250Z Barra 250Z 22 plenum install

[Pumacarl]

If I were going to do this, what would you use? A set screw? What size and how long? Would you use some kind of thread tape or sealant? Forgive my ignorance, I’m new here and learning as I go.

Yes, ideally a set screw. Match what is under the gauge, sometimes they have a derlin washer. If you can't do that, yeah Teflon thread tape. There's no instruction manual on diy projects, you just keep trying until you find what works.

I would just look up what size the threads are on those gauges and do a quick look at a hardware store for one, but in all likelihood you'd have to order one from Mcmaster-Carr. I hate to pay the shipping but they have just about everything and are the only place that will sell small quantities to individuals. There's a lot of leg work to tinkering. Try Amazon first though, free shipping, if not, mcmaster.com.

The other thing you could do, that is the simplist, is just buy a couple of extra gauges and if you do break one, replace it.

 

[cosmic]

8x1 should be it

 

[BSJ]

The plug has to be rated for at least 4500psi.

Some random set screw might not be.

 

[Pumacarl]

The plug has to be rated for at least 4500psi.

Some random set screw might not be.

If the set screw is made of steel and threaded properly, what ever component you are screwing that into will fail first. The bigger concern is overtightening and stripping whatever your putting the setscrew in. A real setscrew is not some random screw. They are made to hold machined steel collars on smooth steel parts. I wish they made airguns tough enough that that was the weak link.

 

[Logandiana]

If the set screw is made of steel and threaded properly, what ever component you are screwing that into will fail first. The bigger concern is overtightening and stripping whatever your putting the setscrew in. A real setscrew is not some random screw. They are made to hold machined steel collars on smooth steel parts. I wish they made airguns tough enough that that was the weak link.

Maybe the better thing to do would just be to ask y’all. I used some AI to point me in the right direction, but what it pointed me to was different that I thought y’all might be talking about here. So…Who has successfully done this and what specifically did you use for a plug? Can you give me a link?

 

[Pumacarl]

Maybe the better thing to do would just be to ask y’all. I used some AI to point me in the right direction, but what it pointed me to was different that I thought y’all might be talking about here. So…Who has successfully done this and what specifically did you use for a plug? Can you give me a link?

Probably nobody has done it. I just told you what I would do if I was going to do it. So what do you do now if nobody has already done it? Nothing? Why? It's a part designed to take a part, an M8x1 part, look for a plug and plug it. Life can be that simple. Make sure it's a steel part of good quality and go to town. I would use this part: McMaster-Carr, that took me all of 2 minutes to search for. I'm not recommending for you to use this particular part, I'm recommending you do your own research and buy what looks good to you. If you have the plenum you want to plug in hand check and see if there is a derlin washer at the bottom. If so, you probably won't need to use any tef-tape, and measure the depth in mm so that you get an appropriate length. You don't want it sticking too far out, if at all, when tight. Since you are supposed to take out your guage from your gun and stick it in the bottom of your new plenum, you know it's that thread and you can measure how far down that one will go to get the depth too. So you can order the length you need. This is how tinkering works. When your done and it's working you can post a link for others to use as you will be the first. Welcome to HAM, and to modding.

 

[Logandiana]

Probably nobody has done it. I just told you what I would do if I was going to do it. So what do you do now if nobody has already done it? Nothing? Why? It's a part designed to take a part, an M8x1 part, look for a plug and plug it. Life can be that simple. Make sure it's a steel part of good quality and go to town. I would use this part: McMaster-Carr, that took me all of 2 minutes to search for. I'm not recommending for you to use this particular part, I'm recommending you do your own research and buy what looks good to you. If you have the plenum you want to plug in hand check and see if there is a derlin washer at the bottom. If so, you probably won't need to use any tef-tape, and measure the depth in mm so that you get an appropriate length. You don't want it sticking too far out, if at all, when tight. Since you are supposed to take out your guage from your gun and stick it in the bottom of your new plenum, you know it's that thread and you can measure how far down that one will go to get the depth too. So you can order the length you need. This is how tinkering works. When your done and it's working you can post a link for others to use as you will be the first. Welcome to HAM, and to modding.

So my initial search resulted in the exact same part. But then I read comments about pressure ratings, where this one is unrated, and that it shouldn’t be a standard set screw but rather a tapered plug. I did find one somewhere else that looks exactly like what I need, it’s sold for high pressure hydraulic systems, but it’s only sold through the manufacturer in quantities of 100. When I originally came across this thread and the users of the c88 plenum I assumed this plug mod was fairly common and had been tested. I may just have to be the guinea pig on this one.

 

[Pumacarl]

So my initial search resulted in the exact same part. But then I read comments about pressure ratings, where this one is unrated, and that it shouldn’t be a standard set screw but rather a tapered plug. I did find one somewhere else that looks exactly like what I need, it’s sold for high pressure hydraulic systems, but it’s only sold through the manufacturer in quantities of 100. When I originally came across this thread and the users of the c88 plenum I assumed this plug mod was fairly common and had been tested. I may just have to be the guinea pig on this one.

Well, that's news to me, an M8x1 is not a tapered part. Some of these guages are not standard and are tapered but I don't think these guages are. Somebody reading this will hopefully chime in. This is how it goes with modding, a lot of research and reading up on stuff. Not everything is going to have a pressure rating either, especially if it doesn't hold pressure. Emailing C88 and asking about the threading wouldn't be a bad idea either.

 

[Pumacarl]

So my initial search resulted in the exact same part. But then I read comments about pressure ratings, where this one is unrated, and that it shouldn’t be a standard set screw but rather a tapered plug. I did find one somewhere else that looks exactly like what I need, it’s sold for high pressure hydraulic systems, but it’s only sold through the manufacturer in quantities of 100. When I originally came across this thread and the users of the c88 plenum I assumed this plug mod was fairly common and had been tested. I may just have to be the guinea pig on this one.

You know I just looked at the guage that goes in there, and yeah it's not tapered, and it looks like it's made out of brass. I, myself, would get that setscrew that I listed w/o hesitation because there is no way that the Barra guage is tougher than a steel solid setscrew, I'd bet my life on it, but that's just me.

Like I said, do your own research, don't believe me or anybody else, unquestionably. Some say I'm flippant, I say they are scared of everything, and don't want to do anything. I do my research, and I'm still here. There is so much fear mongering over HPA that it surprises me that it is even a thing sometimes. A lot of people over at another forum got upset and complained constantly about people working/modding on their own guns because (I believe) they wanted a chance to buy an "unmolested" almost new gun. Tinkerers hurt the used gun market. Like I care about the buy and try crowd. Then people will tell you that you need a $5K compressor with big filters or you will be using wet dirty air, again, ridiculous if you know what you're doing. I have a cheap $50 Amazon hand pump that went seven years before I had to replace an oring on it, no filter, and the gun I use it on has never had a drop of water in it. If you pump correctly you will never pump water into your gun, or damage even a cheap pump. This sport should be taken seriously, but it obeys the laws of physics, no magic here or mysteries. It can hurt you if you're careless, but if you're not careless, you don't need to be afraid of it either. Have fun working on and playing with your airgun.

 

[BSJ]

There's "being afraid of everything" and being smart enough to respect what pressurized systems are capable of. Those who don't respect the danger are people that end up with Crosman a valve through a leg.

There are legitimate plugs at McMaster, but only rated for 3000 psi. Which would work, if you can guarantee your reg would never fail.

Pressure gauges are cheap. Replace it if it gets scratched. Probably cheaper than a propper plug...

 

[cosmic]

I would replace it with a stainless steel hex...