Recently, I was asked about the interchangeability of vaporizers between old U.S. Military single-burner stoves. Typically, I try to keep the original vaporizers with the stove as a matter of practice, however, as time goes on and old vaporizers become unusable the need arises to find suitable replacements.
Physically, the vaporizers for the Coleman 520/AGM M1941, M1942 and M1950 are all very similar, so I will compare these three stoves. There are three things to focus on; vaporizer threads which allows the burner bowl to attach, the tip-cleaner needle, and the beveled mating surface.
This post edited 27 November 2016 to add information about M1942 internal part differences.
One question asked concerns the vaporizer threads. All three vaporizers use the same thread pitch and diameter. Therefore, all three vaporizers will thread into any of the three burner bowls. I tried this myself, using a 1944 Coleman 520, a 1945 Pretiss Wabers M1942 and a 1966 Rogers M1950 stove. Overall length of any of the three vaporizers/burner bowl combinations, when installed in an M1942 burner bowl was 55mm. I have noticed that some vaporizers do not thread into the burner bowl as completely as others. I think this is a manufacturing tolerance issue. The thread is a pipe thread, and therefore tapered. The only time I’ve found this to be a problem is on the M1950 stove where I’d like the burner bowl to be flush with the top of the windscreen. Sometimes it extends above the windscreen and this isn’t right.
The tip cleaners themselves are different in several ways. First, there is the threaded type which are used in the 520/M1941 and the M1942. The 520/M1941 uses the locking nut, while the M1942 does not. I gathered tip cleaners (8 of them) from both stove models and they all threaded into the M1942 valve assembly. Second, the M1950 tip cleaner omits the threads and instead has a hook on the end. Third, I noticed was that some tip cleaners did not pass through the vaporizer tip, as if the cleaning wire was slightly thicker on some versions. Also, some tip cleaners have a taper on the rod of the wire end and I’m not certain if this plays a factor or not. One final note is that all of my M1942 vaporizers (about 10) have a hex-head vaporizer tip while most 520/M1941 and all M1952 vaporizers have only two flat sides. My 1943 Coleman 520 came with the hex tip, however, so I cannot say this is a rule. Who knows what got swapped out over the years or even when used in the service?
27NOV2016 -Something I learned recently, while assembling a 1944, M1942 Aladdin stove, was that the stainless steel disk which mates the vaporizer to the valve body is different (see photo in next section) than the Prentiss Wabers. I assembled the stove with the vaporizer and tip cleaner that came with the stove when I bought it. When I assembled everything I could not get a good stream of fuel, and when I lit the stove it sputtered and went out repeatedly. I checked to ensure that the tip cleaner was retracted, but it just wouldn’t work properly. The Prentiss Wabers SS disk is taller on the side which mates to the vaporizer which means it has more room and can accept a taller tip cleaner. I swapped out the tip cleaner with a different tip cleaner with a shorter wire, reassembled the stove and it worked flawlessly. It appears that if I used one with a longer wire, it didn’t completely clear the vaporizer’s tip and restricted fuel flow.
Beveled Mating Surface
Given the above information it would seem likely that any of the vaporizers will work in any of the stoves, if the correct tip cleaner is used, but hold on. The M1942 has a stainless steel disk with a square shoulder where the vaporizers seals, while the other two stoves have a beveled mating surface of approximately 46 degrees on the valve body. Side Note – The valve body at the base of the beveled surface is 11mm on both the 520/M1941 and M1950 and the thread pitch is the same, so you can swap pre-heat cups (spirit cups) between these two stoves. I tried this out and since I am missing the pre-heat cup/nut on an M1950, I plan to use one from a 520 until I locate the correct part for a decent price.
What I found was that most 520/M1941 vaporizers that I have and some older M1950 vaporizers will fit on the M1942 while some do not. Since the inside beveled surface must seal to the square shoulder, the vaporizer must have a small gap (see photos) to seal properly. Some of my 520/M1941 vaporizers and my older M1950 vaporizers have this gap, so they should seal properly. In fact, some old M1942 vaporizers will no longer seal properly because the stainless steel disk wears a groove in the vaporizer, so removing and reinstalling it creates more wear. Once I get one of these installed and working properly, I don’t take them apart again unless absolutely necessary. You can check to see if this will work before assembly by holding the disk in one hand and placing the vaporizer on the disk with your other hand. If it rocks back and forth a little, it means that the shoulder is making contact properly with the vaporizer’s mating surface. There are some differences in M1942 internal parts between manufacturers, so keep reading.
My newer NOS (New Old Stock) M1950 vaporizer does not have this gap, as it sits flush to the stainless steel disk. Without even testing it in an actual M1942 Aladdin stove, I’m confident this will leak.
I am thinking that if I were to file or grind down the bottom of the M1950 NOS vaporizer to the point where the shoulder on the stainless steel disk meets the inside bevel it might be made to work (on an Aladdin stove). If you look carefully at the photos you’ll see that the flared end of the M1950 vaporizer has more brass there than the other two styles. I haven’t tried this and don’t have a spare one to experiment with at this point.
Update 27NOV2016 – The above is using Aladdin stove parts. Note that, as mentioned earlier, the Prentiss Wabers stainless steel disk is taller (see photo) and more likely to work properly with a wider range of vaporizers. I tried the same test as above with the M1950 NOS vaporizer and it has the necessary gap between the vaporizer base and the disk.
Some vaporizers available in an M2 spare parts tube might work. I have one of these and the vaporizer appears to have just a little rocking motion so it may seal, but I haven’t tried it.
Summary of Interchangeability
In summary (Updated 27NOV2016),
- M1942 vaporizers appear to also fit 520/M1941 and M1950 stoves, though the appropriate tip cleaner needs to be used and some tip cleaning wires may be too thick.
- 520/M1941 vaporizers may, or may not, fit the M1942 stove (and, more likely to fit the Prentiss Wabers than the Aladdin). Not sure about the Coleman), so check carefully. They should fit the M1950 with the correct tip cleaner and verify that the tip cleaning wire fits and isn’t too long.
- M1950 vaporizers will fit the 520/M1941 stove but the correct tip cleaner (threaded) must be used. And some, especially the older ones, appear to fit the M1942 stove but you must examine carefully and test for fuel leaks before firing the stove and then again after lighting it up, assuming it sealed when cold. Newer M1950 vaporizers like the one in the photo do not fit properly on the M1942 Aladdin stove, but it did fit on my Prentiss Wabers stove.
Since this isn’t as straight-forward as one would think, it is easy to see cause for confusion. If you have questions feel free to contact me. As with all of these old stoves, test and retest before putting a match to the gas, and light it up outdoors until you’re confident it is working safely. Be sure to check out my other blog posts on all three of these stoves.
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