Dacor Olympic 400/800 regulators

[artc]

Hello everyone, new guy here. Recently, I acquired two Dacor regulators, a 400 and an 800 plus some extra matching second stages. I serviced the second stages and was amazed at the ingenuity and simplicity of them. Easiest tuning of any second stage I’ve ever seen. I like the twin exhaust ports too. I didn’t need to replace the lp diaphragm as it was in great condition. 

The first stages are awesome and built like tanks. They breathe great and have no leaks or corrosion. However, I don’t know their history and should service them. Judging from the Dacor service manual, service looks pretty straightforward. I’ve read that parts are hard to find, but assuming the hard parts are okay, all they need are the hp diaphragm, hp seat and some o-rings. The diaphragm seems to be exactly the same size as the USD Conshelf ones. I have all the tools and o-rings that would be needed, so that only leaves the hp seat. 

if necessary, I will polish the original hp seats and put them back in the regulators, but I would prefer to replace them with new seats. My question to the experts is; can I use a Trident A213 seat to replace the original OEM seat? If not, are there other aftermarket seats available for the 400/800 series? I’m out of my lane with Dacor regulators, so please help. Thanks so much. 

[cnotthoff]

I've used those seats from Trident on a few Dacor regs with good results.

Dacor messed around with different length pins over the years, so measure the length of your existing seat and pin combination, then make sure the replacement is the same length.

Good Dives,
Charlie

[SeaRat]

I also have several Dacor Olympic regulators, and think you probably can still use the original seats. You can take a look and see whether they actually need a polishing or not too. Dacor regulators were known for being very robust regulators, and the Olympic series, as one of our members has stated, was really over-designed. It even has a double filtering system on it. I have been using the successor to the Olympic regulators, the Pacer series, for several decades without troubles.

Check the circlip that holds the purge button onto the cover though. I have one second stage where that circlip corroded and fell off. And, I think Dacor issued a recall based upon that too.

John

[artc]

Thanks Charlie. That's a cool avatar you got there.

Thanks John.  My concern is that once I move the original seat out of its position,  I'll have to polish it as I won't be able to place the seat back in it's original relationship to the volcano orifice. On the other hand,  the regulators work perfectly with no creep and good lock up.

You're spot on regarding the second stages. I have six of them that i just serviced and only one circlip didn't break. I have an order with McMaster Carr for replacements. 

[cnotthoff]

I was going through my Dacor stock today as I was reviving a Pacer Aero (not their finest hour). I may have some Dacor purge circlips. I have a bunch box tops. My foggy memory is telling me that Dacor changed the tiny purge button to something bigger, so the top was changed. I'll look into that next time I'm in the shop.

Good Dives,
Charlie

[SeaRat]

Dec 27, 2021 19:00:57 GMT -8 artc said:

Thanks Charlie. That's a cool avatar you got there.

Thanks John.  My concern is that once I move the original seat out of its position,  I'll have to polish it as I won't be able to place the seat back in it's original relationship to the volcano orifice. On the other hand,  the regulators work perfectly with no creep and good lock up.

You're spot on regarding the second stages. I have six of them that i just serviced and only one circlip didn't break. I have an order with McMaster Carr for replacements. 
(emphasis added, jcr)

Art,

I understand your concern, but I think on a balanced diaphragm first stage, as long as the regulator is not pressurized, the pin holds the seat away from the sealing surface. It takes about 140 psi interstage pressure to allow the smaller spring to push the seat closed, if my memory is correct. So if it has had very little use, even if fifty years old, that seat may not have had much contact with the sealing surface.

John

[nikeajax]

Art, don't trip on it too much bruddah! I've never had this happen with any of my old regs: just inspect it and make sure it's clean of any schmootz. 95% of the time, if they're gunna leak at all, it will be the first time you add air...



They're either good'r they ain't, see!

Jaybird

[artc]

Thanks nikeajax. The regulators are is really great condition with no signs of vertigris or corrosion. I’m sure these are fresh water regulators as living in Hawaii, I’m very familiar with gear exposed to saltwater. The second stages were also extremely clean. All I did was take them apart, clean them in soapy water, replace the exhaust valves and o-ring on the orifice. Tuning them and setting the levers was a snap.

The first stages likely need new o-rings and diaphragms, so I’ll be taking them apart for replacements. If I can figure out how to attach photos, I’ll share them with the forum.

[nikeajax]

Hi Art, you may want to make an IP adjuster tool, like mine:



Here's a little Dacor-porn ta get ya hot an' bothered...











I know, I evil that way

JB

[artc]

Oh my!!! 🤩 That gear is awesome, nikeajax. Yes, I have an IP adjustment tool. Years ago, I made one from a Plomb 5444 1/2 inch drag link socket to remove the end caps on USD Calypso’s and as luck would have it, it fits the Dacor 400/800 adjustment screw perfectly.

[herman]

I had a chance to look at some Dacor documentation I have and you might make it work but you WILL have to replace the pin. According to the chart I have, the 960 seat (which is what the A213 claims to replace) has a pin hole depth of 0.237 inch while the 400/800 seat has a pin hole depth of 0.270in or a 0.033in difference. That amount of difference will have a dramatic effect on the regulator so you will have to make changes in the pin length to account for the difference in depth. I don't have any info on the diameter of the hole, I assume it's the same but no way of knowing for sure without both seats in my hands. The pin replacement MUST be hardened SS, otherwise it may corrode and would possibly be to soft as well. These pins are pretty hard material, use too soft of a material and the pin may bend, not a good thing deep underwater.
Looking at the 400/800 manual, the pin is part of an assembly, I don't know how hard it will be to remove/replace the pin, you may have to use a different pin pad and pin to accomplish what you need.

[vance]

I ran into an old post of mine today. In it, I was discussing a 400 I was rebuilding that had a roll pin (vertically split tube) as the HP seat pin.

I remember that regulator. I remember that the roll pin had been shortened, and the end was mangled by whatever nippers were used to cut it. Consequently, the end didn't fit in the pin carrier well.

I thought that someone had subbed in a bit of roll pin, so I checked by disassembling another. It also had a roll pin, so I cleaned up the mangled one, matched the length to the other pin, and reassembled the reg. It worked perfectly.

I've never seen a roll pin in any other regulator.

[vance]

Artc,

You might already be aware of this, but Herman and I both made double hose regulators out of the Dacor Olympic 4/800.

Herman's was first, and I went to school on him to make mine. The designs are very different, but both are housed in FX boxes.

If you are interested, Herman wrote his up on VintageDoublehose.com (search for Dacor Derringer), and there is a lengthy thread here on Proboards on mine (search for Dacor DH conversion).

The 4/800 is a really fine regulator!

[artc]

Thanks Herman. I suspected that the using the A213 hp seat would necessitate some modifications to the pin and pin support. I’m going to order the seat and experiment with it. Since the 400/800 pin and support are permanently attached to each other, I’m not going to mess with it. Instead, I’ll try some pins and supports from early USD regulators. I already have extras from some Conshelfs and will go from there.  If I’m not successful, I can always polish the original seat and there might not even be a need for that. I’ll post my progress and share with everyone.

[artc]

Thanks Vance. Yes, I read your Dacor DH thread with great interest and admiration. My ambition with my 400/800’s is much more modest. My goal is to make these regulators look and work like new. They already work as they should, but I don’t know their history and suspect they haven’t been serviced in decades. I will take your advice and read Herman’s thread. Thanks again.