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Pressure cooker conversion

poacherjoe

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I have an old National # 7 pressure canner with the old petcock system and want to convert it to a weighted system. Has anyone done this? I see a part # 85485 regulator kit but it doesn't say if it's adjustable . Not enough info... I have seen the 3 piece weight set from 5-10-15 lbs and that's what I want but maybe they don't make it anymore and this other kit replaces it.
 

thirdeye

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Can you post the link to the manufacturers site you are looking at? I'm not sure what you mean by 'old petcock' . You may have a straight 15# weight, and going to the 5#, 10#, 15# style should be no problem. A gauge may also be an option.
 

poacherjoe

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The old petcock has a thumbscrew in the top of it and 4 holes on the outside for steam to escape when it is open. It sets on the top of a stem that is mounted in the lid. You leave the screw open for steam to release for 10 minute then turn the thumbscrew in to stop the release of steam so the pressure will go up. Then you have to adjust the temp to keep the pressure close to the pounds you need. This way you have fluctuation of pressure so you have to constantly keep an eye on the gauge. By going to the weighted system once you get the steam at 10 minutes you set the weight on top and adjust the heat till it rocks back and forth to keep the pressure steady and no babysitting is needed. This cooker is very old and it works as is I just want to add the weighted system for simplicity . Several sites offer a presto brand kit but it doesn't give enough info and it isn't the 3 weight system.Have not been able to talk to any customer service yet. Hoping to get the experts here on the forum to explain . When you google the Presto 85485 kit you will see that the picture doesn't show a 3 piece system but maybe it can be adjusted? Presto bought the rights to National years ago.
 

daveomak

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I have an old National # 7 pressure canner with the old petcock system and want to convert it to a weighted system. Has anyone done this? I see a part # 85485 regulator kit but it doesn't say if it's adjustable . Not enough info... I have seen the 3 piece weight set from 5-10-15 lbs and that's what I want but maybe they don't make it anymore and this other kit replaces it.
Yep, I've done the conversion to 2 pressure cookers.... One is an OLD American w/gauge, and the other is a Presto with a 1 pressure rattle weight that was worn out....
On the Presto, seen here, I ran a 1/8 NPT tap down the hole after I removed the "other" support... When I threaded in the All American Canning "post", it leaked a bit so I took some of the liquid JB weld... put it on the re-tapped hole and threads of the post.... Waited for it to set up for a day or so.... Then tried it out.... The weight continually leaked steam... RATS.. thought I ruined my favorite pressure cooker that I do gizzards in..... BUT WAIT !!!!! I noticed it was off of plumb just a bit... the post didn't seal tight to the weight... So I tweaked the post with a crescent wrench 'clamping' it... Made an adjustment or 2 and by golly it works perfect... Now I can cook meats etc. at 5 or 10 or 15 PSI.... AWESOME I tell you.....
Amazon has them... they are worth the price... A 45 year old Presto moves into the 'Space Force' age....

pressure cooker 001.JPG
 

thirdeye

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I guess the petcock style jiggler might diffuse the steam more gently, but if you remove it don't you get the same venting (or maybe better venting?) from the stem itself for the 10/12 minutes. Once you close the petcock I would bet it works as a 15# fixed weight, or am I wrong about this?? Does it not agree with the gauge when the gauge approaches 15#?

When was the last time your gauge was calibrated? If it's reading low, you could be under processing. The local county extension probably has monthly calibration days set-up, call them and see what their schedule is.

oUt9pol.jpg
My oldest canner ↑↑↑ is from the mid 80's and has a gauge, a fixed 15# weight and a 5-10-15# weight (the one shown). I actually need 13#, so I modified the variable weight to jiggle/rock at 13.5# (verified by a calibrated gauge) and I'm good to go.

From what I understand, you have no issues maintaining the proper pressure by using the gauge, you just want a weight to act as a back-up (which is what my canner has)? Here is what my canner looks like in action with the modified weight:

 

poacherjoe

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I live at low elevation and I never go higher than 10 lbs but if I understand you correctly I can do a dry run and see if mine jiggles at 15 lbs . This cooker is from the 1940 era and it works great but I still have to rubber neck it to make sure it doesn't go to high. I will feel much safer installing an adjustable weight and then no more looking over my shoulder. Most folks around here that own these older cookers have converted them to a weight. Presto sells a 3 piece weight but I can't find the stem it rests on. Tomorrow I hope to speak with a representative from Presto to get everything figured out. Maybe the weight will work with my stem? I checked the gauge and it's accurate.
 

thirdeye

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And just curious, how did you check the gauge?

A dry run must have the 3 quarts of water (or what is recommended for your canner's size) and also do a 10 minute venting. Simulate an actual processing. Then, (if the gauge is trusted) the petcock jiggler should rock at no higher than 16#. Whatever you do, don't let it continue to build pressure.
 

poacherjoe

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Ag extension service tested the unit. I just found the info on the net, I need a new vent post and the 3 piece weight set. Thanks for your input.
 

poacherjoe

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Well the Factory Customer care at Presto won't advise you on any of the older pre war canners ! Liability and they want to sell you something new that's made in China ! So as forktender posted pretty much all of these canners are tapped at the same thread size so All American and Mirro brand parts will interchange with the vent post and weight. Presto makes a conversion but the site I found that on was out of stock so I went to Ebay and got everything I needed. Now I have 3 -16 qt. canners that were made in the USA to get more done quicker..
 

forktender

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Even if the threads aren't the same you could always JB weld then retap them to the proper size if all else fails. I absolutely love my 930 All American pressure canner and highly recommend them if you are into canning they are built to last and a true heirloom quality product that is 100% made in the USA.
You won't find another canner that even comes close to the All American autoclave/ pressure canners quality. (buy once cry once.)
 
Last edited:

forktender

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Haha daveomak daveomak
Dave I hadn't read through the whole thread or I would've seen that you fixed up your old pressure cooker using JB weld the stuff kept thousands of muscles on the road back in the day.:emoji_thumbsup:
 

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