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Discussion of diving methods and equipment available prior to the development of BCDs beyond the horse collar. This forum is dedicated to the pre-1970 diving.
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SurfLung
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Joined: Sat Jan 01, 2011 2:03 pm
First Name: Eben
Location: Alexandria, MN
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My Royal Mistral

Wed Mar 29, 2023 2:52 pm

My Royal Mistral
- I've been keeping an eye out for a good deal on a Royal Mistral with a high pressure port. I found one being sold for $250. I offered $200 and the seller accepted. It looked pretty rough but I thought it was coming from Monaco, which is where Jacques Cousteau headed the museum and headquartered his Calypso and diving exploits. So YES... I hoped it was one of JYK's personal regs... At least I could pretend...
- So, then I get this package from Morocco (not Monaco) with cyrillic writing all over it. I opened it up and it was my Royal Mistral...
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- Actually it looked worse than it was... The label was eaten up pretty bad with corrosion. Then to add icing to the cake, the seller had wrapped tape around the regulator and when I took off the tape, it lifted a bunch more of the paint off the label. BUT... It was a Royal Mistral with an HP port and I got a darned good deal on it!
- I showed it to my buddy Ron SheriffDiver and he said he had one of the last replacement labels from Allen. So, I opened it up and found the mechanism intact but poorly adjusted... Actually it was loose. Some diluted vinegar and scrubbing with an old toothbrush got the corrosion and verdigris cleaned up pretty good. The corrosion had lifted some of the chrome plating so it didn't clean up perfect. But it still looks decent. It had a deep scratch in the volcano orifice which I was able to polish out.
- Interestingly, the high pressure seat was dark colored... Which I took to be degradation of the surface and proceeded to attempt a re-facing with flat sand paper in progressively finer grades. This got me down to where I sanded through the dark color directly into brass... There actually was no seat. The volcano orifice was resting directly on bare brass metal! So, I had to replace that seat with one of my parts bin leftovers.
- So now, with a working high pressure seat, polished volcano orifice, and correctly attached and adjusted lever... This thing works perfectly! And with my new lable from SheriffDiver Ron, it looks pretty darn beautiful!
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- I finished it up with a used USD hose loop and curved mouthpiece... Just because it was already put together. I haven't had a chance to dive it yet, but it will definitely get some use this Spring. Meantime, I'm on the lookout for a pressure gauge that will fit the Royal Mistral HP port.
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SurfLung
The Freedom and Simplicity of Vintage Equipment and
Vintage Diving Technique are Why I Got Back Into Diving.

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simonbeans
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First Name: Allan
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Re: My Royal Mistral

Thu Mar 30, 2023 10:12 am

Image

They are back in stock.
www.vintagescubastuff.com
Check out my website: www.vintagescubastuff.com

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Drado
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First Name: Eduardo
Location: Manila, Philippines

Re: My Royal Mistral

Fri Mar 31, 2023 8:53 am

Eben, that looks great!
_______________________________
Ed

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SurfLung
Master Diver
Posts: 1763
Joined: Sat Jan 01, 2011 2:03 pm
First Name: Eben
Location: Alexandria, MN
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Re: My Royal Mistral

Thu Apr 06, 2023 10:33 am

Thanks Allan and Drado!
SurfLung
The Freedom and Simplicity of Vintage Equipment and
Vintage Diving Technique are Why I Got Back Into Diving.

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frogman63
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First Name: Brian
Location: Chelsea, Michigan

Re: My Royal Mistral

Tue Apr 11, 2023 9:30 pm

Eben,
Very impressive. Of course, you must know that to properly dive this reg, you must always speak in French.
The spirit of Falco will be watching over you.

Thanks for sharing,
Brian

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CaptnTomo
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First Name: Tom

Re: My Royal Mistral

Fri Apr 14, 2023 11:42 pm

Hi Eben,
Great job on the renew. I'll wager that she breathes as well as she looks. In gratitude for your effort.

I'm due to take delivery of a Royal Mistral in a week or so. It looks to be in pretty good condition.
I expect that I will go through a similar rebuild process.
I'm wondering if you replaced any of the rubber internal parts, o-rings, gatkets etc. ? Perhaps the duck bill ( bec du canard -fr. ) ?
Thinking a USD exhaust duckbill might work.
I won't know my needs until I open the case but I would appreciate any advice and leads for sources of parts you might have.

