem.... I still like not having the rod in place, providing you have some method of completely preventing hammer bounce.... The unobstructed flow through the vent hole into the cavity in the poppet seems to provide the smoothest knee, and the tightest ES, IMO.... However, don't expect much usable range of velocity adjustment, you still need to do 95% of that with the pressure.... All the larger vent hole does is provide you the ability to approach the cliff more slowly and under more control.... The combination of a larger vent hole, and no hammer bounce, produces better efficiency.... The larger the vent hole, the shorter the valve dwell, and if you go too big, you will have to increase the pressure to get back the velocity you lose.... With the .035" vent hole, I am losing about 20 fps in the .25 cal. and about 30 fps in the .30 cal. at 1900 psi.... but gaining in efficiency....

I used my 51 gram MDS hammer with the steel core.... This additional hammer mass gave me back most of the velocity I lost when I went from the 0.028" vent hole to the 0.035" one.... This combination is the only one I have found where I can tune for both 1900 psi and 2900 psi, in both .25 and .30 cal, with just the SSG gap, and still have some gap at the higher pressure and yet get to the plateau.... I shot a few shots at each SSG gap setting with the 34.2 gr. pellets in the .25 cal at both 1900 psi and 2900, and did the same with the 50.2 gr. pellets in the .30 cal at both pressures.... Here are the results....



The .25 cal is in red, and the .30 cal is in blue.... The solid lines are at 1900 psi, and the dotted lines are at 2900 psi.... As you can see, the .30 cal requires about 1 turn less gap than the .25 cal.... At 2900 psi, you need 3 turns less gap than at 1900.... At the higher pressure I tried a couple of turns of preload (negative gap), and the gun got VERY loud (as expected) and the velocity fell off slightly.... I think that may be due to the O-ring bumper compressing with the heavy hammer strike, and kicking the hammer back slightly faster, reducing the dwell.... I also had something interesting happen with the .30 cal with 2 turns of preload.... The valve went into full auto mode, and completely dumped the 80 cc plenum, firing like a machine gun.... I would suspect that was due to removal of the metering rod, combined with too hard a hammer strike bouncing off the O-ring.... It certainly shows what can happen when you start modding a well-developed product, trying to make it do things it was never designed to do.... YOU REMOVE THE METERING ROD AT YOUR OWN RISK !!! .... Don't even think about doing that unless you have a hammer stop, and a lightweight hammer and springing system that won't bounce.... My guess is that had I still had the Iso-Damp bumper in place, its energy absorbing qualities would not have allowed this to happen....

I also tethered to my 500 cc bottle, with its output regulated to 1800 psi.... I only tested one SSG gap setting in .25 cal, and one in .30 cal, picking a velocity that was just on the low side of the plateau, at the very beginning of the knee.... The reason for that choice, was that as you approach the knee, the ES starts to increase.... This is a consistent effect with the larger vent hole, I think is what is happening is that the valve is becoming unstable when you ask it to operate where it was never designed to.... It can't make up it's mind whether to cycle properly, or to fall over the cliff.... Try as I might, I have not been able to find any combination of vent size and metering rod that produces stable velocities when you tune on the knee.... The only choice I have found, to keep a tight ES, is to tune to the point where the velocity is just starting to fall, at the bottom of the plateau.... This is in reality the same as tuning a stock valve near the top of the cliff.... the difference is that with the larger vent hole, you have less dwell, and greater efficiency, and the SSG gap adjustment is a lot less fussy.... ie it is easier to find the right spot....  Here are the results of the efficiency testing at 1800 psi....

.25 cal. 34.2 gr. JSB @ 4.5 turns of gap.... 946 fps (68 FPE) on 210 psi of air for 8 shots, which is 1.23 FPE/CI.... (should be 46 shots per fill = 3128 FPE total)....
.30 cal. 50.2 gr. JSB @ 3 turns of gap.... 909 fps (92 FPE) on 215 psi of air for 7 shots, which is 1.43 FPE/CI.... (should be 40 shots per fill = 3680 FPE total)....

