dodge28 Posted March 5 Share Posted March 5 😁I am seeing on this forum quite a few members are having broken distributors , caburetos and other components made from Pot Metal are breaking up. The mixture of pot metal are not really good on some components. After some years of service they crack . Ask the Jon the Carb King. 1 Link to comment Share on other sites More sharing options...
DFeeney Posted March 5 Share Posted March 5 It is my general observation that around 1931 the pot metal was made different and seems to last much better. Most of the earlier pot metal turned into what I would call baked clay over time. 3 Link to comment Share on other sites More sharing options...
kramaton Posted March 5 Share Posted March 5 I would say pot metal was an economical metal. I don't think any company making cars was looking ahead 100 years. 5 1 Link to comment Share on other sites More sharing options...
Larry Schramm Posted March 5 Share Posted March 5 (edited) Economical may have been one factor for pot metal/ diecast, but really it was used because it could be injected into molds for many complex types of parts easily and economically. Besides door handles, distributor housings, also speedometer frames and many more types of applications. Just think of diecast as the plastic of the time, prewar manufacturing process. Edited March 5 by Larry Schramm (see edit history) 12 Link to comment Share on other sites More sharing options...
Fordy Posted March 5 Share Posted March 5 Does anyone know the make-up of it? I am thinking an Aluminum +zinc mix and more? There once was an old guy in Australia who could weld broken bits of "Die cast" back together but he is long gone. Steve Link to comment Share on other sites More sharing options...
JRA Posted March 5 Share Posted March 5 Pot metal is a nightmare for 1920s car collectors!!! My experience is depending on the car manufacturer, you get different quality material. Some are broken and weak over time, others have good resistance. Maybe, I think probably every manufacturer used a different component/concentration mix for pot metal. 2 Link to comment Share on other sites More sharing options...
Larry Schramm Posted March 5 Share Posted March 5 Here is an article on metal printing that some of you might find interesting. https://www.techbriefs.com/component/content/article/50179-rapidly-printing-with-liquid-metal?utm_source=TB_Main_News&utm_medium=email&utm_campaign=20240305&oly_enc_id=4468A2030134E7X 1 Link to comment Share on other sites More sharing options...
DFeeney Posted March 5 Share Posted March 5 A person told me once "Early" pot metal was made the same way "Fig Newtons" are made today in bakeries. At the end of the day all the different left over dough is mixed together and made into Fig Newtons. By the early 30's they were looking more closely at the mixture. I have seen many early pieces of die cast in remarkable shape. I think it had something with the Zinc content used that particular day. 1 Link to comment Share on other sites More sharing options...
46 woodie Posted March 5 Share Posted March 5 The term "pot metal" came from shops that do castings and literally threw zinc, lead, aluminum, tin, magnesium, and even small amounts of iron shavings into the "pot" for castings. It was used as a way to use scrap's of waste metals and cutting costs. It has a low melting point and easily poured into molds and castings. Over time depending on humidity and other conditions it can be attacked by what is known as "zinc pest" and "white corrosion" causing it to literally fall apart under the right conditions. It is almost unrepairable with weld, braze or solder. I don't believe there is a metallurgic standard for pot metal. Link to comment Share on other sites More sharing options...
jp1gt Posted March 5 Share Posted March 5 I have had good luck with products that you mix sand like stuff and super glue, just coating the whole thing with it. Link to comment Share on other sites More sharing options...
carbking Posted March 5 Share Posted March 5 Wikipedia has a good short article on "pot metal". I had a metalurgist test for content on some of the early stuff used on Stromberg carburetors. He commented that the test material contained more than 3 times the lead as more modern (and stable) pot metal, and it was his belief that impurities in the lead caused much of our grief as far as cracking, etc. Stromberg seems to have changed the mixture around 1931~1932, with the later material being much more durable. Different companies solved the issue (or not) at different times. Jon 4 3 Link to comment Share on other sites More sharing options...
ron hausmann Posted March 6 Share Posted March 6 (edited) All, I’ve had good results in patching cracked pot metal parts with J B Weld. Stewart tank bottoms, tank tops, crankcase front covers, etc. as long as the parts still fit and aren’t t warped, and as long as the parts aren’t stress carrying, that seems to last successfully. On parts like pot metal generator endlayes, handles, etc. don’t bother. I just have those pieces machined out of brass or recast. Remy generators in the twenties used crappy pot metal on many of their units, which makes replacement a big problem. After so many decades, those end plates crack and pot metal actually curls and warps, making them useless as patterns. Brass replacements or aluminum need to be made. Ron Hausmann P.E. Edited March 6 by ron hausmann (see edit history) 3 1 Link to comment Share on other sites More sharing options...
30DodgePanel Posted March 6 Share Posted March 6 (edited) 20 hours ago, carbking said: I had a metalurgist test for content on some of the early stuff used on Stromberg carburetors. He commented that the test material contained more than 3 times the lead as more modern (and stable) pot metal, and it was his belief that impurities in the lead caused much of our grief Sounds like a lot of the scraps must have been collected at the end of each shift and sent to a melting location. Could those impurities have also included oils, dirt and greases that might of been used in the machining process and from anything that made contact with the floor? I can see why it failed so miserably .... Edited March 6 by 30DodgePanel (see edit history) Link to comment Share on other sites More sharing options...
