# Chambers Stove Adjustable Orifice Caps



## Dwayner1 (Aug 17, 2020)

New member here with a question about orifice caps on 1945-1951 Chambers stoves.

I restore these old beauties as a hobby and have a friend who is pretty sharp when it comes to gas stoves since he was in the industry many years ago.  But, he can’t remember what the issue is with a certain adjustable orifice cap and why I should NOT adjust down from NG to LP without switching out the cap first.

Story.....I’ve taken apart maybe 25 Chambers stoves and while a few did have just the predrilled set orifice caps for LP, most have adjustable caps.  Now the one called the “Universal” cap came out on the model C stoves and is probably like the modern stoves.  If you want to convert to LP you just tighten down the cap to the mixer pin and the predrilled hole inside the mixer pin is set for LP.  My issue with that is that I’ve hooked up 5 stoves to 5 different tanks and I can never get the burner flames low enough.  And, I can’t believe that all 5 tanks had a higher than 11” WC pressure causing the issue.  Suggestions?

But my real question is this...Chambers also made an orifice cap with a pointed mixer pin that did NOT have a hole predrilled for LP.  However,  these types of orifices work perfect on LP because I have 100% control over the gas flow from full open to full off.  My friend says you should not use that style adjustable cap for LP unless you change the cap out to LP on each burner.  He can’t remember why but he said it was covered in one of his training classes years ago.

Can anyone shed any light on why that style adjustable orifice cap / pin can’t be used on LP without changing out the cap?

I’ll try to post pictures later today.

Thanks!


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## Dwayner1 (Aug 17, 2020)




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## Dwayner1 (Aug 17, 2020)

I borrowed the picture above from another forum but it’s a good one of the mixer pin I’m talking about.  There’s no hole at the point like the Universal types.  Is it still OK for LP?


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## coaly (Aug 19, 2020)

When you can’t turn it down far enough for the point to protrude enough through the orifice, a bottoming tap is used in the cap so the threads go deeper in it. Too far can close them entirely, which isn’t a problem since they turn hard enough to not not move on their own.

  You can experiment with the orifice size with a drop of solder over the hole, drill by hand smaller than original. You can always remove solder and try again if you fail. Just don’t drill any brass out of the cap. Use a pin vise and orifice drill the right size for btu desired. (From a chart using 10” WC.) Even if pressure is a bit over 11, with flow it is slightly lower at the orifice. Check pressure with a few burners on, or another appliance burning on the same system.  You don’t want to size orifice using lock up pressure with no flow. That can be higher. (When you stop flow, it takes time for pressure to build and regulator to respond. This is lock up pressure)


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## Dwayner1 (Aug 20, 2020)

Thanks for the input.  I’ve done the drilling in some caps before and have a set of small bits to play with.

But to ask again, that style of mixer pin that is pointed and does *not* have the center hole like a Universal pin, can I just tighten down the cap onto the point of the pin until the LP flow is right, without changing the cap on there now?  Or maybe your stating that I *should* solder the cap and drill to a smaller hole for LP even with the pointed pin inside?


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## coaly (Aug 20, 2020)

You should be able to. You can tell the difference between a resistive turn like an anti vibration locking thread and tight. It will stop when turned down as far as it should go. Don’t remember any reason why that orifice can’t be tight for that burner. Do you get any yellow flame tips when turned down tight?


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## coaly (Aug 20, 2020)

Is the pin protruding through the orifice cap a little? If not, maybe it is turning hard and you may think it is tight. They are snug when turned down, like hold your breath is this going to break snug. That’s why I like to clean threads with wire brush and run a bottoming tap in orifice cap. Never broke one, but I’m sure it’s possible.


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## Dwayner1 (Aug 20, 2020)

If your asking about the Universal pin with the hole in the center of the point....no, it’s flush with the cap when tightened down all the way.  Still, the flames when using LP are a little too high for my taste.

If your referring to the pointed pins with no hole in the center of the point....yes, the point does stick out just a hair when the cap is tightened down to get a good LP flame.

Im good on the cap issues and how to drill or change out the caps to LP based on hole size and BTU output needed per burner size.  But, I’m still wondering why the pointed pin with NO hole at the center cannot be adjusted down for LP without changing the cap to LP.  My friend says it’s not recommended but can’t remember why.


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## Dwayner1 (Aug 20, 2020)

coaly said:


> You should be able to. You can tell the difference between a resistive turn like an anti vibration locking thread and tight. It will stop when turned down as far as it should go. Don’t remember any reason why that orifice can’t be tight for that burner. Do you get any yellow flame tips when turned down tight?



Maybe a little yellow at the tips but not usually....I think that normal for LP?

Anyway, I really appreciate your help.  I’ll keep doing as I have and keep in touch with my clients to make sure all stays good with those style pins using LP.

Thanks!


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## coaly (Aug 20, 2020)

Yes, I was referring to the solid pin coming through the orifice. It should.

All blue flame only. Yellow is rich unburned fuel, and a carbonizing flame that deposits carbon on the pan bottoms. Setting a pan over the flame can add some yellow, but with nothing on it, only blue. That is how to tell if the orifice is too large for the burner. It will have too much fuel for the air intake size and have yellow tips. Close the hole down until the yellow is gone. As it is made smaller for less btu, the air shutter needs to be closed to match the correct air fuel ratio.