Note that the shot count is projected from the pressure drop for 1 magazine, and is therefore only approximate.... It is based on a 3000 psi fill, and the 1800 psi setpoint (1200 psi of headroom).... The exact setpoint pressure and velocity and pellet used will affect the shot count, of course.... I tried the 44.8 gr. JSB .30 cal pellets, and they shot about 35 fps faster, with slightly lower efficiency.... I didn't do any testing with BBTs today.... I am pretty sure that I am going to set both BRods up regulated, with Cothran valves, in their final configurations.... Providing they prove to be accurate, it is my intention to increase the pressure slightly for the .30 cal to move the 50 gr. JSBs up closer to 950 fps.... A 2000 psi setpoint should do that nicely, trading off some efficiency and shot count to get closer to the 100 FPE mark....

Bob

[oldpro]

I also had one flutter hard and I pulled the valve today and seen the valve seat was almost destroyed this also was running with no pin. I'm looking at the parts and I believe this isn't hammer bounce as I was running a light hammer but unregulated. I think and don't quote me on this but I think the hammer slams down fast and bounces off valve seat. Anyway Don warned me about this and he was correct so please DoNot remove pin. I also went back to a smaller bleed port at .030 and it's working very good. Or another possibility is with the large volume of air in the stem with no pin the air doesn't evacuate fast enough causing a strange imbalance inside stem. Not sure but it's not safe

[rsterne]

Travis sent me a replacement poppet for my Cothran valve, as I think I went too far with the 0.035" vent hole.... because I lost some of the peak velocity.... I tried this one with the stock 0.020" vent hole, but with no metering rod, and it acted normally.... The velocity on the plateau (.30 cal. 50 gr.) was the same as stock, ie removing the metering rod didn't change it.... I had no strange effects like hammer bounce, but remember, I am running a #210 90D O-ring on the back of the valve to limit how far the hammer can drive the stem to about 0.075".... and the O-ring then stops the hammer, absorbing any excess energy.... However, with the small 0.020" vent, the valve was back to being "on or off", with a flat plateau and then a sudden cliff, losing the small amount of adjustment you can get with a bigger vent....

I had previously tried a 0.028" vent hole, which worked fine, and then increased it to 0.035", which IMO is too big, because I lost velocity on the plateau.... I think this means that I cannot get enough dwell to max. out the power.... Both the previous sizes were achieved by a pointed burr in a Dremel, which is difficult to get to the correct size, requiring that you keep checking the hole with a piece of wire of the diameter you want.... A couple of days ago, in a local Home Hardware, I saw some Cobalt twist drill that were 1/32" (0.031"), which is in between what I had tried, so that is what I used to enlarge the hole in the new poppet.... Travis had told me that the shaft of the poppet was very hard, and to grind it with a Dremel.... but I picked up a pair of these drills (they were $6.49 for 2) in the hopes that the cobalt steel would be hard enough to do the job.... I used the smallest collet in my Dremel, and ran it at the lowest speed (still probably 5000 PRM), and it drilled the hole out perfectly.... You have to be careful not to break such a small drill, but it was a lot easier to do than using the pointed burr, and the hole will be the same size, every time....

I was very pleased with the results.... I haven't lost any of the peak velocity on the plateau with the 1/32" vent hole.... This compares with a 35 fps loss with the 0.035" hole.... I haven't yet had the opportunity to see how much of an adjustment range I can get with this size.... ie what the knee looks like.... but I'm sure it will be similar to the 0.028" hole, which gave me some degree of adjustability before the steep dropoff.... Plotting that curve, and checking the efficiency on it, will have to wait for another day....

Travis, I'm not getting any flutter or anything else strange happening without the pin, running the #210 - 90D O-ring and a flush hammer face, which gives me about 0.075" of valve lift.... providing I have any gap at all in the SSG....