46 woodie Posted March 6 Share Posted March 6 I don't think the oil and grease would be a factor, as they would burn up during the melting cycle and impurities such as dross and slag are skimmed off before pouring into molds. 1 1 Link to comment Share on other sites More sharing options...
arcticbuicks Posted March 6 Share Posted March 6 I wonder if panned obsolescence .....started earlier than i thought ? Link to comment Share on other sites More sharing options...
theconvertibleguy Posted March 7 Share Posted March 7 There was a '47 Monarch that I was looking at where a few of the parts were made of pot metal, and wore out accordingly. Link to comment Share on other sites More sharing options...
mechanician Posted March 7 Share Posted March 7 On 3/5/2024 at 11:14 AM, DFeeney said: A person told me once "Early" pot metal was made the same way "Fig Newtons" are made today in bakeries. At the end of the day all the different left over dough is mixed together and made into Fig Newtons. By the early 30's they were looking more closely at the mixture. I have seen many early pieces of die cast in remarkable shape. I think it had something with the Zinc content used that particular day. I think that comparison is an insult to fig Newtons! 4 Link to comment Share on other sites More sharing options...
Ozstatman Posted March 7 Share Posted March 7 This reminds me of Ed's "floor sweepings'. 2 Link to comment Share on other sites More sharing options...
Rusty_OToole Posted March 7 Share Posted March 7 Reminds me of an analysis I heard of, concerning the cast aluminum door hinges used on VW Karmann Ghias. The guy who was trying to reproduce the hinges said "wow that is the most complicated alloy I have ever seen" a metallurgist friend laughed and said "that is what you get when you throw all the scrap you can find into the pot along with some floor sweepings and a few old turnips". Then there was a prewar German racing car, I think an Auto Union, that needed a new cylinder head. A British firm set out to reproduce it with the help of the Reynolds Aluminum company. Their metallurgist analyzed the head and remarked "this is the kind of stuff we use for lawn furniture and lamp posts". But it was the best aluminum alloy available in 1937. 2 Link to comment Share on other sites More sharing options...
yachtflame Posted March 7 Share Posted March 7 23 hours ago, 30DodgePanel said: Sounds like a lot of the scraps must have been collected at the end of each shift and sent to a melting location. Could those impurities have also included oils, dirt and greases that might have been used in the machining process and from anything that made contact with the floor? I can see why it failed so miserably .... But when you think about it, a lot of these parts are close to 100 years old. How many parts on a new car do you think will be around and in good condition 100 years from now? 3 Link to comment Share on other sites More sharing options...
46 woodie Posted March 7 Share Posted March 7 Most car makers today will admit that most of the plastic parts in cars today will most likely fail in 10 to 12 years. Sunlight, heat and cold weather are the biggest cause of plastic failure. 1 Link to comment Share on other sites More sharing options...
Rusty_OToole Posted March 7 Share Posted March 7 4 hours ago, 46 woodie said: Most car makers today will admit that most of the plastic parts in cars today will most likely fail in 10 to 12 years. Sunlight, heat and cold weather are the biggest cause of plastic failure. I have seen it. My 20 year old Chev Impala's mirror clipped a new Honda's mirror. The Honda mirror bounced back without a scratch, my mirror broke off. I suspect when my car was new the plastic would have been much more flexible. Many GM cars from the 80s have bumper fillers that have cracked and crumbled to bits. This is a common problem. 1 Link to comment Share on other sites More sharing options...
Studebuddy Posted March 7 Share Posted March 7 On 3/5/2024 at 1:34 AM, JRA said: Pot metal is a nightmare for 1920s car collectors!!! My experience is depending on the car manufacturer, you get different quality material. Some are broken and weak over time, others have good resistance. Maybe, I think probably every manufacturer used a different component/concentration mix for pot metal. Yes, PITA for 20's cars. Our Studebaker's had pot metal ignition switch headlight levers they swell and break over time. Also had pot metal upper distributor housing where the cap sits... those also swell and crack. So you can ask me what parts on my car are not original, but I'll bet you can guess... 1 Link to comment Share on other sites More sharing options...
jukejunkie1015 Posted March 8 Share Posted March 8 Pot metal was not only an automotive problem. Any mechanical items that were mass-produced from the mid-1920s to the early 1930s contained pot metal and failure is expected. I run across it radios, clocks, piano actions, statuary, phonographs (especially reproducers), electrical switches and knobs, and elbows and nipples for vacuum lines. Swelling and cracking are obvious but often while looking good it will disintegrate with any usage. When I was young ( in my mid-60s now) the oldtimers always said the fresh batch of metal they made on Monday made a good product but by the end of the week after constantly being reheated with the sprues and leftover metal being tossed in, you were lucky to get a year. I hate the stuff but it seems to be part of all my restoration projects. 2 Link to comment Share on other sites More sharing options...
31 LaSalle Posted March 8 Share Posted March 8 Pot Metal a difficult metal to have rechromed 1 Link to comment Share on other sites More sharing options...
28 Chrysler Posted March 8 Share Posted March 8 I have a Stromberg OE1 carb that still has no sign of cracking or swelling and is completely functional at 97 years old. The rest of the pot-metal on the car is junk, trash or broken 1 Link to comment Share on other sites More sharing options...
carbking Posted March 8 Share Posted March 8 Most Stromberg OE-1 carbs were brass; a few were aluminum. I am not aware of one that is zinc alloy. Jon Link to comment Share on other sites More sharing options...
28 Chrysler Posted March 12 Share Posted March 12 On 3/8/2024 at 3:33 PM, carbking said: Most Stromberg OE-1 carbs were brass; a few were aluminum. I am not aware of one that is zinc alloy. Jon Thanks for the info. Link to comment Share on other sites More sharing options...
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