Thanks,
Tom

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SurfLung
Master Diver
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Joined: Sat Jan 01, 2011 2:03 pm
First Name: Eben
Location: Alexandria, MN
Contact: Website

Re: My Royal Mistral

Wed Apr 19, 2023 9:49 am

Is this a Frankenstein Reg?
Image
(photo taken at the Lake Wazee divers equipment bench April 14th)

- Evidence is stacking up to suggest that this Royal Mistral may have a USD Mistral nozzle...


1. The nozzle fits on all my U.S. tank valves without modification. I always heard that these have a nozzle that's larger in diameter and must be turned down to fit U.S. tank valves... Chrome is original and there is no evidence of having been turned down to fit..
2. The volcano orifice is not floating... It is machined directly into the nozzle and not removable... Just like a USD Mistral nozzle.
3. The defective HP Seat is identical to the USD Mistral and I replaced it with a good HP seat from a USD Mistral.

Image
(Photo taken at home after changing hoses April 15th)

- It currently breathes so nice that I ditched the used hose loop and installed these brand new flexi hoses and curved USD mouthpiece. However, I just ordered some gray silicon hoses and blue hourglass mouthpiece from Scuba Museum... Should look pretty sharp with the blue color in the label.
SurfLung
The Freedom and Simplicity of Vintage Equipment and
Vintage Diving Technique are Why I Got Back Into Diving.

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SurfLung
Master Diver
Posts: 1763
Joined: Sat Jan 01, 2011 2:03 pm
First Name: Eben
Location: Alexandria, MN
Contact: Website

Re: My Royal Mistral

Wed Apr 19, 2023 9:55 am

CaptnTomo wrote:
Fri Apr 14, 2023 11:42 pm
Hi Eben,
Great job on the renew. I'll wager that she breathes as well as she looks. In gratitude for your effort.

I'm due to take delivery of a Royal Mistral in a week or so. It looks to be in pretty good condition.
I expect that I will go through a similar rebuild process.
I'm wondering if you replaced any of the rubber internal parts, o-rings, gatkets etc. ? Perhaps the duck bill ( bec du canard -fr. ) ?
Thinking a USD exhaust duckbill might work.
I won't know my needs until I open the case but I would appreciate any advice and leads for sources of parts you might have.

Thanks,
Tom
- I thought you might be interested in some other information unique to these HP port Royal Mistrals... When I opened the cans, I could see the little metal HP tube that was welded into the guts of the familiar Mistral mechanism. It looks like it goes to a port just inside of the actuator pin that opens with the levers. From there, it winds around to a fitting that goes through the can. But even this fitting has to be air tight so it's like a tube that is sealed at both ends. And this is what made taking the mechanism out of the can difficult. I had to loosen the inside sealing nut and there isn't alot of room for it to back out and bend around the external port-tube. So, that's what I was meaning about it maybe being a little delicate... I had to press pretty hard to flex that steel tube out from under the port-tube. To finish up, I replaced the HP seat and installed a new silicone diaphragm and duckbill.
- Now Here's Mystery... I couldn't get the HP seat to stop leaking. So I tried re-facing it. Interestingly, the place where the seat sits was dark colored. I thought it was discolored seat material. But what it actually was is tarnished bare brass. The mystery is, how this regulator stayed in service long enough to get as worn and corroded as it was. The metal on metal HP seat... Was it used all that time with a slight leak?
- That seat looked just like a USD Mistral seat and I replaced it with a good USD seat. And now it works just great. But I see that I can order (from Scuba Museum) a Royal Mistral service kit that includes a floating volcano orifice and a slightly different HP seat. My Royal Mistral did not have either.
- This is what has me wondering if it is a Frankenstein Reg.
- Only us vintage scuba guys would be intrigued by this... - Eb
SurfLung
The Freedom and Simplicity of Vintage Equipment and
Vintage Diving Technique are Why I Got Back Into Diving.