Bob

[rsterne]

The first trials with the new stem with the 0.031" (1/32") vent hole were a bust.... I removed the metering rod, and over a matter of a few shots at 2900 psi the velocity started to drop.... I had to keep increasing the hammer strike, and even that wouldn't put me back to where I started.... I pulled the valve apart, and found that the seat had a deep groove in it.... I can only assume that by removing the metering rod the valve was closing with such force it destroyed the rather soft seat on the poppet.... Either that, or there was a leak in the force reduction piston O-ring, which put a lot more force on the poppet.... I don't know why I never experienced this with the original poppet, it was still in good shape.... The solution was to disassemble both poppets and build one good one from the two sets of parts....

The poppet is made in three pieces, the hollow stem, the seat, which looks like a nylon washer, and the tubular front part, which is the sleeve of the force reduction system....The two metal parts are threaded together using 10-32 threads and glued, which make the poppet difficult to take apart without scarring the surfaces.... By using the two chucks on my lathe, and turning the headstock backwards by hand, I was able to take the poppets apart.... I used the new stem, with the 1/32" vent hole, and the old seal, turned over to use the flip side, which was perfect, and one of the front sections.... I reassembled it with a drop of blue Loctite and let it cure overnight before assembling and pressurizing it.... It sealed up perfectly first try.... I had installed the stock metering rod, and set about testing it....

As I found previously at 1900 psi, the velocity was right back up to where it was with a stock vent hole.... In .25 cal, there was very little adjustability, basically a plateau and a cliff.... In .30 cal, there was a slight rounding of the edge of the cliff, but the valve was still rock stable just above the dropoff.... With 70 gr. bullets, I did lose a few fps, so there is some indication that this is the largest vent hole you can use in .30 cal at this pressure without losing performance.... I would not go larger, because with the 0.035" vent I lost about 20 fps.... I did some short strings (1 magazine) tethered to my 500 cc tank with the output regulated at 1900 psi, and the efficiency was slightly better than with either the stock vent hole, or with the 0.035" vent, so I think I hit the sweet spot for the vent size, at least when regulated at 1900 psi.... Here are the results....

.25 cal. 34.2 gr. JSB.... 987 fps (74.0 FPE) @ 1.00 FPE/CI, with an ES of 13 fps....
.25 cal 46.4 gr. Cast RN.... 878 fps (79.5 FPE) @ 1.04 FPE/CI, with an ES of 7 fps....
.30 cal 44.8 gr. JSB.... 971 fps (93.7 FPE) @ 1.11 FPE/CI, with an ES of 12 fps....
.30 cal 49.3 gr. Daystate.... 949 fps (98.6 FPE) @ 1.17 FPE/CI, with an ES of 12 fps....
.30 cal 70.0 gr. BBT.... 824 fps (105.7 FPE) @ 1.35 FPE/CI, with an ES of 11 fps....

The .25 gr. pellets required 6 turns of gap on the SSG, the .30 gr. bullets required 5 turns, and the other three all were shot at 5.5 turns of gap.... I can probably get a bit smaller ES by using a lighter hammer, a weaker hammer spring, or a bit less preload on the SSG, to reduce the gap.... I was running the 51 g. MDS hammer with the steel core....

I then took the gun all apart, stripped down the valve, and replaced the metering rod with one I had sanded down 0.003" smaller.... I had heard this was something worth trying, and it produced some interesting results.... First of all, it created a curve where the plateau used to be.... With no gap in the SSG, the velocity dropped about 15 fps with the .25 cal 34 gr. JSBs, and about 40 fps with the .30 cal 50 gr. JSBs.... It then increased until there was 3 turns of gap, and then curved downwards to about 6-6.5 turns and was in the basement when 7 turns out.... I think the lower velocity at heavy hammer strike may be because of the hammer bouncing off the rubber O-ring, although why it should show up only with the undersized metering rod, I have no idea.... The total adjustment range between peak velocity (at 3 turns) and when it rolled over to head into the basement was about 100 fps, so I was quite excited that I would finally be able to get some adjustment in velocity with the Cothran valve without having to play with the pressure.... Unfortunately, for nearly all of that 100 fps range, the velocity was unstable, with the ES increasing as you approached the cliff.... In other words, with the undersized metering rod, I got a slight knee, but not a usable one, as the ES quickly became unusable.... Just before the velocity took a dive, the ES could be as much as 130 fps from one shot to the next.... I fiddled with it, trying various adjustments, but could never get the ES as low as with the stock metering rod, so I took the gun apart and put the stock rod back inside the valve stem....