I think the natural orifice is squared off inside where drilled and the LP may be angled like a countersink was used inside to match the angle of pin tip. The natural cap may contact pin if tightened down too tight damaging tip. That may be what he remembers. It’s been a long time for me too. 13 years since retiring from my own Propa


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## Dwayner1 (Aug 21, 2020)

coaly said:


> Yes, I was referring to the solid pin coming through the orifice. It should.
> 
> All blue flame only. Yellow is rich unburned fuel, and a carbonizing flame that deposits carbon on the pan bottoms. Setting a pan over the flame can add some yellow, but with nothing on it, only blue. That is how to tell if the orifice is too large for the burner. It will have too much fuel for the air intake size and have yellow tips. Close the hole down until the yellow is gone. As it is made smaller for less btu, the air shutter needs to be closed to match the correct air fuel ratio.
> 
> I think the natural orifice is squared off inside where drilled and the LP may be angled like a countersink was used inside to match the angle of pin tip. The natural cap may contact pin if tightened down too tight damaging tip. That may be what he remembers. It’s been a long time for me too. 13 years since retiring from my own Propa



Great info.  It’s like restoring these Chambers stoves made 70 years ago, no one knows all the hows and whys on what they did but we learn a little at a time and pass on the information.  Thanks!


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## coaly (Aug 21, 2020)

There’s a really good manual you can get from Ed at  antique stoves from the appliance club.


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## Dwayner1 (Aug 21, 2020)

Great, I’ll look into that.


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## stumped (Mar 29, 2021)

Coaly-Thank you for all the time and expertise you have volunteered.
I have a 50's Wedgewood with fixed dual orifice valves on burners.  Should total 9000btu with the inner simmer doughnut plus the outer larger doughnut.  I redid burner orifices-using #86 (simmer) at about 1000 btu(it appears OK but a little low) and #65 (main) 8500 btu then combined they are 9500 and should have worked at least on the larger front burner correct? Unfortunately there is still toooo much yellow even with the air shuttle wide open. I wish I could find someone willing to tell me what the orifice sizes should be for LP on this So I don’t have to experiment. The original NG holes were #55 main doughnut and # 75 for the simmer.  Stamped on the plate is 9000-18000-and 24000.  If I have to I will drill until I hit the correct size.


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## coaly (Mar 30, 2021)

Orifice size looks correct. Did you check gas pressure? Are there other appliances on the system? Twirl a pipe cleaner in the burner through the air intake to make sure there are no webs inside the burner or mixing tube.


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## EDN9HT (Dec 8, 2021)

I'm sorry if this is not the exact right place to post this question but it is as close as I can find.  Having trouble figuring this app out .
Was hoping to find someone familiar with Chambers gas range 41c.  It has lp orifice's and I have ng.  Have been searching with no luck for info on orifice drill sizes and/or btu ratings for each burner and I can calculate the size.
Can anyone help?


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## coaly (Dec 9, 2021)

EDN9HT said:


> I'm sorry if this is not the exact right place to post this question but it is as close as I can find.  Having trouble figuring this app out .
> Was hoping to find someone familiar with Chambers gas range 41c.  It has lp orifice's and I have ng.  Have been searching with no luck for info on orifice drill sizes and/or btu ratings for each burner and I can calculate the size.
> Can anyone help?


You don’t need to know what appliance you have. The size of an orifice allows a metered amount of gas vapor through at any given pressure. You simply want to keep the BTU capacity of each burner the same with different specific gravity gasses.

Are the orifices numbered? If so, simply drill out to corresponding BTU size of the natural gas orifice.  Size is different for the pressure being used which is set by appliance regulator. (Natural Gas is normally 7 inches water column or 1/4 psi)

If no number on orifice, you need to test with orifice drills to find the size first, then drill out to corresponding BTU size of natural orifice at the pressure you are using.
Google search; “LP orifice chart”



			https://ssl.ca/wp-content/themes/sinclair-supply/pdf/Gas-Orifice-Capacity-Chart.pdf


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## EDN9HT (Dec 9, 2021)

coaly said:


> You don’t need to know what appliance you have. The size of an orifice allows a metered amount of gas vapor through at any given pressure. You simply want to keep the BTU capacity of each burner the same with different specific gravity gasses.
> 
> Are the orifices numbered? If so, simply drill out to corresponding BTU size of the natural gas orifice.  Size is different for the pressure being used which is set by appliance regulator. (Natural Gas is normally 7 inches water column or 1/4 psi)
> 
> ...


Thank for your response!
The original lp orifices are not numbered, I wish they were it would make things so much easier.  
I have converted my last stove years ago by finding the drill size of the orifice and looking up the btu of each burner and then finding the corresponding drill size for ng.
I was just hoping with this old Chambers stove having so many people into restoring them that I'm sure have already figured out the btu's or ng orifice size. 
Just trying to save a step or two.  And thank you for the link to the conversion chart...  Saved me from having to go out and dig through boxes in the shed for my old books.
Also was hoping not to have to go buy an entire set of drill bits to check size instead of just the bit I need to drill.  
I will if I have too.

Thank you again for your help!


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## coaly (Dec 9, 2021)

EDN9HT said:


> Thank for your response!
> The original lp orifices are not numbered, I wish they were it would make things so much easier.
> I have converted my last stove years ago by finding the drill size of the orifice and looking up the btu of each burner and then finding the corresponding drill size for ng.
> I was just hoping with this old Chambers stove having so many people into restoring them that I'm sure have already figured out the btu's or ng orifice size.
> ...


If you have a micrometer or vernier caliper, insert  a tapered needle into orifice. Mark with tape the depth it goes. Measure diameter as that point. That will get you real close. Notice the size for natural is just under double the LP size.


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