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Post by Jim Perdway on Mar 8, 2022 12:36:26 GMT -8
I'm working on my Mistral rebuild and I wish I would have read this thread beforehand, as I'm realizing I did something incorrectly. Anyway, I struggled to remove that really small o-ring from the pinhole on top (I'm guessing this is what Phil refers to as the HP valve o-ring), but I had used a steel pick. I can't see very well inside and I'm not really sure what the brass looked like before removing the o-ring. I know it didn't go down and make contact with the HP seat, so I'm wondering what area would be problematic if it were gouged. I've seen the term HP valve seat discussed on here, but I'm not sure which part that is.
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Post by SeaRat on Mar 8, 2022 13:06:20 GMT -8
I'm working on my Mistral rebuild and I wish I would have read this thread beforehand, as I'm realizing I did something incorrectly. Anyway, I struggled to remove that really small o-ring from the pinhole on top (I'm guessing this is what Phil refers to as the HP valve o-ring), but I had used a steel pick. I can't see very well inside and I'm not really sure what the brass looked like before removing the o-ring. I know it didn't go down and make contact with the HP seat, so I'm wondering what area would be problematic if it were gouged. I've seen the term HP valve seat discussed on here, but I'm not sure which part that is. The answer is not to worry much about that O-ring, or any gauge. The O-ring only helps direct air out the Mistral orifice, and any gauge will simply allow some more air into the case. It’s not a big deal, and I have never removed the O-ring from any of my Mistral regulators (actually, I have only one now). So don’t sweat it, and go on to more important stuff. John
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Post by Jim Perdway on Mar 8, 2022 13:22:24 GMT -8
That's encouraging- thanks John! I wish I had just left that o-ring in because now I'm facing the task of putting in the new one. I figured since it came in the rebuild kit it was standard to replace it.
Edit: With some spit and the plastic end of a mechanical pencil, I was able to get the o-ring in easily and it only took about a minute, maybe less. Felt like a miracle happened
Just out of curiosity, how could any gouges have an effect on air flow if it is primarily sealed by that o-ring?
Also, for adjusting lever height, why does it matter what psi the tank is at? In the manual it says to do above 2K, but Mark you said it should be done around 500?
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Post by h2operations on Mar 8, 2022 14:20:36 GMT -8
Ouch. As a purist, I cringe when I hear this. If you're going to throw the clips away, please save them for me. As far as I know, there is no source for newly produced clips, and people like me will desperately need them some day down the road and will be thankful to have them. While I appreciate the purist c-clip approach, I take my DH reg cans apart after each dive trip (whether one day or a week long) so from a practical-ist perspective, c-clips are a PITA. Do love the look though. A little off-topic, but the only "pure" restoration I have ever done (down to the c-clips), is a 2-stage Voit VR-2 Mariner. Works as great as a non-venturi assist reg can, but I have only used it in fresh water a few times. For anyone intetested in that rebuild, I started a fairly extensive thread a while back over on VDH. www.vintagedoublehose.com/forum/viewtopic.php?f=4&t=9541I have several NOS c-clips in my parts boxes. I plan on doing an original restore to an AquaMaster. NICE STASH BOX!
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Post by vance on Mar 8, 2022 16:05:27 GMT -8
That's encouraging- thanks John! I wish I had just left that o-ring in because now I'm facing the task of putting in the new one. I figured since it came in the rebuild kit it was standard to replace it. Edit: With some spit and the plastic end of a mechanical pencil, I was able to get the o-ring in easily and it only took about a minute, maybe less. Felt like a miracle happened Just out of curiosity, how could any gouges have an effect on air flow if it is primarily sealed by that o-ring? Also, for adjusting lever height, why does it matter what psi the tank is at? In the manual it says to do above 2K, but Mark you said it should be done around 500? So, even if you managed to maul the valve body o'ring opening, it won't matter too much. All that o'ring does is seal the HP pin in an effort to minimize the amount of air escaping around the pin and going straight up into the box. That isn't critical. The Scuba GL, which is much like the Mistral, doesn't use an o'ring at all. And we all know how good a GL breathes, eh? It would probably work fine w/o an o'ring installed*. In fact, a bit of air discharge straight up into the diaphragm is a good thing, helping the lever spring to return the diaphragm to it's extended position. *Well, maybe not fine. I haven't tried it....