I tried a few more tests with the stock metering rod and the 1/32" vent hole, and I am very pleased with this combination at 1900 psi.... As long as you stay just above the cliff, in the area where the velocity is 10-20 fps below the maximum at that pressure, you are rewarded with a narrow ES, lots of power without maximum report, and decent efficiency.... I don't think there is anything I can do to get a better tuning range than I have for the Cothran valve, in .25 or .30 cal, when regulated at 1900 psi....

Bob

[oldpro]

 Sounds about right to me. Have you tried running at a lower FPE to see if the Efficiency goes up? Or do you see a pretty similar efficiency across the spectrum?

[rsterne]

The only way to really do that is to reduce the pressure, so no, I haven't done that.... If I reduce the velocity the ES goes up....

Bob

[rsterne]

I took a few shots today tethered at 2900 psi, with the following results....



As you can see, the pellets that were in the mid 900s at 1900 psi are Supersonic at 2900.... I tried some heavier bullets, sized down to fit, and the biggest surprise was the 66 gr. in 25 cal breaking 120 FPE.... I have a feeling that the enlarged vent hole in the stem is hurting the performance of the 109 gr. in .300 cal, as I would have expected more FPE from it instead of less.... After all, the porting is the same as my DAQ, which shot over 180 FPE with the same bullet at the same pressures.... If you correct for my shorter barrel lengths, my .25 cal is about on a par with Lloyd's original experiments with the MRod with the Cothran valve, as is the 80 gr. bullet in the .30 cal, but the 109 gr. is lagging.... It could also be the O-ring bumper on the back of the valve that I have used to limit the hammer travel, I have, after all, done several things to throttle back the valve to work better regulated at 1900 psi.... I guess it's not to surprising that some or all of those changes have combined to knock the top end off the power at the top end.... in fact it would have been surprising NOT to see that.... 

Bob

[3BI5]

Are you guys using any lubing on the cothran valve internals, on the o-ring inside the poppet/valve stem end especially? My valve was acting little sticky and I took it apart to clean it. Now I'm wondering to lube or not. I don't know if the o-ring was installed dry in the first place, but it sure looked like it was dry. And can anyone tell the o-ring sizes and type for the Mrod valve, I'd like to get some spares.

[rsterne]

The force reduction O-ring would be a #006 (1/4" OD x 0.070").... I don't know the material, but mine was translucent/white, so likely Urethane, but I don't know the Durometer (90 is the most common).... I always use a small amount of Dow 55 on all O-rings on installation.... and this should be even more important in a sliding application, IMO....

Bob

[3BI5]

Yes it looked like urethane o-ring. I quess Ultimox will work on it.

I think the sticky feeling on the valve stem was due to valve stem biting in to the brass center. It's like something is trying to push the valve stem sideways alittle bit. Are you seeing any of this on your valve?


By the way Bob, could....... you........ fix....... your....... keyboard..... as..... as..... informative....... your.......... posts............ are............., they.............. are.......... f*****g............ annoying............. to................... read................ for.................................. some......................................reason.....

[rsterne]

Jari..................................................... I don't see anything wrong with my keyboard............................................................................ sorry.... 

The front piston should be free to move sideways slightly on the valve.... that makes it self aligning....

Bob

[Buldawg76]

Just have to read between the ........................ easy peasy......

Mike

[aceflier]

Ok ok it makes power lets see how they shoot.