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CaptnTomo
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First Name: Tom

Re: My Royal Mistral

Mon Apr 24, 2023 11:37 pm

Hello Eben,
Thanks for the reply
It does seem that we purveyors of these vintage French regs have to combine the Logic of Hercule Poirot with the bumbling yet sucessful results of Inspector Jacques Clouseau. Congatulations on your results.
Perhaps to others, it's a mystery as to why we engage in this activity at all. For me, it's fun, rewarding and as close to time travel as one can get.

In my case, I do not have an HP Port. I believe my model SRM is ( 111 100 ), No 45107. Perhaps I am lucky in this less complicated assembly. I purchased my SRM from The Scuba Museum. It arrived last Friday and is in quite good condition ( I paid almost 2X what you did ). The internals and external rubber parts are very much useable. No corrosion save a small deterioration with the chrome plating on the inside intake housing.
I will have to turn down, by machining, the nozzle if I wish to use with US tank valves. I did find that the existing SRM nozzle will mate with a ScubaPro DIN to Yoke insert on an H valve that I got from the museum. Only, the SRM yoke is too small to actually fit this scheme. I'm looking for a larger yoke as I would like to employ the H valve and accomodate another reg set as a safety measure, at least initially.
It looks like the Scuba Museum is sold out of the SRM kits and duckbills.

I'll have to figure out how to re-size my photos in order to post them here.

Tom

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SurfLung
Master Diver
Posts: 1763
Joined: Sat Jan 01, 2011 2:03 pm
First Name: Eben
Location: Alexandria, MN
Contact: Website

Re: My Royal Mistral

Tue Apr 25, 2023 4:23 pm

Vance made me an adapter for the HP port. It looks pretty much perfect except a little too long on the threaded part that screws into the Royal Mistral (RM). We're shortening it in the shop at my work. Then, I expect it will work fine and I'll be able to connect an SPG to my RM.

Yes Rob had some beautiful Royal Mistrals for sale at the Scuba Museum. I'm glad for you to have snagged one of them!

Regarding my last post about mine being a Frankenreg... Vance made a good point that mine being an HP port model makes it unlikely that the main mechanism is anything other than an original RM.

How I do photos: From my phone, I email them to myself in Medium resolution. That makes them perfect size for this forum. Then, I upload them to photobucket. Then I copy the share link and just insert them into my posts using the img tool. Here's a photo of the RM HP adapter that Vance made for me. You can see the original port plug laying on the bench. This photo was taken before we shortened the threaded section... It's sticking out because this is as far as it will screw in. I'll post a photo of it fitting all the way in later.

Image
SurfLung
The Freedom and Simplicity of Vintage Equipment and
Vintage Diving Technique are Why I Got Back Into Diving.

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CaptnTomo
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First Name: Tom

Re: My Royal Mistral

Fri Apr 28, 2023 5:49 pm

Looking good. It's nice to have the port for the SPG available.
I wonder about the Frakenreg theory. I have not seen any drawings of the Spiro RMs that show a fixed volcano orfice in the valve body. Then also, I wonder how say a body from a USD DW Mistral would have an HP port available for the external connection to the spg. A Mystery ? Having an uncut nozzle that fits US tank valves makes me wonder if maybe Spiro got some USD Mistral valve bodys and modified them to fit their RMs for sale in the US. However, One would think that the HP port threads would have been made US compatable.
The drawing I have for the DW doesn't seem to show a removable volcano.

My SRM Model 111 100 has a removable volcano orfice called a " Siege " ( seat in English ) part # 111 305. The mating piece # 111 307 is called the Clapet garni , fill valve in English. It seems reversed from the way we name them. Both appear to be in great shape in my reg.
The duckbill is also very good. For future service, I wonder if USD/Voit duckbills would work in the SRM ? It looks like they should fit.

Here is a photo of my reg just after opening the shipping box. I resized the file and this one worked.
IMG_20230421_142727183_HDR.jpg
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Vancetp
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Joined: Tue Oct 04, 2016 7:26 pm
First Name: Phillip
Location: Belmont CA

Re: My Royal Mistral

Sat May 06, 2023 8:02 pm

Eb made the correction to the length of the threaded end of adapter, and it now works! Awesome!

I made Eb's adapter from measurements of a Spiro adapter provided by an owner of one of them. It seems that Spiro made various adapter ports, male and female, shorter and longer, etc.

I made this adapter w/o having a regulator to test fit with. I'm glad it worked out.

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