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Post by SeaRat on Mar 8, 2022 17:06:56 GMT -8
That's encouraging- thanks John! I wish I had just left that o-ring in because now I'm facing the task of putting in the new one. I figured since it came in the rebuild kit it was standard to replace it. Edit: With some spit and the plastic end of a mechanical pencil, I was able to get the o-ring in easily and it only took about a minute, maybe less. Felt like a miracle happened Just out of curiosity, how could any gouges have an effect on air flow if it is primarily sealed by that o-ring? Also, for adjusting lever height, why does it matter what psi the tank is at? In the manual it says to do above 2K, but Mark you said it should be done around 500?Well, it won't matter much. But the higher pressure will put more pressure on the pin, which may increase its height a bit, and affect the ultimate height of the levers. I've pretty much ignored this, and adjust the height until it is high enough to engage the diaphragm and not hiss when I press down on the top box before it is assembled. That way it is at max height, and will perform best. John
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Post by Jim Perdway on Mar 8, 2022 18:21:32 GMT -8
My rebuild is done and I'm excited to test it out. Still going to be a few months 'til I can though JTFM rebuilt by Jim Perdway, on Flickr
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Post by h2operations on Mar 8, 2022 18:32:10 GMT -8
I love the Jack the Frog Man Stickers.
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Post by Jim Perdway on Mar 26, 2022 16:31:20 GMT -8
Has anyone encountered an orifice that’s very difficult to remove? If so, any tips for doing it without breaking the thing?
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Post by vance on Mar 26, 2022 16:59:28 GMT -8
You really don't need to remove it. If you have to, apply heat. Use a regular old propane torch. I have some regs with screws and nuts and what-all that were very stuck with corrosion. I sprayed them, bagged them, sprayed them again, and let them sit for months. No luck.
I'd skip the spray and go directly to heat next time. No smoky stink when you heat the parts!! Use a box end wrench so you don't round the corners with an open end.
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Post by Jim Perdway on Mar 26, 2022 18:06:58 GMT -8
Thanks, I suppose if I don’t have to then I’ll leave it. Is there a good reason that part was made to be removable?
Also, the Mistral I’m working on now is serial number 111024 with West Pico address, if anyone can help me narrow down the production year. I was told mid to late 1960 but I didn’t think they were at that address in 1960
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Post by vance on Mar 27, 2022 9:36:26 GMT -8
Is there a good reason that part was made to be removable? It was probably made that way for cost saving reasons. They already had the tooling set up for the OverPressure regulators which use basically the same valve body, but have a hose connector screwed into it. They simply made a venturi nozzle that fit the same hole. This also allowed USD to easily retrofit Mistral nozzles into StreamAirs and the hose in a hose OverPressures. They slapped a curved yellow Mistral label on them to show they had been converted. There were conversions done by owners, so it isn't unusual to see a StreamAir or OverPressure with the Mistral nozzle, but no Mistral label.
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Post by artc on Mar 27, 2022 10:43:02 GMT -8
Hi Stephan, that’s one sweet Mistral you have there. Let us know how it breathes when you take out diving. 👍
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Post by Jim Perdway on Mar 27, 2022 11:36:11 GMT -8
Interesting, thanks! I didn’t know that you were so familiar with USD stuff
Yes in a few months I’ll report back with my experience, although I’m not a good judge of performance; I dove my RAM and Clipper back to back and couldn’t tell any difference. The R-3 though…I like that “Easy” is a even labeled as a setting haha
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Post by SeaRat on Mar 27, 2022 14:43:12 GMT -8
Here is one of my Mistral dives, under somewhat trying conditions, river diving. It breathes really great, especially at around 500 psig.
John
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